Biosensors 2016 - Hacettepe International... · · 2016-10-18Abstract Book ... 5-7 October 2016...

Abstract Book

www.biosensor2016.hacettepe.edu.tr

5-7 October 2016 Ankara, Turkey

Biosensors 2016

3rd International Congress on Biosensors Biomaterials, Bioinformatics, Biosensors, Electrochemistry, Nanobiotechnology, Nanomaterials, Single-cell detection & analysis, Natural & synthetic receptors, MicroPADs, Microfluidic systems and more….

Hacettepe University, Mehmet Akif Ersoy Hall, Beytepe Campus

Organized by

Hacettepe University Gazi University Bilkent University

Dear Colleagues,

It was a great pleasure for us to see you in the 3rd International Congress on Biosensors. The

congress was organized by Hacettepe University with the jointly contribution of Bilkent and

Gazi Universities.

Located at the capital of Turkey, the congress attracted top scientists, decision and policy

makers, high-tech companies, start-up companies, entrepreneurs, investors and students from

all around the region.

This three day Conference provided access to the most up-to-date and authoritative

knowledge from both commercial and academic worlds, sharing best practice in the field as

well as learning about case studies of successfully integrated bio-sensing technologies. The

meeting provided the opportunity to highlight recent developments and helped many to

identify the emerging and future areas of growth in this exciting field.

We are so happy to have you welcomed to Ankara for 3rd International Congress on

Biosensors.

Sincerely yours,

Assoc. Prof. Dr. Memed Duman

3rd International

Congress on Biosensors

5-7 October 2016

Mehmet Akif Ersoy Hall

Honorary President

Prof. Dr. A. Haluk Özen, Hacettepe University

Congress Chair

Assoc. Prof. Dr. Memed Duman, Hacettepe University

Congress Co-Chair

Assoc. Prof. Dr. Çağlar Elbüken, Bilkent University

Assoc. Prof. Dr. Gökhan Demirel, Gazi University

Organizing Committee

Gülgün Aylaz, Hacettepe University

Esma Sari, Hacettepe University

Meltem Okan, Hacettepe University

Selim Sülek, Hacettepe University

İpek Akyılmaz, Hacettepe University

Congress Topics

Bioinformatics

Biomaterials

Commercial biosensors, manufacturing and markets

Electrochemistry

Microfluidics/Lab-on-a-chip devices

Molecular biology

Nanobiotechnology

Nanomaterials and nanoanalytical systems

Natural and synthetic receptors

Next generation sequencing microRNA

Organism- and whole cell-based biosensors

Aptamer based biosensors

DNA microarray chips and sensors

Enzyme biosensors

Immunosensors

Neurosensor

Optical sensors

MicroPADs

Printed biosensors and organic electronics

Sensors to Monitor Food Quality and Safety

Single-cell detection and analysis

WEDNESDAY, OCTOBER 5, 2016, 3rd INTERNATIONAL CONGRESS ON BIOSENSORS

08:30-09:30 Registration

09:30-09:45 Opening Talk Memed Duman (Congress Chair), Hacettepe University Prof. Dr. A. Haluk Özen (Rector-Honorary President), Hacettepe University

Session Chair: Dirk Mayer

09:45-10:30 Plenary Speaker- Arben Merkoçi, Catalan Institute of Nanoscience and Nanotechnology PS0101-“Nanomaterials-based sensors for diagnostics applications”

10:30-11:00 Invited Speaker- Vural Gökmen, Hacettepe University IS0101-“Machine Vision-Tool to Monitor Food Quality and Safety During Processing”

11:00-11:15 Coffee Break

Session Chair: Arben Merkoçi

11:15-11:45 Invited Speaker- Suna Timur, Ege University IS0102-“Integration of Biomolecules to Electrochemical and Optical Systems”

11:45-12:15 Invited Speaker- Alper Kiraz, Koç University IS0103-“Optofluidic Microresonators for Bio/Chemical Sensing Applications”

12:15-12:30 Oral Presentation- Gökhan Bakan, Antalya International University OP0101-“Pattern-Free, CMOS Compatible Infrared-Absorption-Spectroscopy Surfaces for Sensing Bio-Molecule Monolayers”

12:30-12:45 Oral Presentation- Müslüm Kaan Arıcı, Middle East Technical University OP0102-“Salmonella Detection via Silica Nanoparticle based Lateral Flow Test Platform”

12:45-13:00 Oral Presentation- Nilgün Dükar, Ordu University OP0103-“miRNA Sensing Self-Propelled Hybrid Micromotors”

13:00-14:30 Lunch Break

Session Chair: Mustafa Kemal Sezgintürk

14:30-15:00 Invited Speaker- Canan Dağdeviren, Harvard University IS0104-“An ‘Unusual’ Story: The Biology Meets Its Match “

15:00-15:30 Invited Speaker- Filiz Kuralay, Ordu University IS0105-“Impact of Nanotechnology on Biomedical Sciences: Biosensing and Drug Delivery”

15:30-15:45 Oral Presentation- Murat Serhatlıoğlu, Bilkent University OP0104-“Fabrication and Characterization of Miniaturized Optical Flow Cytometry Design”

15:45-16:00 Oral Presentation- Zeynep Çağlayan, Middle East Technical University OP0105-“Dielectrophoretic Spectra of Polymorphonuclear White Blood Cells”


Session Chair: Suna Timur

16:15-16:45 Invited Speaker- Humphrey Yiu, Heriot Watt University IS0106-“Surface Functionalization of Nanoparticles for Immunosensing of Biomolecules”

16:45-17:00 Oral Presentation- Rükan Genç, Mersin University OP0106-“Synthesis of Functionalized Fluorescent Carbon Nanoparticles as Artificial Enzymes and Signaling Tools for Their Use in Bioanalysis”

17:00-17:15 Oral Presentation- Selmihan Şahin, Süleyman Demirel University OP0107-“Preparation of Polypyrrole based Electrodes for Glucose 6-Phosphate Determination”

17:15-19:00 Poster Presentations Session 1

PP0101-PP0156

THURSDAY, OCTOBER 6, 2016, 3rd INTERNATIONAL CONGRESS ON BIOSENSORS

Session Chair: Haluk Külah

09:00-09:30 Invited Speaker- Dirk Mayer, Forschungszentrum Jülich IS0201-“Aptamer-based Biosensor with Electrochemical Current Rectification as Signal Amplification Strategy”

09:30-10:00 Invited Speaker- Selim Ünlü, Boston University IS0202-“Multiplexed Digital Detection of Protein Biomarkers for Cancer Diagnosis”

10:00-10:15 Oral Presentation- Hilay Şencan, Boğaziçi University OP0201-“Investigation of Protein Adsorption on Gradually Reduced Graphene Oxide Modified Surfaces by QCM”

10:15-10:30 Oral Presentation- Erhan Zor, Necmettin Erbakan University OP0202-“Paper-based Sensors as Optical Chiral Discrimination Platform”


Session Chair: Selim Ünlü

11:00-11:30 Invited Speaker- Haluk Külah, Middle East Technical University IS0203-“BioMEMS and Microfluidic Devices for Lab-on-a-Chip Applications”

11:30-12:00 Invited Speaker- Mustafa Kemal Sezgintürk, Namık Kemal University IS0204-“ITO based Disposable Biosensors and New Immobilization Agents”

12:00-12:15 Oral Presentation- Ziya Işıksaçan, Bilkent University OP0204-“Point-of-Care Measurement of Erythrocyte Sedimentation Rate”

12:15-12:30 Oral Presentation- Fatma Doğan, Eskişehir Osmangazi University OP0205-“Nanopore-Integrated Microfluidic Biosensors with Single Molecule Detection Capability”

12:30-13:00 Oral Presentation- Yeliz Yavuz Çelik S0201- “Metrohm Autolab and DropSens News”


Session Chair: Yıldız Uludağ

14:30-15:00 Invited Speaker- Uğur Tamer, Gazi University IS0205-“Rapid Detection Strategies for Pathogens Using Functionalized Nanoparticles”

15:00-15:15 Oral Presentation- Murat Uygun, Adnan Menderes University OP0206-“Biomimetic Carbon Dioxide Sequestration by Using Carbonic Anhydrase Attached Micromotors”

15:15-15:30 Oral Presentation- Mustafa Yorulmaz, ASELSAN Research Center OP0207-“Single-Particle Imaging for Biosensor Applications”

15:30-15:45 Oral Presentation- Kutay İçöz, Abdullah Gül University OP0208-“Cell Phone Microscopy + Image Processing: Low Cost Readout Method for BioMEMS”

15:45-16:00 Oral Presentation- Sevde Altuntaş, TOBB Economics and Technology University OP0209-“Detection of Alzheimer`s Protein on Polycarbonate Nanopillared Films by Using Surface Enhanced Raman Spectroscopy”


Session Chair: Alper Kiraz

16:15-16:45 Invited Speaker- Yıldız Uludağ, TÜBİTAK BİLGEM IS0206- “MiSens Device as a New Automated Biosensing Platform based on Real-time Electrochemical Profiling (REP)”

16:45-17:00 Oral Presentation- Eda Çelik, Hacettepe University OP0210-“Glycophage based Array as an Alternative Biosensor for Pathogen Detection”

17:00-17:15 Oral Presentation- Resul Sarıtaş, Siirt University OP0211-“Detection of Micro and Nanoparticles in a Microfluidic Device Using Resistive Pulse Sensing Technique”

17:15-19:00 Poster Presentations Session 2 PP0201-PP0256

19:30 Gala Dinner

FRIDAY, OCTOBER 7, 2016, 3rd INTERNATIONAL CONGRESS ON BIOSENSORS

Session Chair: Filiz Kuralay

09:00-9:30 Invited Speaker- Urartu Özgür Şafak Şeker, Bilkent University

IS0301- “Synthetic Genetic Circuits Operated Whole Cell Biosensors”

09:30-10:00 Invited Speaker- Adil Denizli, Hacettepe University

10:00-10:15 Oral Presentation- Fatih Şen, Dumlupınar University OP0301-“Next Generation Biosensors: Near-Infrared Fluorescent Single-Walled Carbon Nanotubes”

10:15-10:30 Oral Presentation- Meltem Okan, Hacettepe University OP0302-“Molecularly Imprinted Polymer based Microcantilever Sensor for the Selective Determination of Erythromycin in Water Resources”


Session Chair: Urartu Özgür Şafak Şeker

10:45-11:15 Invited Speaker- Ömür Çelikbıçak, Hacettepe University IS0303-“Mass Spectrometry in Biomedical Research”

11:15-11:30 Oral Presentation- Hasret Subak, Yüzüncü Yıl University OP0303-“Electrochemical Detection of Interaction Between Plantago Anatolica and DNA by Using Disposable Biosensors”

11:30-11:45 Oral Presentation- Mehmet Yılmaz, Sinop University OP0304-“ Thin Films of p-type Organic Semiconductors as SERS Substrates”

11:45-12:00 Oral Presentation- Gözde Aydoğdu Tığ, Ankara University OP0305-“Simultaneous Electrochemical Determination of Ascorbic acid, Dopamine and Uric Acid based on Gold Nanoparticles-Graphene oxide-Poly-(2,6-Pyridinedicarboxlic Acid) Modified Electrode”

12:00-12:15 Oral Presentation- Irmak Karaduman, Gazi University OP0306-“Acetone Gas Sensor based on ZnO Nanostructure Produced by Successive Ionic Layer Adsorption and Reaction (SILAR) Method”

12:15-12:30 Oral Presentation- Pınar Kara, Ege University OP0307-“Biosensing Strategy for Detection of Bacterial Susceptibility Against Beta Lactamases”

12:30-12:45 Oral Presentation- Dilber Ece Sezgin, Eskişehir Osmangazi University OP0308-“RNA SELEX for Green Fluorescent Protein and Application of Selected Aptamer to Optic Biosensors”


Session Chair: Ömür Çelikbıçak

14:30-15:00 Invited Speaker- Arzum Erdem Gürsan, Ege University IS0304-“Nanomaterials Integrated Electrochemical Biosensors”

15:00-15:15 Oral Presentation- Günnur Güler- Ege University OP0309-''Rapid Detection of Disease Biomarkers with ATR-FTIR Spectroscopy''

15:15-15:30 Oral Presentation- Derya Koyuncu Zeybek, Dumlupınar University OP0310-“A Label-Free Electrochemical Immunosensor based on ERGO for Determination of Hemoglobin A1c”

15:30-15:45 Oral Presentation- Gülgün Aylaz, Hacettepe University OP0311-“A Novel Fiber based MALDI Probe for Selective Detection of Ciprofloxacin”

15:45-16:00 Oral Presentation- Zeeshan Rashid, Koç University OP0312-“Smart Surface based Guiding of Microdroplets Over Laser Ablated Sinusoidal Rail”

16:00-16:15 Oral Presentation- Recep Üzek, Hacettepe University OP0313-“ Functional GQDs Nanocomposite Fabricated for Direct and Rapid Detection of BPA with Paper Based Fluorescent System”

16:15-17:15 Closing and Award Ceremony

ABSTRACTS

Invited

Speakers

3rd International Congress on Biosensors, 5-7 October 2016, Ankara

Nanomaterials-based sensors for diagnosticsapplications

Arben Merkoçi1

1 CREA Research Professor & Group Leader Nanobioelectronics & Biosensors Group Catalan Institute of Nanoscience

and Nanotechnology (ICN2) Campus de la UAB 08193 Bellaterra (Barcelona) Spain& CIN2 (ICN-CSIC) Barcelona,

Catalonia, Spain

Machine Vision-Tool to Monitor Food Quality and Safety During Processing

Vural Gökmen1

1Food Engineering Department, Hacettepe University, Ankara, Turkey

Integration of Biomolecules to Electrochemical and Optical Systems

Suna Timur1

1Ege Üniversitesi, Fen Fakültesi, Biyokimya Bölümü, Bornova, İzmir, Turkey

Surface Functionalization of Nanoparticles for Immunosensing of Biomolecules

Humphrey Yiu1

1School of Engineering & Physical Sciences; Mechanical Process & Energy Engineering, Heriot-Watt University,

Edinburgh, Scotland, UK

Aptamer-based Biosensor with Electrochemical Current Rectification as Signal

Amplification Strategy

Dirk Mayer1

1Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich, Jülich, Germany

MiSens Device as a New Automated Biosensing Platform based on Real-time

Electrochemical Profiling (REP)

Yıldız Uludağ1

1TÜBİTAK BİLGEM

Synthetic Genetic Circuits Operated Whole Cell Biosensors

Urartu Özgür Şafak Şeker1

1UNAM National Nanotechnology Research Center, Bilkent University, Ankara, Turkey

http://unam.bilkent.edu.tr/


Optofluidic Microresonators for Bio/Chemical Sensing Applications

Alper Kiraz1*

Departments of Physics and Electrical-Electronics Engineering

1Koç University, Rumelifeneri Yolu, 34450 Sariyer, Istanbul, Turkey

[email protected]

Abstract

Fluids possess unique properties for designing optical

components and systems: (i) they have optically smooth

interfaces and (ii) they provide a great flexibility in shape and refractive index. Optofluidics has recently

emerged as an exciting new research field employing

these unique properties of fluids to design optical

components and systems that cannot be realized with

classical solid-state materials. Optofluidic platforms

usually exploit established design and manufacturing

principles developed within the past two decades for the

production of microfluidic chips. In this presentation, I

will present some alternative approaches we have

followed in my research group which can serve as

inspirations for future optofluidic platforms.

Microdroplets of water and other polar liquids take

almost spherical shapes when standing on a

superhydrophobic surface. With their truncated

microsphere geometry, they act as optical microcavities

hosting whispering gallery modes. I will summarize the

novel spectral tuning techniques, and organic/bio

emitting device concepts, we developed using

microdroplets that are standing on a superhydrophobic surface or trapped using different manipulation

methods. I will discuss the recent experiments we have

performed on optical spectroscopy of microdroplets

using tapered optical fibers.

I will also discuss our results on hydrogen and humidity

sensing using microdisk structures fabricated by SU-8

photoresist. The results that I will describe were partially supported by TÜBİTAK Grants No: 110T803,

112T972, and 115F446.


Nanomaterials Integrated Electrochemical Biosensors

Arzum Erdem1

1Ege University, Faculty of Pharmacy, Analytical Chemistry Department, 35100 Bornova, Izmir, Turkey

[email protected]

[email protected]

Abstract

The nanoscale materials integrated sensors based on

nanoparticles, nanowires, dendrimers, nanotubes and other nanomaterials have recently received the

considerable attention [1-6]. The development of

advanced biosensor platforms could impact

significantly the areas of genomics, proteomics,

biomedical diagnostics and drug discovery.

Electrochemical biosensors coupling the inherent

specifity of biorecognition reactions with high

sensitivity of physical transducers, present a great

promise for sequence-specific nucleic acid

detection (DNA, RNA etc.) for clinical,

environmental or forensic investigations [1-6].

An overview to nanomaterials integrated

electrochemical biosensors has been presented

herein for monitoring of spesific biomolecular

recognitions; such as, nucleic acid hybridization,

aptamer-protein or drug-DNA interactions with

their advantages and further applications.

References

1. Palecek E., Bartosik M., (2012) Chem. Rev.,

112; 3427.

2. Gao W., Wang J., (2014) Nanoscale, 6; 10486.

3. Patolsky F., Lieber C.M., (2004) Materials

Today, 8; 20.

4. Sassolas A. , Leca-Bouvier B.D., Blum L.J.,

(2008) Chem. Rev., 108; 109.

5. Ma W., Situ B., Lv, W. et al., (2016) Biosens

Bioelectron., 80; 344.

6. Erdem A., (2007) Talanta, 74; 318.

mailto:[email protected]



An ‘Unusual’ Story: The Biology Meets Its Match

Canan Dağdeviren1

1Koch Institute for Integrative Cancer Research, MIT, USA

Abstract

Multifunctional sensing capability, ‘unusual’ formats with flexible/stretchable designs, lightweight

construction and self-powered operation are desired

attributes for electronics that directly interface with the

human body. Today’s electronics are stiffer by up to six

orders of magnitude compared to soft tissue. Thus,

present systems limit intimate integration with biology.

I have focused on novel microfabrication techniques

and tricks to use active piezoelectric materials and

required electronic components, which have the shape

and the mechanical properties that match with those of

human tissues, in order to allow intimate integration without any irritation and/or harm on body.

In this talk, I describe novel materials, mechanics and

device designs for emerging classes of wearable health

monitoring systems and implantable, minimally

invasive medical devices. These include a variety of

electrodes, sensors, and energy harvesting components,

with promising applications in bio-integrated electronics, such as self-powered cardiac pacemakers,

wearable blood pressure sensors, modulus sensor

patches, and brain injectrodes. The devices can be

twisted, folded, stretched/flexed and wrapped onto

curvilinear surfaces or implanted without damage or

significant alteration in operation. The fabrication

strategies and design concepts can be applied to various

biological substrates and geometries of interest, and thus

have the potential to broadly bridge the gap that exists

between rigid, boxy electronics and soft, curvy biology.


Impact of Nanotechnology on Biomedical Sciences: Biosensing and Drug

Delivery

Filiz Kuralay1

1Faculty of Art and Sciences, Ordu University, Ordu, Turkey

Abstract

Nanoscale materials have drawn great attention in

recent decades for the development of new

technologies. These materials including carbon

nanotubes, graphene, nanoparticles, nanowires and

nanostructured polymers are widely used in

biomedical, pharmaceutical, forensic, food safety,

energy storage and environmental applications due

to their excellent chemical, mechanical, electrical,

structural, optical and thermal properties. They

constitute an emerging, interdisciplinary field of

science for developing new detection methods and

scientific investigations of the materials obtained.

Nanomaterials-based methods have various

commercial and technological applications with the

advantage of eliminating the use of laborious,

expensive and complex methods. The aim of this

talk will be focusing on various nanomaterials-

based studies developed for the detection of nucleic

acids and neurotransmitters and nano/

microactuators for controlled drug release and

delivery.

http://fenedebiyat.odu.edu.tr/


BioMEMS and Microfluidic Devices for Lab-on-a-Chip Applications

Haluk Külah1,2

1METU MEMS Center, Ankara, Turkey

2METU, Electrical and Electronics Engineering Department, Ankara, Turkey

Abstract

This presentation introduces MEMS and microfluidics technology for biomedical applications, including their applications with examples from the literature. BioMEMS related projects at METU-MEMS Center will be presented. Since the first introduction in 1970’s, MEMS technology is becoming popular in many different application areas,

including military, automotive, and consumer electronics, as it provides cheap, small, and smart sensors and actuators. This technology is especially critical for biomedical applications, resulting in a new research area shortly called BioMEMS. BioMEMS can be defined in general as “devices or systems constructed using techniques inspired from microfabrication that are used for processing, delivery, manipulation, analysis, or construction of biological and chemical entities [1].”

Application areas of BioMEMS range from diagnostics to micro-fluidics, systems for drug delivery, tissue engineering, and implantable biomedical systems. One of the most interesting application areas for this technology is the micro total analysis systems (Micro-TAS). Biological samples can be analyzed in a very small area with considerably reduced cost and time, by forming micro-fluidic channels on silicon substrate and combining them with onchip electronics. Some

examples for such applications include on-chip electrophoresis systems, polymerized-chainreaction (PCR) units, DNA sequencing chips, and complex lab-on-a-chip devices [2-6]. These kinds of systems can be incorporated with wireless electronics technology and can be implanted inside the body for real time measurement of blood chemical values. Even further, it is possible to form small reservoirs on the same chip

for storing drugs and releasing them to the body according to the analysis results. Similar systems can be used for diagnosis purpose. In this case, the technology is used to detect predefined sort of cells, viruses, bacteria, proteins, or enzymes in blood or in another liquid environment. This application is very critical for prevention of diseases as well as early detection of them. Another interesting application for BioMEMS is smart bio-implants. Combining this technology

with complex CMOS circuitry, it is possible to produce biocompatible, small, smart and esthetic implants. There are currently various BioMEMS related projects going on at METU-MEMS, including DNA electrophoresis systems [3], dielectrophoresis chips for cell seperation [4], gravimetric sensors for cancer cell detection, microvalves and pumps for lab-on-a-chip systems [5], and electrochemical sensors for bacteria and toxin detection. Figure 1-3 show pictures of some prototypes developed in our group.

Figure 1 Micro-channels and valves developed at METU-MEMS Figure 2 DEP-based cell separation chips

Figure 3 Microfluidic bacteria detection system and droplet-based drug effect analysis chips.

Figure 4 Parylene-based neural probes developed at METU-MEMS

References

[1] R. Bashir, “BioMEMS: state-of-the-art in detection, opportunities and

prospects,” Advanced Drug Delivery Rev., Vol: 56, 11, 1565-86, 2004.

[2] V.M. Ugaz et. al. “Microfabricated electrophoresis systems for DNA

sequencing and genotyping applications: current technology and future

directions,” Philos Transact A Math Phys Eng Sci.; 362: 1105-1129,

2004.

[3] S. Sukas et. al., "A parylene based double-channel

microelectrophoresis

system for rapid mutation detection via heteroduplex analysis,"

Electrophoresis J., Vol. 29, No. 18, pp. 3752-58, 2008.

[4] G. Yılmaz et. al. "A Dielectrophoretic Cell/Particle Separator

Fabricated By Spiral Channels and Concentric Gold Electrodes,”

TRANSDUCERS'07, pp. 73-76, June 2009.

[5] E. Yıldırım et. al." An Electrostatic Parylene Microvalve for

Controlling In-Plane Flow,” μTAS 2009, October 2009.

[6] A.C.R. Grayson et. al., “A BioMEMS review: MEMS technology for

physiologically integrated devices,” Proceedings of the IEEE, Volume 92,

Issue 1, pp. 6 – 21, Jan. 2004.


ITO based Disposable Biosensors and New Immobilization Agents

Mustafa Kemal Sezgintürk1

1Namık Kemal University, Faculty of Arts and Science, Chemistry Department,

Biochemistry Division, Tekirdağ, Turkey

[email protected]

1. Introduction

The development biosensors has attracted a great

deal of interest due to their high sensitivity and

selectivity, and they are being increasingly used in

many fields, such as analytical chemistry, industrial

process monitoring and control, clinical

diagnostics, environmental monitoring and security,

and food safety. Biosensors are also attractive for

pharmaceutical and biomedical analysis due to their

sensitivity (ng/mL or less) and high selectivity, and

sometimes their specificity, high benefit/cost ratio, simple use and rapidity of data collection [1].

The major advantages of biosensors over

traditional analytical methods, which will certainly

lead in the near future to their even more

pronounced use in the biomedical field, are: the fact

that analyte detection can very often be made

without prior separation; the short response times

that make possible the real-time monitoring of

biological and manufacturing processes; their ease

of use, allowing in-field or point-of-care measurements; the flexibility and simplicity of

preparation; the possibility of mass production and

low production costs; and the possibility of

miniaturization and automatization. [2].

As for the electrochemical transducer, important

advances have been recently made thanks to the

introduction of new platforms for biosensor design,

such as nanotechnological materials and

nanostructured architectures (i.e., nanoparticles,

carbon nanotubes and nanofibres, graphenes,

nanostructured surfaces, etc.), which have improved the sensitivity of the assembly [3].

2. Results and Discussion

Materials used for the electrode and supporting

substrate are usually conductive materials

exhibiting low currents in an electrolyte solution,

free of any electroactive species, over a relatively

wide potential window.

Among the most frequently used materials for the electrode and supporting substrate is indium tin

oxide, ITO) based materials. Recently the

applications of indium tin oxide(ITO) film elec

trodes have increased interest in biosensor

fabrications owing to their high electrical

conductivities, excellent substrate affinity, wide

range electrochemical working area, stable

electrochemical and physical properties and also

very low costs although i thas disposable properties.

In this study, different biosensor systems based on

ITO substrates are reviewed. In these biosensing

devices, new immobilization agents are used

successively. Especially cancer biomarkers are

prefered as the targets of these newly developed

biosensor systems.

Acknowledgement: This study was supported by

The Scientific and Technological Research Council

of Turkey (TUBİTAK) by the project number of

113 Z 678.

References

[1] Cristea C, Hârceagă V, Săndulescu R.

Electrochemical sensor and biosensors. In:

Moretto LM, Kalcher K, editors. Environmental

Analysis by Electrochemical Sensors and

Biosensors. Vol. 1 Fundamentals. 1st ed. New

York: Springer; 2014. p. 155-165.

[2] Morrison DWG, Dokmeci MR, Demirci U,

Khademhosseini A. Clinical applications of micro- and nanoscale biosensors. In: Gonsalves

KE, Halberstadt CR, Laurencin CT, 22

Biosensors - Micro and Nanoscale Applications

Nair LS, editors. Biomedical Nanostructures.

1st ed. New York: John Wiley & Sons Inc.;

2008. p. 1-10.

[3] Farré M, Kantiani L, Pérez S, Barceló D. (

2009) Sensors and biosensors in support of EU

di‐ rectives. TrAC Trends Anal. Chem.

28(2):170-185.

http://www.intechopen.com/books/biosensors-micro-and-nanoscale-applications/new-materials-for-the-construction-of-electrochemical-biosensors#B1




Mass Spectrometry Applications in Biomedical Research

Ö. Çelikbıçak1

1Department of Chemistry, Hacettepe University, Ankara

[email protected]

Abstract

Mass spectrometry's characteristics including

unequaled sensitivity and detection limits have

raised it to an outstanding position among the other

analytical methods for diverse applications such as;

atomic physics, reaction physics, reaction kinetics,

geochronology, all forms of chemical analysis (especially in biomedicine and ion-molecule

reactions) and determination of thermodynamic

parameters [1]. By the early 1980s, mass

spectrometry was a well-established laboratory

technique for the characterization of small organic

molecules. But larger molecules - particularly

biological ones, including proteins, DNA and

complex carbohydrates - were proving to be a

challenge. Because mass analysis relies on the

ionization and detection of species in the gas phase,

the key problem was transferring sufficient energy to these large molecules to send them into the gas

phase without destroying them [2]. Mass

spectrometry has progressed extremely rapidly

during the last three decades: production, separation

and detection of ions, data acquisition, data

reduction, etc. This has led to the development of

entirely new instruments and applications. Today,

intact analysis of the high molecular weight

compounds (e.g. proteins, peptides,

oligonucleotides, carbohydrates, synthetic

polymers, large inorganic complexes etc.) are

possible using soft ionization mass spectrometry techniques having high precision and accuracy. The

most important soft ionization techniques of mass

spectrometry are Electrospray Ionization Mass

Spectrometry (ESI-MS) and Matrix Assisted Laser

Desorption/Ionization Mass Spectrometry

(MALDI-MS) which are well-suited for

macromolecular analysis. Additionally, complexes

of these macromolecules, formed by weak

noncovalent interactions, can be followed and

complex stabilities, stoichiometries and interaction

regions can be determined using the soft ionization mass spectrometry as well. More recently, after the

genome era, proteomics and metabolomics are

becoming more popular in the many fields of

biology and medicine. In those “omics” approach,

mass spectrometric techniques are not only useful

but also nearly essential [3]. Nowadays, advances

of mass spectrometry are serving the expectation of

comprehensive coverage for those studies that focus

on complex interactions within biological systems.

References

[1] Hoffmann, Edmond De., and Vincent

Stroobant. Mass Spectrometry: Principles and

Applications. Chichester, West Sussex,

England: J. Wiley, 2007. Print.

[2] Hansell, Claire. “Enter the Matrix.” Nat Meth

(2015). doi:10.1038/nmeth.3527. [3] Setou, Mitsutoshi, and Hisao Oka.

“Biomedical Mass Spectrometry.” Anal

Bioanal Chem (2011) 400: 1827.

doi:10.1007/s00216-011-4944-0


Multiplexed Digital Detection of Protein Biomarkers for Cancer Diagnosis

M. S. Ünlü1,2,3*, Fellow IEEE, F. Ekiz Kanik1, N. Lortlar Ünlü2,3, A. Usubütün4 and E. Ç. Seymour5

1 Electrical and Computer Engineering, Boston University, Boston, USA 2 Biomedical Engineering, Boston University, Boston, USA

3 Faculty of Medicine, Bahcesehir University, Istanbul, Turkey 4 Faculty of Medicine, Hacettepe University, Ankara, Turkey

5Aselsan, Ankara, Turkey

[email protected]

1.Introduction

Due to the lack of molecular analysis devices, clinical diagnosis relied mostly on medical history and physical

examination until about a hundred years ago. In modern medicine, in vitro tests are indispensable components of clinical practice with the sensitivity of standard immunoassays measuring protein biomarkers at picomolar concentrations. This level of sensitivity is sufficient for the diagnosis of infectious diseases when clear symptoms are present, however, it falls short for the detection of proteins that are important in cancer [1].

Perhaps one of the most exciting recent technological developments in biomarker analysis is single-molecule counting or digital detection, an approach that provides resolution and sensitivity beyond the reach of ensemble measurements [2-4]. Digital detection not only provides very high sensitivity, but also has the potential of making the most advanced disease diagnostic tools available at low cost. We have developed a single molecule detection

technology and we are exploring applications in highly sensitive diagnosis assays for cervical cancer.

2.Interferometric Reflectance Imaging for Single

Particle Detection

The Interferometric Reflectance Imaging Sensor (IRIS) is a low-cost, compact and simple to use biosensing platform developed at Boston University. IRIS has demonstrated high-throughput detection and quantification of protein-protein binding, DNA-protein

binding and DNA-DNA hybridization in real-time with high sensitivity and reproducibility [5]. Recent significant advancements have allowed us to detect and identify individual captured nanoparticles [6]. This new modality of IRIS is termed single-particle IRIS (SP-IRIS). SP-IRIS shines light from an LED source on nanoparticles bound to the sensor surface, which consists of a silicon dioxide layer on top of a silicon substrate (Figure 1a).

Interference of light reflected from the sensor surface is modified by the presence of particles producing a distinct signal that is captured by a conventional CCD camera. Single molecule detection/counting is a disruptive technology and digital detection of proteins in microarray format is poised to become one of the most powerful tools in the field of biomarker detection because of its enormous potential in diagnostics. The SP-IRIS platform

allows single molecule digital detection readout for different targets on one chip/test with up to 1000 times more sensitive (at atto-molar concentration) compared to conventional fluorescence systems [7].

Figure 1 SP-IRIS detection platform. a) Optical setup

which consist of LED lighting module, imaging objective

and CCD imaging camera. b) Illustration of SP-IRIS

sensor utilized for protein and nucleic acid detection. c)

A sample image showing response from individual

nanoparticles.

3.Clinical Application

We propose to apply the SP-IRIS platform to cervical cancer which is one of the most common and high

mortality rate cancers among women worldwide due to its few early stage symptoms, poor diagnosis and treatment possibility, and low survival rates. Early and accurate detection of cervical cancer is important especially in developing countries. We will translate emerging single-molecule counting or digital detection methods to develop a highly sensitive multiplexed protein assay. This technique will enable the detection of cervical

cancer at an early stage while providing valuable information about the high-risk lesions at the first screening of the patient.

References

[1] P.R. Srinivas, P.R. et al. “Trends in biomarker research for cancer detection,”

Lancet Oncol. 2, 698–704, (2011)

[2] M. Cretich, G. G. Daaboul, L. Sola, M. S. Ünlü, and M. Chiari "Digital detection of biomarkers assisted by nanoparticles: application to diagnostics," Trends in

Biotechnology, 33 (6), 343-351, (2015)

[3] A. Yurt, G. G. Daaboul, J. H. Connor, B. B. Goldberg, and M. S. Ünlü "Single

nanoparticle detectors for biological applications," Nanoscale, Vol. 4, No. 3, pp. 715 – 726, (2012)

[4] D. Walt, “Optical methods for single molecule detection and analysis,” Anal.

Chem. 85, 1258–1263, (2013) [5] O. Avci, N. Lortlar Ünlü, A. Yalcin, and M. S. Ünlü, “Interferometric Reflectance

Imaging Sensor (IRIS)-A Platform Technology for Multiplexed Diagnostics and

Digital Detection,” Sensors 15 (7), 17649-17665. (2015)

[6] G. G. Daaboul, "High-Throughput Detection and Sizing of Individual Low-Index Nanoparticles and Viruses for Pathogen

Identification," Nano Letters, Vol. 10, No. 11, pp. 4727-4731 (2010).

[7] M. Monroe et al. “Single nanoparticle detection for multiplexed protein diagnostics

with attomolar sensitivity in serum and unprocessed whole blood,” Anal Chem 85 (7),

3698-3706 (2013).


Rapid detection strategies for pathogens using functionalized nanoparticles

Uğur Tamer1

1Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, 06330 Ankara, Turkey

[email protected]

Abstract

The identification and the rapid detection of

bacteria and viruses have been one of the most important issues for diagnostic, environment and

food industry analysis. Many serious and even fatal

medical conditions result from bacterial or virus

infection or contamination. Additionally it is

possible to have faults by erroneously negative

tests. The created problems, however in term of

public health or economic and industrial

development, suggest the development of

alternative techniques of detection of these

microorganisms. Most accurate and reliable method

of indicating the presence of bacteria is culture

assay, but the conclusion of the culture assay require at least a period of 24 hours or more. It is

very difficult to detect these bacteria in a short time

which makes this subject very important all over

the world. Therefore, rapid antigen tests (RAT)

have been developed based on an antigen-antibody

reaction. Particularly, fast, simple and inexpensive

spot test applications based on the color change are

used for qualitative analysis of bacteria. To get

highly sensitive results in RAT test, it is necessary

to increase the number of bacteria in broth media

for at least 8 hours. However, the most important disadvantage of rapid antigen tests is low sensitivity

and low accuracy for the detection of pathogens.

Additionally it is possible to have faults by

erroneously negative tests. For quantitative

analysis, highly sensitive and accurate detection

methods are needed to reach a lower limit of

detection limits, instead of the measuring color

change.

Although optical methods such as surface enhanced

Raman Scattering (SERS) or fluorescence

measurements have been used for pathogen

detection, the construction of sensitive and reproducible substrate is still a challenge.

Especially, the paper microfluidics or microchip-

based measurement is a novel approach and will be

a powerful alternative to the expensive

conventional techniques that necessitate the

consumption of excess amount of sample and

materials. The present study aims to find out the

most proper bioactive chip preparation method to

develop rapid, sensitive and selective biosensor for

the quantitative determination of bacteria. This

presentation is mainly devoted to the tag based immunoassay technique without the need for

multiple washing process and SERS or fluorescence

labels will be placed in the system prior to analysis

(see Figure 1). In this work, we have synthesized

magnetic nanoparticles which are suitable for

immunomagnetic separation of microorganism. The surface of nanoparticles is modified with controlled

orientation of antibodies.

After immunomagnetic separation of bacteria from

matrix, labeled nanoparticles were immobilized to

the target bacteria on the surface of chip surface.

Then, SERS measurement was performed on the

test line. SEM image of the test line of lateral flow

immunoassay platform also indicated the

interaction of E.coli and gold particles with labeled

antibody (Figure 2).

Figure 1. Schematic diagram of the analytical

procedure

Figure 2. SEM image of the test line after E.coli interaction

The design, preparation and surface modification of

immunoassay platform could be useable for the

detection of of target bacteria from complex

matrices. The optimization strategies and the

analytical performance of the chip-based assays

will be presented.

Oral

Presentations


Biochar-Metalic Nanocomposite Based Glassy Carbon Paste Electrode Glucose

Biosensors

Derya Bal Altuntaş1*, Gökçen Akgül2, Eduardo Moreno Jiménez3 and Elena Diaz 4

1 Department of Bioengineering, University of Recep Tayyip Erdogan University, Faculty of Engineering , 53100, Rize, Turkey

2 Department of Energy Systems Engineering, Recep Tayyip Erdogan University, Faculty of Engineering.. 53100, Rize, Turkey 3 Universidad Autonoma de Madrid, Department of Agricultural and Food Chemistry, Madrid, Spain 4 Universidad Autonoma de Madrid, Department of Chemical Engineering, Madrid, Spain

*Presenter: [email protected]

Abstract

Biosensors are frequently used for the detection of

components such as drugs, harmful pathogens,

heavy metals or used for medical diagnoses by converting chemical and biological information

together into easily detectable signals [1]–[5]. As

reconstitution approach, a porous solid material as

conductive support or transducer is developed and

employed to the electrode surface. Novel researches

on support materials integrated with biochar [6]–[9].

Biochar is a carbonaceous material, derived from

biomass pyrolysis. For biosensor applications, some

properties of biochar may be improved by some

activations or modifications that would enhance

biochar applicability. The surface area and average

pore diameter of biochar can be developed by metal impregnation to excellent highly microporous

structures. In this work, electro-analytical properties

of metal impregnated-biochar was investigated as

support material with biochar carbon paste electrode

(BCPE). Biochar was derived from industrial tea

waste (BCTW). Biochar from tea waste was

impregnated with MgCl2 salt and calcinated. The structure contains MgO which dominates

microporosity of biochar (Figure 1-3).

The biochar has mostly micro-size particles alongside

nano ones. This simply nano-sized biochar was used with

glucose oxidase enzyme and in glassy carbon paste

electrode (GCPE) as biosensor support material contributing to the sensitivity of glucose biosensors.

Among other sensing platforms, glucose biosensors are

of special clinical and industrial significance because of

their role in monitoring blood-glucose levels in diabetes

mellitus, one of the most prevalent metabolic disorders

worldwide. Similar to other sensing platforms, glucose

biosensors have been the target to incorporate

nanomaterials, including metal nanoparticles (MNPs)

[10].

Figure 2. EDS image of Mg-impregnated biochar

Figure 3. EDS map of Mg-impregnated biochar

The electrochemical performances of The Mg-BCPE was tested in glucose biosensor transducers.

Acknowledgement: We are thankful to Universidad

Autonoma de Madrid, Department of Agricultural and

Food Chemistry and Chemical Engineering, Madrid,

Spain for the opportunity to use their laboratory facilities.

We gratefully acknowledge the financial support for

chemical analyses provided by Recep Tayyip Erdoğan

University, Scientific Research Projects Coordinator

Unit (BAP) (Project No: RTEU-2014.29.109.04.01 and

RTEU- 2015.53008.109.07.01).

References [1] R. Jain et al., Appl. Surf. Sci., 369, 151–158 (2016).

[2] M. Soler et al.., Biosens. Bioelectron. 66, 115–123

(2015). [3]H. Liu et al., Sensors Actuators, B Chem. 218,

60–66 (2015). [4]X. Wang et al., Biosens. Bioelectron.

81, 349–357 (2016).

[5] S. Han et al., Biosens. Bioelectron. 80, 265–272 (2016).

[6] D. Agustini et al., Talanta 142, 221–227 (2015). [7] A. Gevaerd et al., Mater. Sci. Eng. C 62, 123–129

(2016).

[8] P. R. Oliveira et al., Food Chem. 171, 426–431 (2015).

[9] T. M. Suguihiro et al, Bioresour. Technol. 143, 40–45

(2013). [10]A. A. Saei et al. Trends in Analy. Chem. 42,

216-227 (2013).

Figure 1. Mg-impregnated biochar

Oral Presentation – OP0203



A label-free electrochemical immunosensor based on ERGO

for determination of Hemoglobin A1c

Derya Koyuncu Zeybek1* and M. Özge Karaşallı1

1Department of Biochemistry, Faculty of Science and Arts, University of Dumlupınar, Kütahya, Turkey


Introduction

Diabetes Mellitus (DM) is a group of metabolic

diseases characterized by hyperglycemia affecting

about 150 million people around the world. For diagnosis and prevention of diabetes, measurement

of blood glucose value is the most commonly used

method. However, when blood glucose levels are

determined in this approach, which can fluctuate and

reflect a glucose level can be affected by the daily

diet and should be measured at regular intervals [1].

Hemoglobin A1c (HbA1c) or glycated hemoglobin

is defined as the gold standard in the diagnosis of

DM [2] The level of HbA1c reflects the average

blood glucose levels over 2-3 months and is not

affected by daily fluctuations of glucose levels. Several methods have been reported for

determination of HbA1c, such as boronate-affinity

chromatography, HPLC and capillary

electrophoresis [3-5]. Besides, electrochemical

immunosensors based on the specificity of antigen-

antibody interactions have been attracted increasing

attention owing to their significant advantages such

as simple procedure, high sensitivity, small

analytical volumes, low cost, easy miniaturization,

and rapid detection [6].

In this work, we reported a novel label-free

electrochemical immunosensor capable of sensitive detection of the DM biomarker HbA1c. The

immunosensor was fabricated based on

electrochemical reduced graphene oxide modified

glassy carbon electrode. Quantitative determination

of HbA1c was based on decreasing electrochemical

signal for Fe(CN)6-3/Fe(CN)6

-4 redox couple.

2. Experimental

2.1. Preparation of the GC/ERGO electrode

Graphene Oxide (GO) was prepared based on

modified Hummers method. 10 µl of GO (1mg/1mL ultrapure water) was dropped onto bare glassy

carbon electrode surface, and then dried at room

temperature. Subsequently, GO was

electrochemically reduced in 0.1 M KCl by cyclic

voltammetry.

2.2. Fabrication of the immunosensor

To immobilize anti-HbA1c antibody on GC/ERGO

electrode, an adequate amount of anti-HbA1c

antibody solution was dropped on the electrode

surface and incubated at 37°C (denoted as

GC/ERGO/HbA1cAb electrode). This procedure was followed by incubation with BSA% to block

nonspecific binding sites (denoted as

GC/ERGO/HbA1cAb/BSA electrode). Finally,

different concentrations of HbA1c antigen solutions

prepared in PBS (pH 7.4) were added onto

GC/ERGO/HbA1cAb/BSA electrode and incubated at 37°C (denoted as

GC/ERGO/HbA1cAb/BSA/HbA1c electrode).

2.3. Electrochemical Measurement

Electrochemical behaviors of proposed electrodes

were studied by CV and DPV in 10 mM pH 7.4 PBS

containing 5 mM Fe(CN)6-3/Fe(CN)6

-4 and 0.1 M

KCl.

HbA1c detection was performed via DPV in 10 mM

pH 7.4 PBS containing 5 mM Fe(CN)6-3/Fe(CN)6

-4

and 0.1 M KCl in the potential range from -0.1 to 0.6 V with a scan rate of 0.05 V s-1. The change or

relative change in peak current of the redox couple

was used to analyze the formation of antibody-

antigen complex.

3. Results

To characterize the fabrication process of the

immunosensor, CVs and DPVs were recorded at all

immobilization steps. According to the obtained

results, the GC/ERGO/HbA1cAB/BSA electrode

can be used for label-free detection of HbA1c.

The antibody coating time and antibody-antigen

incubation time were optimized. The inferences effects of some biomolecules were evaluated.

A linear relationship between DPV current change

and HbA1c concentration from 10 to 150 ng/mL

(correlation coefficient of 0.9999) was obtained.

4. Conclusions

In this study, we developed a novel label-free

electrochemical immunosensor for sensitive

determination of HbA1c.

5. References

[1] Pundir C.S., and Chawla S. 2014. Analytical Biochemistry 444,

47–56.

[2] Tanaka T., Kojiro I., Okochi M., Lim T-K.,Watanabe S.,

Harada M., and Matsunaga T. 2009. Analytica Chimica Acta

638 ,186–190.

[3] Tanaka T., Tsukube S., Izawa K., Okochi M.,Lim T-

K.,Watanabe S.,Harada M.,ve Matsunaga T. 2007. Biosensors

and Bioelectronics 22, 2051–2056.

[4] Little, Randie R., and Roberts, William L. 2009. Journal of

Diabetes Science and Technology 3(3), 446-451.

[5] Heli Siren , Laitinen P., Turpeinen U. and Karppinen P. 2002.

Journal of Chromatography 979, 201–207.

[6] Danilowicz C. and Manrique J.M. 1999. Electrochemistry

Communications 1(1), 22-25.



RNA SELEX for Green Fluorescent Protein and Application of Selected

Aptamer to Optic Biosensors

Dilber Ece Sezgin1* and Mehmet Mutlu2

1 Department of Biotechnology and Biosafety, Eskisehir Osmangazi University, 26480, Turkey

2 Department of Bioengineering, TOBB University of Economics and Technology, 06520, Turkey


Introduction

There has been growing interest in identification and

development of more specific and sensitive molecular

recognition elements [1]. Aptamers have distinct

advantages of over others including enzymes and

antibodies as molecular recognition elements [2]. The

distinguished molecular recognition properties of

artificially synthesized, short, single stranded DNA or

RNA aptamers come from the in vitro selection strategy, which is, used combinatorial chemistry, called SELEX

(Systematic Evolution of Ligands by EXponential

enrichment) [3-5]. A typical SELEX procedure

fundamentally consists of repetitive cycles of nucleic

acid library preparation, selection, amplification and

isolation of ligand binding sequences [6]. At the end of

the iterative cycles successful ligand binding sequences

are selected from chemically synthesized initial

oligonucleotide library of about 1014 different sequences.

Despite the analytic potential of aptamer molecules they

could not sufficiently come into use yet. This problem summarized as “thrombin problem” [7]. Potential of the

ability of construct any aptamer for any target limited by

the focusing only a few aptamer especially thrombin

aptamer usage. However thrombin aptamer, which is the

first protein binding aptamer, selected as a therapeutic

tool at first [8], it has become the major target in

aptamer-based bioanalytic applications. Its use in mass

sensitive bioanalytical sensing systems has brought some

limitations with and there has been a growing need for

any secondary confirmation about binding.

In this study, we investigate the applicability of GFP and its aptamer as a model aptamer system for biosensor

applications with a higher reliability because it also will

provide an additional validation for the system with

giving an optical signal besides the mass change signal.

Materials & Methods

Previously described, constructed and optimized RNA

aptamer library was used in this study. Selection steps of

SELEX cycles were carried out with an avidin-agarose

matrix based affinity column. Target molecule GFP was

biotinylated with a commercial kit (Sigma). In vitro

transcribed and purified RNA library was incubated with

GFP and binding sequences were separated, collected and purified with Sephadex-G25 column. Collected RNA

molecules after each selection step were reverse

transcribed and subsequently PCR amplified. Thiolated

avidin immobilization onto gold surfaces was carried out

via simple drop-coating. In order to confirm the avidin

immobilization, surfaces were examined with FT-IR.

Poly-(A) tail addition to the 3’ end of the aptamer

molecules obtained by SELEX was envisaged would be

ineffective on secondary structure and confirmed by M-

Fold. 3’ biotinylated poly-(T) oligonucleotides

immobilized on to avidin coated gold surfaces. Then

poly-(A) tail was added final selected aptamer pool

immobilized with poly-(T) oligonucleotides on the surface. Thus, selected aptamer molecules immobilized

on to the gold surface via interaction between poly-(A)

and poly-(T) sequences. Aptamer target molecule

interaction on the gold surface has been shown by

fluorescence microscopy.

Results &Discussion

After 8 SELEX cycle final aptamer sequences analyzed

with DNA sequence analysis. Accordingly, it could be

easily seen that all sequences pass whole selection steps

successfully. Unfortunately we could not be able to

reduce the pool to one specific sequence because of the limited number of SELEX cycles. We selected a number

of better variant final sequences of previously described

sequence that binding GFP. We determined a novel; fast,

reliable, easy and cheap affinity-SELEX method based

on known the strongest non-covalent avidin-biotin

interaction that can be further used for any protein

molecule. Utilization of thiolated avidin molecules was

made the immobilization step easier. Additionally simple

poly-(A) poly-(T) interaction was made the

immobilization step more reliable because secondary

structure of aptamers was not affected. Optical observations of interactions between selected aptamer

molecules and GFP were successfully demonstrated that

selected aptamer molecules and GFP could be used as a

model system at biosensor research in terms of it permits

the dual control of immobilization. Here we report the

first application of GFP aptamer system as a model

system for biosensor studies.

References

[1] McKeague, M., et al., Int J Mol Sci 2010, 11, 4864-4881.

[2] Balamurugan, S., et al., Analytical and bioanalytical chemistry

2008, 390, 1009-1021.D

[3] Ellington, A.D.; Szostak, J.W., Nature 1990, 346, 818-822.

[4] Robertson, D.L.; Joyce, G.F. , Nature 1990, 344, 467-468

[5] Tuerk, C.; Gold, L., Science 1990, 249, 505-510.

[6] James, W., Encyclopedia of analytical chemistry 2000.

[7] Baird, G.S., Am J Clin Pathol 2010, 134, 529-531.

[8] Bock, L.C., et al., Nature 1992, 564-566.



Glycophage Based Array as an Alternative Biosensor for Pathogen Detection

E. Çelik1,2*

1Department of Chemical Engineering, Hacettepe University, Beytepe, 06800 Ankara, Turkey

2Institute of Science, Bioengineering Division, Hacettepe University, Beytepe, 06800 Ankara, Turkey


Introduction

Printed carbohydrate microarrays (glycoarrays) have emerged in the last decade as powerful, high-throughput

tools for screening glycan-protein interactions and have

been applied in areas such as disease detection, drug

discovery and host-pathogen interaction studies.

However, glycoarray applications are still limited by the

expensive and complex methods available to synthesize

glycans or by the challenges in identifying and isolating

glycans from natural sources.

We have recently extended the power of phage display

technique for the production and selective enrichment of

phages that display N-linked glycoproteins [1] and further engineered these so called “glycophages” for use

in glycan microarray fabrication [2].

In this study, a simplified version of glycophage array

was developed with phages displaying E. coli O78 O-

antigen (a signature model molecule for a specific

pathogen), to study glycan binding proteins (GBPs) and

then optimized for specific phage production as well as

for array binding, probing and washing conditions.

Experimental

Helper phage VCSM13 (Stratagene) was produced in

E. coli TG1 and the glycophage particles were produced

in E. coli TG1ΔwaaL transformed with the phagemid pBAD-MBP4xDQNAT-CT::PglB and the plasmids

pMW07pglΔB or pMW07-O78, as described previously

[2]. For array studies, high binding, half-area 96-well

microtiter plates (Corning) were coated with 1-20x1011

glycophage particles and probed, blocked and washed

using various strategies. The absorbance in each well

was read at 492 nm after treatment with the o-

Phenylenediamine dihydrochloride (OPD) substrate

(Sigma).

Results and Discussion

Phage titers of ~2x1011 PFU per mL of culture

supernatant was obtained. When the phage preparations

were analyzed by immunoblotting, a ladder of higher molecular weight bands were detected by the anti-Ec-

OAg (O78) antiserum. The high-molecular-weight bands

were absent in the samples obtained from cells that were

not infected with helper phage, lacked the phagemid, or

lacked the O-antigen biosynthesis pathway as negative

controls, suggesting that O78 polysaccharide was

covalently linked to MBP4xDQNAT-CT fusion protein

displayed on the phage particles. After optimized array

binding, probing and washing conditions, the signal-to-

noise ratio was higher than 2.5.

Conclusion

The advantages of glycophage-based arrays presented

here, include the low cost and scalability of phage/glycan

production, which are biosynthetic processes involving

the cultivation of recombinant E. coli cells, and the ease

with which glycophages can be recovered from the

culture supernatant without laborious purification steps.

Furthermore, an array of O-antigens, which are the

signature surface molecules of gram-negative bacteria,

displayed on the phage particles provide the basis of a

high-throughput technique for pathogen detection.

References

[1] Çelik, E., Fisher, A.C., Guarino, C., Mansell, T.J., DeLisa, M.P. Protein Science., 19, (2010) 2006-2013.

[2] Çelik, E., Ollis, A.A., Lasanajak,Y., Fisher, A.C.,

Gur, G., Smith D.F., DeLisa, M.P. Biotechnology.

Journal, 10, (2015) 199-209.

Acknowledgments- Marie Curie FP7 Career Integration

Grant under REA grant agreement # 322096 and

UNESCO-L’Oréal Young Women in Science Award.



Paper-based Sensors as Optical Chiral Discrimination Platform

Erhan Zor1*, M. Esad Sağlam2 and Haluk Bingol3

1 Department of Science Education, Necmettin Erbakan University, Konya, Turkey

2 Institute of Science, Necmettin Erbakan University, Konya, Turkey 3 Department of Chemistry Education, Necmettin Erbakan University, Konya, Turkey


Introduction

Chirality, defined as the geometric property of a

structure of being non-superimposable onto its mirror

image, is a fundamental characteristic of life processes

[1]. The majority of bioactive materials and drugs are

mainly composed of enantiomers of chiral molecules.

For living systems, one enantiomer may influence

desirable property whereas the other may often displays

a different biochemical activity or may cause serious

side-effects [2]. Therefore, the development of simple

and robust sensors for discriminative sensing of enantiomers of chiral substances is enormously

important for drug discovery and pharmaceutical

industry. Within this respect, paper-based (bio)sensing

platforms which permit the performance of low-cost and

fast response with good robustness have increased great

attention for applications in diagnostics, environmental

monitoring and food safety. Cost-efficient and eco-

friendly green materials and large-scale processes are

attracting intensive research and commercial interests

because they enable fabrication of a range of disposable

devices for consumers [3].

Figure 1. As-prepared wet nanopaper. Inset is SEM

image of dried nanopaper.

With the recent advances in nanomaterials, great effort

has been devoted to the development of miniaturized

analytical platforms for paper-based optical sensing

platforms [4]. However, paper-based platforms has been

scarcely used for optical (bio)sensing applications and

even no published study exists for optical chiral

discrimination explored by paper-based systems to date.

Hence, we sought to design, fabricate, and test simple, disposable and versatile chiral discrimination platforms

based on paper. Herein, we describe nanoparticle-

embedded paper-based platforms that exhibit plasmonic

or photoluminescent properties which can be used as

optical chiral discrimination platform. We tested

different papers such as common paper, filter paper,

cellulose acetate membrane, cooking paper and

nanopaper (Figure 1) at various configurations including

spots and signs (sensor) that are printed on papers using

a filtration method or commercial inkjet printer (Figure

2). It can be seen that color changes from red to violet in

the presence of only L-enantiomer for metallic

nanoparticles and also photoluminescent quenching

effect is observed in the case of carbon quantum dot.

(1) (2) (3)

Figure 2 Nanoparticles (NPs) embedded membrane (by

filtration) for discrimination of D-/L-enantiomer (1).

Ink-jet printed enantioselective carbon quantum dot

signs (2) and spots (3) on transparent nanopaper.

Taking advantage of the inherent chirality of metallic

NPs and chiral carbon/graphene quantum dots, we

herein point out simple paper-based sensor platforms

that can be used as a convenient colorimetric probe to discriminate enantiomers of chiral molecules, which can

be a promising model and platform for discrimination of

other biologically important enantiomers of chiral drugs

and molecules.

Acknowledgements: We express our deep thanks to the

Scientific and Technological Research Council of

Turkey (TÜBİTAK) for financial support (215Z222).

4. References

[7] Wattanakit et al., Nature Commun., 2014, 3325, 1-8.

[8] Zor et al., Biosens.Bioelectron. 42, 2013, 321–325.

[9] Huang et al., ACS Nano, 2013, 7 (3), 2106–2113.

[10] Morales-Narvàez et al., ACS Nano, 2015, 9 (7),

7296–7305.



Next Generation Biosensors:

Near-Infrared Fluorescent Single-Walled Carbon Nanotubes

F. Sen1*

1 Sen Research Group, Department of Biochemistry, Dumlupinar University, Kütahya, Turkey


Abstract

Single-walled carbon nanotube based biosensors are

particularly attractive for biomedical applications,

because they exhibit a highly efficient fluorescent

signal in a near-infrared region where there is

minimal interference from biological media.

Although single-walled carbon nanotubes have been

used as highly sensitive detectors for various

compounds, their use as in vivo biomarkers requires

the simultaneous optimization of various parameters, including biocompatibility, molecular

recognition, high fluorescence quantum efficiency

and signal transduction. Adrressed herein, a new

type of near infrared- fluorescent single-walled

carbon nanotubes sensors have been developed and

polyethylene glycol ligated copolymer stabilizes

their fluoresecent efficiency in solution, enabling

intravenous injection into mice and the selective

detection of local nitric oxide concentration with a

very low detection limit. After localization within

the organelles, it is possible to follow the transient inflammation using nitric oxide as a marker and

signalling molecule. Finally, we demonstrate that

alginate-encapsulated single-walled carbon

nanotubes can function as implantable inflammation

sensors for nitric oxide detection.

Figure 1 DNA based carbon nanotube biosensor

References

[1] Kim, J. H. et al. The rational design of nitric oxide

selectivity in single-walled carbon nanotube near-

infrared fluorescence sensors for biological detection.

Nature Chem. 1, 473–481 (2009).

[2] Zhang, J. Q. et al. Single molecule detection of nitric

oxide enabled by d(AT)15 DNA adsorbed to near

infrared fluorescent single-walled carbon nanotubes. J. Am. Chem. Soc. 133, 567–581 (2011).

[3] Heller, D. A. et al. Optical detection of DNA

conformational polymorphism on single-walled carbon

nanotubes. Science 311, 508–511 (2006).

[4] Ahn, J. H. et al. Label-free, single protein detection

on a near-infrared fluorescent single-walled carbon

nanotube/protein microarray fabricated by cell-free

synthesis. Nano Lett. 11, 2743–2752 (2011).

[5] Barone, P. W., Baik, S., Heller, D. A. & Strano, M.

S. Near-infrared optical sensors based on single-walled

carbon nanotubes. Nature Mater. 4, 86–U16 (2005).

[6] Liu, Z. et al. Drug delivery with carbon nanotubes

for in vivo cancer treatment. Cancer Res. 68, 6652–

6660 (2008).

[7] Heller, D. A. et al. Multimodal optical sensing and

analyte specificity using single-walled carbon

nanotubes. Nature Nanotech. 4, 114–120 (2009).

e-

h+

hν

e-

h+

e-

h+

hν



Nanopore-integrated microfluidic biosensors with single molecule

detection capability

F Dogan1,2,3*, F. Citak2, T. Albrecht3, J. B. Edel3 and M. Winterhalter2

1Nanoscience and Nanotechnology Section, Osmangazi University, Eskisehir, 26480, Turkey

2Faculty of Science and Engineering, Jacobs University, Bremen 28759, Germany

3Department of Chemistry, South Kensington Campus, Imperial College London, London, SW7 2AZ, UK


1. Introduction

Nanopores, both solid-state and biological ones, are

excellent tools to detect single molecules with high

precision. They are being utilized in many applications

so far including DNA-RNA sensing, epigenetics, DNA-

protein interactions and even antibiotic resistance [1, 2].

Detection using nanopores has numerous advantages over conventional techniques (e.g. gel electrophoresis)

and these are label-free detection, use of low sample

volumes and the ability to extract single molecule

information. A nanopore can be either biological or

fabricated on a solid-state microchip. Biological

nanopores exists naturally and can be experimentally

inserted into artificially created lipid bilayers, allowing

the electrophysiological study of the ionic current

across. The list for their utility can also be extended to

antibiotic research [3]; searching into a global problem

faced today: Multi-drug resistance of Gram-negative bacteria.

Figure 1. Schematic of biological nanopore-based

biosensor-antibiotic permeability assay.

Antibiotic research is important, because an unfortunate

end to the golden age of antibiotic era is approaching

and the world is in urgent need of new antibiotics, new

assays and new techniques to understand the resistance

and stop it if not too late. The problem clearly

intensifies from day to day. To address the issue, a

European Union initiative has recently been launched;

‘New Drugs for Bad Bugs’ (ND4BB)-Translocation

(www.translocation.eu) Project by Innovative

Medicines Initiative (IMI) [4]. The project is devoted to understand the permeability of antibiotics to cross the

cell wall of Gram-negative bacteria and to reach their

target. As a part of the Translocation project, we have

developed an on-chip permeability assay characterizing

single biological pores-porins that exist in the outer cell

wall of Gram-Negative bacteria and are responsible for

the uptake of several hydrophilic molecules, nutrients

and antibiotics- and addressing how single antibiotic

molecules may interact with the porin.

As for solid-state nanopores, many non-porous

semiconducting and insulating material (e.g. Si, SiO2,

graphene, ploymers) can be employed for nanopore chip

fabrication. To date, there have been numerous reports

over the material selection and the sensing ability of the

solid-state nanopores. Next appears to increase its utility by constituting an engineered device which can perform

multiple tasks within the capability of a single chip.

2. Devices and Detection Concept

Here, we present compact nanopore-integrated

microfluidic devices with single molecule detection

capability. Both solid-state and biological nanopores

(single one of them) are integrated into a single

microfluidic channel for the detection of single DNA

molecules in flow and the investigation of antibiotic

permeability, respectively (Figure 1, Figure 2).

Figure 2. Schematic of the device, a photography image and representative data for detection signal.

The detection concept is simple: upon the application of

the electric field, an ionic pathway is created from the

channel to the back side of the device through a single

nanopore. As shown in Figure 2c, this is recorded as a

stable current trace due to the passage of the electrolyte

ions. Once DNA is added to the channel, DNA blocks

the pore for a certain amount of time and current blockage events are observed, referring to individual

DNA translocations. The shape of the events changes

depending on the charge, conformation and size of the

molecule inside the pore.

3. Conclusion

In conclusion, these studies demonstrate that nanopore-

integrated microfluidic sensors can be used for single

molecule detection in flow, successfully.

4. References

[1]. Miles BN et al. Chemical Society Reviews. 2012.

[2]. Dekker C. Nat Nano. 2007;2(4):209-15.

[3]. Nestorovich EM et al. PNAS. 2002;99(15):9789-94.

[4]. Kostyanev T et al. The J. of An. Chem. 2016;71(2):290-5.



http://www.translocation.eu/


Pattern-free, CMOS compatible infrared-absorption-spectroscopy surfaces for

sensing bio-molecule monolayers

G. Bakan1,2*, S. Ayas2, E. Ozgur2*, K. Celebi and A. Dâna2

1Department of Electrical and Electronics Engineering, Antalya International University, Antalya, Turkey

2UNAM, Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey


1.Introduction

Infrared (IR) vibrational spectroscopy is one of the

widely used tools in chemistry and biology for

characterization of materials [1]. Absorption signatures

of materials due to molecular vibrations can be sensed

in the far-field signals (reflection or transmission

spectrum) when a broadband infrared light source is

used. Current infrared measurement techniques such as Fourier Transform Infrared Spectroscopy (FTIR),

however, require large amounts of molecules for

measureable absorption signals. Increasing the near-

field intensities in the vicinity of small amount of probe

molecules can result in similar absorption signals. This

technique is known as Surface Enhanced Infrared

Absorption Spectroscopy (SEIRA) and commonly uses

plasmonic surfaces for the field enhancement [2].

Depending on the vibrational bands to be enhanced, the

geometry of nano-patterns has to be tuned. Here, we

demonstrate pattern-free surfaces which can consist of CMOS compatible materials such as Al and Si and

provide large absorption signals when coated with

monolayers of biological and chemical molecules [3].

2. Results

Electric field intensity (|E|2) enhancement factor is

almost zero on the surface of a metal and increases up to

4 at a distance quarter wavelength (λ/4) away from the

surface when the metal is exposed to infrared light.

Therefore, when a thin layer of probe material, such as a

monolayer bovine serum albumin (BSA), is positioned quarter wavelength away from the surface, the

absorption signal is expected to be enhanced by a factor

of 4 compared to the absorption of a free-standing layer.

2.1. Simulations

The resonance wavelength, at which the electric field is

enhanced to its maximum, is determined by the optical

properties of the dielectric material between the metal

and the probe material. The maximum enhancement

factor of 4 can be achieved when air (n=1) is used as the

dielectric material. However, leaving an air gap between

the metal and a thin layer of probe material complicates the fabrication process. Alternatively, IR-transparent

materials can be used as the dielectric material for an

easy fabrication at the expense of the enhancement

factor. For example, enhancement factors for some of

the IR transparent materials are 3.95 for CaF2 (n=1.25),

3.7 for amorphous silicon (a-Si) (n=3.3) (Figure 1), and

3.6 for chalcogenides (Ge2Sb2Te5, n=3.6).

Figure 1 (a) Illustration of the sensor surface with

atop 5 nm PMMA layer as the probe material.

The enhancement factor at λ~5.77 µm as a

function of the vertical position is shown on top of the illustration. (b) Simulated absorption

signal of the PMMA layer.

2.2 Experiments

The surfaces are fabricated using both plasma-

enhanced-chemical-vapor-deposition and electron-beam

evaporation of a-Si on 80-nm-Al coated Si substrates.

For proof of concept experiments, the surfaces are

coated with 5 nm PMMA layer, used as the probe

material to test the sensing performance of the surfaces.

The a-Si thickness is chosen to tune the surface’s first

order resonance to be close to the PMMA’s major vibrational band at 1732 cm-1 (λ~5.77 µm). The

measured signal intensities are ~6 % after background

subtraction. The sensing performance of the surface is

preserved up to extreme angles of incidence (75°) for

both p- and s-polarizations. The surfaces are also

studied for other dielectric materials and tested with

other biological and chemical monolayers.

3. Conclusions

We propose a pattern-free, CMOS compatible surface

structure for sensing monolayers of bio-molecules using

infrared absorption spectroscopy. The surfaces can be fabricated with low cost, on large area, and can provide

large absorption signals for very thin probe materials.

Acknowledgements: This work is supported by

TUBITAK grant #114E960 and EU FP7:People-IAPP

NanoBacterPhageSERS.

4. References

[1] Kendall, C. et al., Analyst 134, 1029–45 (2009) [2] Adato, R. & Altug, H., Nat. Commun. 4, 2154 (2013). [3] Ayas, S. et al., ACS Photonics 3, 337 (2016).

2

λ (µm)

4 6 8 10

a-Si

(400 nm)

2 40|E|2/|Eo|

2

Monolayer

(b)

Al

(a)

Sig

nal

(%

)

0

-1

-2

IR light



Simultaneous Electrochemical Determination of Ascorbic acid, Dopamine and

Uric Acid Based on Gold Nanoparticles-Graphene oxide-Poly-(2,6-

Pyridinedicarboxlic Acid) Modified Electrode

Gözde Aydoğdu Tığ*1, Gülendem Günendi1 and Şule Pekyardımcı1

1 Department of Chemistry, Faculty of Science, Ankara University


1. Introduction

Ascorbic acid (AA), dopamine (DA) and uric acid (UA)

play critical roles in human metabolism, central nervous

and renal systems. Abnormal concentration levels of

AA, DA and UA can cause serious health problems

such as mental illness, cancer, Parkinson’s disease,

hyperuricaemia and gout [1, 2]. AA, DA and UA

coexist in human body fluids, thus simultaneous

determination of these substances is important not only

searching their physiological functions but also

diagnosing diseases. However, the oxidation potentials of these compounds are too close to be separated at bare

electrodes for their overlapping signals.

In this study, we propose a novel and simple strategy for

simultaneous determination of AA, DA and UA based

on gold nanoparticles (AuNPs), graphene oxide (GO)

and poly(2,6-pyridinedicarboxlic acid) (P(PDCA))

modified glassy carbon electrode (GCE).The modified

electrode shows excellent selectivity, sensitivity and

reproducibility for the determination of AA, DA and

UA with lower detection limits.

2. Materials and Methods

All electrochemical measurements were carried out by using an AUTOLAB-PGSTAT 302N electrochemical

analyzer connected with a three-electrode cell stand

(Bioanalytical Systems, BAS, Inc., USA). A

conventional three-electrode system consist of the bare

or modified GCE as working electrode, a platinum wire

as counter electrode, and Ag/AgCl (3 mol L−1 NaCl,) as

reference electrode. The CVs and DPVs were analyzed

by using NOVA 11.0 software (ECO Chemie). The

AuNPs were electrodeposited on the surface of GCE

with 0.6 mmol L−1 HAuCl4 solution in H2SO4 0.5 M for

15 cycles in the potential range of 0.2 to +1.2 V and a scan rate of 100 mVs–1 [3]. A freshly prepared monomer

solution containing 0.1 mol L−1 KCl and 1.0 mmol L−1

PDCA was prepared and then mixed with GO (1 mg/1

mL) and sonicated for 1 h to form homogeneous

mixture. The P(PDCA)-GO composite film was

fabricated on the electrode surface by CV scanning of

GCE/AuNPs in the above mixture solution from 0.0 V

to +2.0 V at a scan rate of 60 mVs–1 for 10 cycles.

3. Result and Discussion

In this study, GCE/AuNPs/P(PDCA)-GO was

constructed and this electrode was used for the

electrochemical determining of AA, DA and UA for the

first time. The composite film was characterized by

scanning electron microscopy (SEM). Electrochemical

behavior of GCE/AuNPs/P(PDCA)-GO was

investigated by using CV and EIS and compared with

those of the bare GCE. Fig. 1 depicts the DPV response

of AA, DA and UA at bare GCE (a), GCE/P(PDCA)

(b), GCE/AuNPs (c), GCE/AuNPs/P(PDCA) (d),

GCE/P(PDCA)-GO (e) and GCE/AuNPs/P(PDCA)-GO

(f) electrodes. As shown in curve f,

GCE/AuNPs/P(PDCA)-GO resolved the merged voltammetric peak into three well-defined peaks. The

peak separations between AA and DA, AA and UA, DA

and UA were 161 mV, 336 mV and 175 mV,

respectively. Moreover, a remarkable increase in each

peak current was observed with comparison to the other

modified electrodes. The effect of pH and pre-

concentration time were selected as 3.0 and 2.0 min,

respectively. Furthermore, the reproducibility,

repeatability, stability and applicability of the analysis

in urine samples were also investigated. These results

showed that the proposed method is a promising tool for

simultaneous determination of AA, DA and UA in urine.

Figure 1 The DPVs responses of 100 µmol L−1 AA,

10 µmol L−1 DA and 25 µmol L−1 UA in 0.1

mol L−1 PBS (pH 3.0) at the bare GCE (curve

a) and modified electrodes (curve b-f)

4. References

[1] X. Niu, W. Yang, H. Guo, J. Ren, F. Yang, J. Gao, Talanta, 99

(2012) 984-988.

[2] G. Zhang, P. He, W. Feng, S. Ding, J. Chen, L. Li, H. He, S.

Zhang, F. Dong, Journal of Electroanalytical Chemistry, 760

(2016) 24-31.

[3] R.-S. Saberi, S. Shahrokhian, G. Marrazza, Electroanalysis, 25

(2013) 1373-1380.



A Novel Fiber based MALDI Probe for Selective Detection of Ciprofloxacin

G. Aylaz1*, A. Tevlek2, Ö. Çelikbıçak3 and M. Duman1

1 Nanotechnology and Nanomedicine Division, Hacettepe University

2 Department of Bioengineering, Hacettepe University

3 Department of Chemistry, Hacettepe University


Abstract Matrix-assisted Laser Desorption/Ionization Mass

Spectrometry (MALDI-MS) has become a popular

surface-based technique to analyze peptides, proteins and

many other molecules with biological origin. Large molar

excess of a matrix, which is usually a organic acid, is used

for increasing the ultraviolet (UV) absorbing. In MALDI,

the analyte is first co-crystallized with matrix compound,

and then analyte-matrix mixture evaporates with laser.

The matrix is an important point for absorbing the laser

energy and transporting the analyte to the detector [1][2].

New generated fibers have been produced with

electrospinning technique. Electrospun fibers have already

been used in MALDI as substrates. Different polymer

solutions travel by high electric field. When polymer

solution is exposed to the electrical effect, solvent of the

solution evaporates quickly and charged polymer is jet-

transferred to the metal collector. The feed rate of polymer

solution, the distance of solution input point and collector,

the electric field range, solvent and polymer type are the

important parameters for diameter of electrospun fibers

[3].

Molecularly Imprinted Polymer (MIP) technology is a

new approach for enrichment, selective detection studies

and separation of molecules from undesired molecules.

Monomer, initiator, cross linker and template molecule

are mixed at optimum conditions for producing. After the

polymerization proses, the template molecule is washed

away with desorption solution for creating template

molecule imprinted polymer [4].

In this study, Ciprofloxacin (CPX) which is antibiotic was

imprinted. The films and electrospun fibers were

synthesized with Poly L Lactic Acid (PLLA) polymer and

they were characterized by Fourier transform infrared

spectroscopy (FTIR) and Scanning Electron Microscopy

(SEM). Some type of films and fibers were produced with

2,5-Dihydroxybenzoic acid (DHB) because to seek

whether increasing of the ionization efficiency in

MALDI-MS or not.

As a result, signal/noise ratio (S/N) of CPX on PLLA

films in MALDI was higher than PLLA fibers. By the

way, using MIP has risen the S/N ratio. DHB effect of the

S/N ratio has not hold significant for detection CPX on

films and fibers in existence MIPs.

Figure 1.MALDI-MS Spectrums of CPX on MIP modified

electrospun PLLA fiber (a) and MIP modified electrospun

PLLA fiber with %2,5 DHB Matrix.

References

[1] Harrison Alex G, “Chemical Inonization Mass

Spectrometry”.CRC Press,2nd Edition,1992.

[2] Hansell, Claire. “Enter the Matrix.” Nat Meth (2015).

doi:10.1038/nmeth.3527.

[3] Md. Abdul Awal,” Development Of Continuous Bio-Composite

Fibres”, Doctor of Philosophy

Faculty of Forestry, University of Toronto, 2012.

[4] Giuseppe Vasapollo, Roberta Del Sole, Lucia Mergola, Maria

Rosaria Lazzoi, Anna Scardino,

Sonia Scorrano and Giuseppe Mele,”Molecularly Imprinted

Polymers: Present and Future Prospective” International Journal

of Molecular Sciences,2011,12,5908-5945.




Rapid Detection of Disease Biomarkers with ATR-

FTIR Spectroscopy

Günnur Güler

1* and Ercüment Karasulu

1

1Department of Biosimilar Drugs, Center for Drug R&D and Pharmacokinetic Applications, ARGEFAR, Ege

University, Izmir, Turkey


1. Introduction

Infrared (IR) spectroscopy is a molecular vibrational

spectroscopy that yields information about the

biochemical composition, bonding properties and molecular structure (and environment) of biological

macromolecules. It is a time-saving and non-destructive

technique which requires low setup and running cost.

Therefore, it is frequently used for analyzing of tissue,

cell and body fluids which composed mainly of

proteins, lipids, carbohydrates and nucleic acids (DNA,

RNA and microRNA). Any changes in these biological

macromolecules are considered to be biomarkers for

diagnosis and monitoring of some human diseases (i.e.,

cancer); therefore, IR technique can be used for rapid,

simple and label-free detection of disease biomarkers

[1-4].

2. Experimental

The current talk deals with the theoretical and

experimental aspects of attenuated total reflection-

Fourier transform infrared (ATR-FTIR) spectroscopy

for the study of synthetic nucleic acids (DNA, RNA and

microRNA), cell lines as well as tissues in the mid-IR

spectral region of 4000-700 cm-1. Measurements of the

samples were performed with a IRTracer-100 FTIR

spectrometer (Shimadzu, Japan) combined with an ATR

accessory and equipped with a DLATGS detector. A

total of 128 scans were averaged for each interferogram at 4 cm-1 resolution.

3. Results

FTIR enables to follow the proteomic, lipidemic and

metabolic changes in real samples (i.e., cell, tissue,

body fluids) induced by diseases or drug treatment. On

the basis of the FTIR data of rat tissues (Fig. 1), a peak

of the protein amide I band can be seen around 1650

cm-1 and the amide II band appears around 1550 cm-1.

Lipid CH2 and CH3 signals appear between 2800 and

3000 cm-1 region while lipid ester carbonly groups are

detected around 1740 cm-1. Nucleic acid signals arising

from base, sugar and phosphate molecules are detected in the 1800-800 cm-1 region. Therefore, this technique

can be used for deciphering of disease biomarkers.

ATR-FTIR is a well-established tool for fast, label-free

and cost-effective detection of biomolecular targets (i.e.

nucleic acids) and requires a small amount of sample (a

few µl) without particular sample preparation. With

tracking of IR spectral changes, it is possible to observe

alterations in the molecular structure as well as

expression level of biological macromolecules in real

samples. For instance, IR spectra provide fingerprint-

like signatures of nucleic acids originating from base,

sugar and phosphate groups. Thus, the ATR-FTIR

technique as a high-sensitive optical biosensor can be a potential alternative tool which paves the way for the

rapid, simple and label-free detection of disease

biomarkers in early clinical diagnosis and biomedical

research area.

Figure 1: ATR-FTIR absorbance spectra of rat tissues

(unpublished data).

4. References

[1] Güler, G., Gärtner, R.M., Ziegler, C. and Mäntele,

M. (2016). “Lipid-Protein Interactions in the Regulated Betaine Symporter BetP Probed by Infrared

Spectroscopy.” The Journal of Biological Chemistry

291(9): 4295–4307.

[2] Kaplan, M., Kılıc, T., Guler, G., Jihane, M., Amine,

A., Ozsoz, M. “A novel method for sensitive microRNA

detection: electro polymerization based doping.”

Biosensors and Bioelectronics, in Press, accepted

manuscript,

http://dx.doi.org/10.1016/j.bios.2016.09.050.

[3] Movasaghi, Z., Rehman, S. and Rehman,I. (2008).

“Fourier Transform Infrared (FTIR) Spectroscopy of

Biological Tissues.” Applied Spectroscopy Reviews 43(2): 134–79.

[4] Banyay, M., Sarkar, M. and Gräslund, A. (2003). “A

Library of IR Bands of Nucleic Acids in Solution.”

Biophysical Chemistry 104(2): 477–88.




Electrochemical Detection of Interaction between Plantago Anatolica and

DNA by Using Disposable Biosensors

Hasret Subak1,2*, Abdullah Dalar3 and Dilsat Ozkan-Ariksoysal1*

1*Ege University, Faculty of Pharmacy, Analytical Chemistry Department, Izmir, Turkey

2Yuzuncu Yil University, Faculty of Pharmacy, Analytical Chemistry Department, Van, Turkey 3Yuzuncu Yil University, Faculty of Pharmacy, Pharmaceutical Botany Department, Van, Turkey


Introduction

Plantago anatolica is an endemical and ethnomedical

traditional folk medicine used in eastern anatolia for

analgesic purposes. In this study, the plant extract (as

lyophylisated powder) was prepared in different

solvents such as n-hekzan, acetone, ethanol, methanol or

pure water.

There has still been groving interest in studying the

recognition and quantification of the compound-DNA

interactions by using electrochemical biosensors

because they give good information about the

interaction mechanism of the drug and DNA with their fast, simple and cost-effective methodologies.

In this study, the electrochemical behavior of the plant

extract was monitored and the effect of this extract on

DNA was investigated by using biosensor technology.

The interaction mechanism of the extract was also

studied and evaluated with bare or nanomaterial

modified disposable carbon electrodes by using

differential pulse voltammetry (DPV). Thus, the optimal

experimental parameters were determined and obtained

results showed that newly-developed biosensor could be

used for the rapid, cost effective and sensitive detection

of plant extract–DNA interaction.

Figure 1 Schematic illustration of the

electrochemical sensor for the detection of

Plantago anatolica and DNA interaction.

References

[1] Ozkan-, D. Karadeniz-,H. Erdem, A. Mascini,M.

Ozsoz, M. Journal of Pharmaceutical and Biomedical

Analysis 35 (2004) 905.

[2] E. Palecek, M. Bartosik, Chemical Reviews. (2012),

112, 3427.

[3] D. Ozkan-Ariksoysal, B. Tezcanli, B. Kosova, M.

Ozsoz, Anal. Chem. (2008) 80, 588.

[4] Ceren Sengiz, Gulsah Congur, Ece Eksin, Arzum

Erdem, Electroanalysis 2015,27, 1855 –1863.

[5] F. Lucarelli, G. Marrazza, A. P. F. Turner, M.

Mascini, Biosensors & Bioelectronics. (2004), 19, 515.

[6] Y.U. Kayran, D.Ozkan-Ariksoysal, B.Tezcanli, B.

Kosova, Mehmet Ozsoz, Electroanalysis (2013), 25, 12,

2668.



Electrochemical Impedimetric Immunosensor Based on Gold Nanoparticles

Functionalized Screen-Printed Gold Electrode for Carcinoembryogenic Antigen

(CEA) Tumor Marker Detection

Ş. Sultan1*, Ç. K. Rabia1 and K. Merve2

1 Department of Bioengineering, Yıldız Technical University, İstanbul, Turkey

2 Department of Medical Biology, S¿leyman Demirel University, Isparta, Turkey


Abstract

Impedimetric immunosensors are constructed with

antibody immobilization of working electrode and their

working principle is that occuring a correlation between

antigen concentration and obtained resistance after an

electrochemical Ab-Ag interaction. EIS is generally used to characterize these type detections in biosensor

applications [1]. Electrochemical impedimetric

biosensors have significant advantages for sensitive

detection of cancer biomarkers which are being smaller,

faster, more sensitive, cheaper devices, without

radiation hazards, allowing label-free, concurrent

detection, simple production, less time consuming, rapid

detection, having longer shelf life, and not complicated

procedure. These properties will substantially get easier

early dianostic of cancer at beginning phases.

Carcinoembryogenic antigens which are cell surface

glycoproteins [2] are used as an important biomarker in human serum associated with colorectal, lung, breast

cancer and ovarian carcinoma [3, 4]. CEA

quantification analysis with electrochemical impedance

spectroscopy promotes early diagnosis of cancer which

is crucial for the successful treatment of the disease and

increases health standards of people[5]. The gold layer

has various advantages during immobilization process

thereby the easy adsorption of biomaterials relates to

hydrophobic and thiol–gold interactions. In recent years,

gold nanoparticles (AuNPs) are commonly used to

enhance more sensitive electrochemical immunoassay for immobilization of antibody. AuNPs provide strongly

adsorbtion of antibody on working electrode during

immobilization due to its large specific surface area,

good biocompatibility, surface free energy of nanosized

particles [6, 7]. AuNPs facilitate electron transfer

between redox proteins and electrode surfaces, provide

effective mass transport in electrochemical biosensor

applications as making closer redox protein

(monoclonal CEA antibody) to the electrode via

nanosized structure. In the other words, AuNPs is a

desirable intermediator for immobilization of antibodies

[8]. In this study, the gold electrode is modified with thiol and AuNPs to develop an impedimetric biosensor

to detect CEA as an important cancer biomarker.

References

[1] M.I. Prodromidis, Impedimetric immunosensors-A

review, Electrochimica Acta, 55 (2010) 4227-4233.

[2] M. Taheri, U. Saragovi, A. Fuks, J. Makkerh, J.

Mort, C.P. Stanners, Self recognition in the Ig superfamily - Identification of precise subdomains in

carcinoembryonic antigen required for intercellular

adhesion, Journal of Biological Chemistry, 275 (2000)

26935-26943.

[3] X.L. Li, R. Yuan, Y.Q. Chai, L.Y. Zhang, Y. Zhuo, Y.

Zhang, Amperometric immunosensor based on toluidine

blue/nano-Au through electrostatic interaction for

determination of carcinoembryonic antigen, Journal of

Biotechnology, 123 (2006) 356-366.

[4] J. Wu, J. Tang, Z. Dai, F. Yan, H. Ju, N. El Murr, A

disposable electrochemical immunosensor for flow

injection immunoassay of carcinoembryonic antigen, Biosensors & Bioelectronics, 22 (2006) 102-108.

[5] J. Wang, Electrochemical biosensors: Towards point-

of-care cancer diagnostics, Biosensors & Bioelectronics,

21 (2006) 1887-1892.

[6] S.Y. Xu, X.Z. Han, A novel method to construct a

third-generation biosensor: self-assembling gold

nanoparticles on thiol-functionalized poly(styrene-co-

acrylic acid) nanospheres, Biosensors & Bioelectronics,

19 (2004) 1117-1120.

[7] D. Hernandez-Santos, M.B. Gonzalez-Garcia, A.C.

Garcia, Metal-nanoparticles based electroanalysis, Electroanalysis, 14 (2002) 1225-1235.

[8] J.M. Pingarron, P. Yanez-Sedeno, A. Gonzalez-

Cortes, Gold nanoparticle-based electrochemical

biosensors, Electrochimica Acta, 53 (2008) 5848-5866.

Poster Presentation – PP0242


(𝑎𝑑𝑠)

Acetone gas sensor based on ZnO nanostructure produced by

Successive ionic layer adsorption and reaction (SILAR) method

Irmak Karaduman1*, Tuğba Çorlu1, Memet Ali Yıldırım2, Aytunç Ateş3 and

Selim Acar1

1 Department of Physics, Science Faculty, Gazi University, Ankara, Turkey 2Department of Electric Electronics Engineering, Engineering Faculty, Erzincan University, Erzincan, Turkey 3Department of Material Engineering, Engineering and Natural Sciences Faculty, Yıldırım Beyazıt University,

Ankara, Turkey


Abstract

With the rapid development of industrialization and

urbanization in the past few decades, environment

pollution caused by the volatilization of hazardous

gases has become an important issue. Acetone, as a

widely used solvent in industry and laboratory, can

volatilize easily and affect human health when its

concentration is higher than 173 ppm [1]. Although

the study on acetone sensor is necessary, the present

reported acetone sensors have suffered from some

disadvantages, such as poor selectivity, inadequate sensitivity [2]. Therefore, it is highly desirable to

develop high performance sensors for rapidly

selective detection of acetone [3].

Among various metal oxide semiconductor (MOS)-

based gas sensing materials studied so far, ZnO,

as a nontoxic, inexpensive and wide-band-gap II-VI

compound semiconductor, has been proved to be

one of the promising materials for gas sensors [4].

It's well known that the properties of ZnO depend

highly on its nanostructures, including crystal size,

orientation and morphology. As a consequence,

ZnO nanocrystals with highly controlled

microstructures have been investigated extensively in recent years.

The traditional gas sensors using semiconductor oxides detect an objective gas in air from a

change in current caused by the adsorption and/or reaction of gases. When the sensors are exposed to air, oxygen molecules adsorbed on the surface

would be ionized to O2−, O−or O2− by capturing free

electrons from the conduction band which causes a depletion layer and a potential barrier to charge

transport is developed. The possible reactions are expressed as follows [4];

𝑂2(𝑔𝑎𝑠) + 2𝑒− → 𝑂− (1)

The acetone gas sensing mechanism of sensing

surface can be explained by

[5]:

𝐶𝐻3𝐶𝑂𝐶𝐻3(𝑔𝑎𝑠) + 8𝑂− → 3𝐶𝑂2(𝑔) + 3𝐻20 + 8𝑒− (2)

In this study, ZnO nanostructure is grown by

Successive ionic layer adsorption and reaction

(SILAR) method and investigated its acetone gas

sensing properties. The acetone sensing properties of

the ZnO nanostructure was measured at different

operating temperatures and depending on different

concentrations. Gas sensing measurements showed

the good acetone sensing performance of such

sample at low operating temperature. The sample

showed a fast response and recovery times,

excellent repeatability, and great potential for practical applications.

Figure 1 XRD pattern of ZnO nanostructure

produced by SILAR method

References [1] L.F. da Silva , A. C. Catto , W. Avansi Jr. , L. S.

Cavalcante ,V. R. Mastelaro , J. Andres , K. Aguir , E. Longo, Journal of Alloys and

Compounds 683, (2016) 186-190 [2] D. Chen, L. Ge, L. Yin, H. Shi, D. Yang, J. Yang, Sens.

Actuators B Chem. 205 (2014) 391-400 [3] A.M. Diskin, P. Spanel, D. Smith, Physiol. Meas. 24 (2003) 107–119. [4] P. P. Sahay, Journal Of Materials Science 40

(2005) 4383 – 4385 [5] W. Ping, T. Yi, H.B. Xie, F.R. Shen, Biosens.

Bioelectron. 12 (1997) 1031–1036.


Acknowledgements: This work was supported by the TUBITAK (Grant 115M658) and Gazi University

Scientific Research Fund under Project No:05/2015-09.


Esma

Daktilo Metni

Esma

Daktilo Metni


Cell Phone Microscopy + Image Processing: Low Cost Readout Method for

BioMEMS

Kutay İçöz1*

1 Department of Electrical and Electronics Engineering, Abdullah Gül University, Kayseri, Turkey


1. Introduction

According to data from World Bank approximately 7

billion cell phones are being used worldwide.

Advancements in micro fabrication technology enable

integrating various sensors in cell phones. Technical

features and extensiveness make cell phones a tool for

telemedicine.

Micro cantilevers are used to detect and measure

proteins, cells and DNA using two operation modes: resonant mode and static mode. Common techniques of

signal readout from cantilevers are measurement of

changes in laser intensity, position, or piezoresistance

(Table 1).

In this study we investigate cell phone microscopy and

image processing as an alternative readout method for

micro cantilevers. This approach has limitations

compared to conventional sensitive methods but

provides low cost, fast and mobile measurements and

can be considered as a first step analysis for micro

cantilevers.

2. Cantilevers

Micro/nano cantilevers, are mostly fabricated from

silicon, silicon oxide and silicon nitride, have been

designed and used as label-free biomolecular detectors.

Cantilever transducers convert biological signals into

mechanical deflections that can be detected using

optical, electrical and magnetic methods [1].

Table 1 Comparison of cantilever signal readout

techniques

Sensor

Type

Meas

ured

Quan

tity

Resolut

ion

Interferometry

Laser Intens

ity

0.01 Å

Optical Lever

Laser Positi

on

0.1 Å

Piezoresistive

Resistance

0.1 Å

Numerous biosensor systems based on surface

functionalized cantilevers have been implemented for

detection of various biological targets such as bacteria,

virus, proteins, DNA/RNA and cells [2], [3].

3. Cell Phone Microscopy

Low cost spherical lenses are integrated with cell

phones to develop portable microscopes [4]. These

systems can provide a resolution on the order of 1 to

10 μm. The cost of a single spherical ball lens is

less than 10 cents. 100X magnification can be

reached using a ball lens of 3.5 mm in diameter.

In this work we discuss using cell phone microscopy

+ image processing as a new readout method for cantilevers not replacing the existing ones but a

complementary low-cost, fast and portable

alternative (Figure 1). Existing measurement

methods for cantilevers provide detection of single

bacteria and virus or cell measurements such as

weighing. Cell phone microscopy can’t reach to

sensitivities for detecting viruses and can’t provide

weighing for any cell type however its current

capability is sensitive enough for detecting most of

the cell types and can be improved for bacteria.

Image processing can also provide shape and size information of each cell.

Figure 1 Left: Microcantilever imaged by optical

light microscope, Middle: Spherical Ball Lens

attached to cellphone Right: Microcantilever

imaged by the cellphone. Scale bar 100 μm.

4. References

[1] S. K. Vashist, “A Review of Microcantilevers for Sensing

Applications A Review of Microcantilevers for Sensing

Sandeep Kumar Vashist,” J. Nanotechnol. Online, pp. 1–16,

2007.

[2] K. S. Hwang, S.-M. Lee, S. K. Kim, J. H. Lee, and T. S.

Kim, “Micro- and nanocantilever devices and systems for

biomolecule detection.,” Annu. Rev. Anal. Chem. (Palo Alto.

Calif)., vol. 2, pp. 77–98, 2009.

[3] H. Etayash, K. Jiang, S. Azmi, T. Thundat, and K. Kaur,

“Real-time Detection of Breast Cancer Cells Using Peptide-

functionalized Microcantilever Arrays,” Sci. Rep., no.

August, pp. 1–13, 2015.

[4] Z. J. Smith, K. Chu, A. R. Espenson, M. Rahimzadeh, A.

Gryshuk, M. Molinaro, D. M. Dwyre, S. Lane, D.

Matthews, and S. Wachsmann-Hogiu, “Cell-phone-based

platform for biomedical device development and education

applications,” PLoS One, vol. 6, no. 3, 2011.



Thin Films of p-type Organic Semiconductors as SERS

Substrates

Mehmet Yilmaz1,2, Dilek Ozden1, Hakan Usta3 and Gokhan Demirel1*

1Bio-inspired Materials Research Laboratory (BIMREL) Department of Chemistry, Gazi University, Ankara, Turkey

2Department of Bioengineering, Sinop University, Sinop, Turkey 3Department of Materials Science and Nanotechnology Engineering, Abdullah Gül University, Kayseri, Turkey


1. Introduction

Since its discovery in 1974, surface-enhanced Raman

spectroscopy (SERS) has arisen as a powerful and

sensitive vibrational spectroscopic method providing the

detection of various molecules at ultra-low

concentrations. Numerous studies have been performed to

fabricate novel SERS platforms for different applications

covering chemistry, physics, medicine, and biology.

Despite of attempts in this research field, the present SERS platforms still have some drawbacks such as

stability and reproducibility limiting their practical

applications. Small organic semiconductors, with their

facile film deposition on flexible plastic substrates and

compatibility with low-cost and large-area

manufacturing/direct-write printing technique, exhibit

exceptional charge transport/light manipulation properties

and excellent contact formation with metals such as Au

and Ag in various optoelectronic devices. In this study, to

employ the advantages of these materials as SERS

platform, thin layer of p-type organic semiconductor (2,7-

dioctyl[1]benzothieno[3,2-b]-[1]benzothiophene,C8 BTBT) was deposited through oblique angle physical

vapor deposition (PVD) technique. The resultant organic

thin film with conformal thin layer of gold (32 nm)

exhibited remarkable SERS performances in terms of

enhancement (≈108), stability (>90 days), and

reproducibility (RSD < 0.14).


SEM images (Figure 1) depict that the film morphologies

depend on dramatically the deposition method and the

deposition angle, α. For vapor-deposition at α = 10o 2D

microstructures with highly interconnected plate-like grains are observed (Figure 1 c,d). For the case of 90o

deposition angle, high density arrays of vertically aligned

ribbon-like micro-/nanostructures, which are highly

favorable for SERS applications, were detected (Figure 1

a,b) as a result of π–π stacking interactions between the

planar benzothieno[3,2-b]-[1]benzothiophene aromatic

cores and van der Waals interactions between lipophilic

alkyl chains at the molecular termini and also variations

in film-growth mechanisms due to different deposition

thermodynamics/kinetics and shadowing effects.

SERS activity of these films was evaluated by using

methylene blue (MB) as the Raman reporter molecule (Figure 2). Due to its 3D ribbon-like micro-

/nanostructures, gold-coated C8-BTBT films fabricated at

α = 90o exhibit a remarkable increment of the SERS

signal intensities relative to that of the smooth gold film

as a result of the tip-focusing, cavity resonances and

antenna effects. Interestingly, although C8-BTBT thin-

films deposited at α = 10o does not show any obvious 3D

morphology, a dramatic enhancement in the SERS signal

is also observed, possibly due

to formation of charge transfer

mechanisms.

Figure 1 Top-view and cross-sectional SEM images of

C8-BTBT films fabricated by vapor deposition at a,b) α =

90° and vapor deposition c,d) at α = 10° [1].

Figure 2 SERS spectra of MB on Au-coated C8-BTBT

films fabricated at a) α = 90° and b) α = 10°, and of c) a

smooth gold film on silicon [1].

Two feasible routes for charge transfer may occur upon laser excitation, which are either from C8-BTBT/gold

substrate to adsorbed MB molecule or from MB molecule

to C8 BTBT/gold substrate. As shown in Figure 3, the

highest occupied molecular orbital (HOMO) and lowest

unoccupied molecular orbital (LUMO) energy levels of

C8-BTBT molecule, the work function of the gold as well

as the HOMO and LUMO energy levels of MB exhibit

proper characteristics to create charge transfer complexes

and the resultant SERS effect.

Figure 3 Schematic representations for possible charge-transfer mechanisms (a and b) between MB and the Au/C8-BTBT film [1]. References

[1] Yilmaz et al. Adv. Funct. Mater. 2015, 25, 5669–

5676.



Salmonella Detection via Silica Nanoparticle based Lateral

Flow Test Platform Müslüm Kaan Arıcı1*, Onur Bulut1,2, Oya Akça3, Meral Yücel1 and Hüseyin Avni

Öktem1,2,4

1Department of Biological Sciences, Middle East Technical University, Ankara, Turkey

2 Faculty of Agriculture and Natural Sciences, Konya Food & Agriculture University, Konya, Turkey 3 Department of Molecular Biology and Genetics, Harran University, Şanlıurfa, Turkey

4 Nanobiz NanoBioTechnological Systems R&D Limited, Ankara, Turkey


1. Introduction Target-responsive nanodevices and nanostructures

based on mesoporous silica nanoparticles (MSN) have been used for different purposes such as controlled drug

delivery, diagnostic, sensing, and biomedical imaging.

Unique features of MSNs provide advantages including

large surface area, controllable particle and pore size, and

modifiable surface over other systems.

In the present study, we report a target-responsive

oligonucleotide-capped MSN based system immobilized

on lateral flow test platform to detect Salmonella

enterica. In the presence of PCR-amplified target

sequence, the oligonucletide caps on the surface of MSNs

hybridize with the complementary target sequence which

results in opening of the pores and the release of previously loaded 3,3',5,5'-Tetramethylbenzidine

(TMB), a chromogen molecule. Released TMB

molecules are subjected to a redox reaction catalyzed by

horse radish peroxidase (HRP) with the presence of H2O2

and yield a blue colored product for detection.

2. Materials and Methods Genomic DNA isolated from pre-enriched Salmonella

enterica (typhimurium, enteritidis, and infantis)

cultures was used as template DNA. Primers

selectively amplify a 284 base-pair Salmonella specific

region were used in PCR, and the resulting amplicons

were applied as the target [1].

The external surface of TMB-loaded MCM-41

mesoporous silica nanoparticles was functionalized with

(3-Aminopropyl) triethoxysilane, then separately capped

with single-stranded oligonucleotides (Probes 1 and 2)

that are complementary to the target amplicon. Components of the lateral flow strips (sample pad,

nitrocellulose card, and backing pad) were placed on an

overlapping order. Prepared MSNs and HRP were

immobilized on the strip, 4 mm and 6 mm away from the

sample pad, respectively (Figure 1). Pre-denatured target

amplicons were mixed with H2O2, then applied to lateral

flow strips.

Figure 1 Schematic representation of a MSN-based lateral

flow strip.

3. Results and Discussion The lateral flow and MSN platform developed in this

study triggers the chromogen molecule release only in

the presence of target sequence. When the denaturated

target amplicon is applied to the sample pad, it

migrates along the strip and reaches the

oligonucleotide capped MSNs. Pore opening occurs

by a displacement reaction in the presence of a

target complementary strand. This results in

hybridization of the two oligonucleotides, the

uncapping of the pores, and release of the entrapped

TMB molecules. Released TMB is oxidized through

H2O2/HRP reaction, yielding a blue color.

Additional control experiments such as using uncomplementary target DNA, capping the MSN

surface with uncomplementary probes were also

conducted and verified the accuracy of the platform

(Figure 2).

4. Conclusions

MSN-based lateral flow test platform developed in

this study can be reckoned as rapid, accurate and

cost- effective systems that can be utilized in

laboratory and field or point- of-care environments.

References

[1] Rahn, K., et al. "Amplification of an invA gene sequence of

Salmonella typhimurium by polymerase chain reaction as

a specific method of detection of Salmonella." Molecular

and cellular probes 6.4 (1992): 271-279.

Figure 2 Visualization of MSN-

based lateral flow strips under microscope. The 284 base-pair target sequence,

uncomplementary control DNA, and only H2O2 were

applied to the strips 1, 2, and

3, respectively.




Molecularly Imprinted Polymer Based Microcantilever Sensor for the

Selective Determination of Erythromycin in Water Resources

M. Okan1*

, Esma Sari2 and M. Duman

1

1 Department of Nanotechnology and Nanomedicine, Institute of Science, Hacettepe University, Ankara,

Turkey 2Department of Chemistry, Faculty of Science, Hacettepe University, Ankara, Turkey


Abstract

Erythromycin (ERY) is a class of antibiotic that is

suggested as one of the priority drinking water

contaminants at latest European Union Water Framework Directive (EU-WFD). The main goal of this study is to

develop molecularly imprinted polymer (MIP) based

microcantilever sensor for the selective determination

ERY in water resources. ERY imprinted polymeric

nanoparticles (MIP-NPs) were synthesized with

miniemulsion polymerization and their size was measured

to be 40±10 nm with high monodispersity.

Figure 5 Schematic representation of ERY imprinted

polymeric nanoparticles.

The immobilization of MIP-NPs on the microcantilevers

was accomplished by EDC/NHS activation, which

provides monolayer covalent binding. The validation of

microcantilever sensor was performed in air for a

concentration range of 0.68- 67.94 µM, employing the

dynamic sensing mode. Binding experiments showed that decrease in frequency

was observed as the MIP-NPs were exposed to the

template molecule. Results show that air studies

performed with a cantilever that has a resonance

frequency of 150 kHz works with 96% accuracy. The

detection limit and the sensitivity of the sensor were

determined as 1 µM and 1.58 Hz/pg, respectively. The

control studies of MIP-NPs were carried out with

competing agent Spiramycin (SPI) and non-imprinted

polymeric nanoparticles (NIP-NPs). Namely, 8 fold and 3

fold lower binding affinities were observed, respectively.

Reusability studies showed that the sensor system can be

used up to 3 times. The sensor system developed is low-

cost and is easily applicable by the user. This ERY specific MIP-NPs based nanosensor has the potential to be

a pioneer in the microcantilever mass sensing via

molecular imprinting technology, as it is one of its very

first examples.

Acknowledgement: This study was supported by The

Scientific and Technological Research Council of Turkey

(TÜBITAK). Project No: 113Z222.




Fabrication and Characterization of

Miniaturized Optical Flow Cytometry Design

S. Murat1,2*, O. Bülend1,2, E. Çağlar1,2, B. Necmi1,2 and S. E. Mehmet3

1 UNAM - National Nanotechnology Research Center, Bilkent University, Ankara, Turkey

2 Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey 3 Department of Electrical and Electronics Engineering, Izmir Katip Celebi University, Izmir, Turkey


1.Introduction

Flow cytometry (FC) is used in the diagnosis and

monitoring of various diseases by inspecting, counting

and sorting the particles, cells and/or tissues which are

driven from patient. Optical flow cytometers use side

scattered light (SSC), forward scattered light (FSC) and

also fluorescence light (FL) to detect physical and chemical characteristics of flown particles. It is a

technique where cellular parameters are extracted using

a focused beam of light while they are in a fluid stream.

Examples to such parameters are cell size, granularity,

DNA content, counting of cells with specific antibody,

and protein content.

Commercial FC’s include bulk optics, which cause

alignment issues, require large amount of sample

volume and are expensive to buy and maintain.

Miniaturization of such microfluidic systems and

combining fluidic, acoustic and fiber optical components on the same glass chip is essential.

In this study, we used femtosecond laser

microfabrication which is a maskless flexible and

simple technique for concept of lab-on-a-chip

miniaturized devices and enables rapid prototyping, 3D

microstructuring into fused silica [1].

2.Experimental Details

Fabrication of miniaturized optofluidic FC microchip

starts with, CAD design and followed by the

femtosecond laser irradiation step through high precision automated XYZ stage on the one face of two

fused silica samples at very high accuracy in 3D.

Radiated samples are then immersed into HF solution in

order to develop the microchannel. Finally developed

surfaces are bonded to each other with fusion bonding

using no adhesive layer using thermal annealing for 7

hours in high temperature furnace at 650°C. The inlet

tubings are placed at last. Fabrication steps are

illustrated in figure 1.

Figure 1 Femtosecond laser fabrication steps of FC

Solidworks design and camera images of fabricated chip

can be seen in figure 2 in detail. Laser source and

optical fibers are placed through fiber slots which are at

the same size fibers so that it holds fiber tightly.

Figure 2 Fabricated FC chip, a. illustrative design,

b. camera image general, and c. closer lookup

3.Conclusion

We were able to focus 6µm polystyrene beads with 3D

hydrodynamic focusing using only one sheath fluid inlet

and one sample inlet. While focused particles passing

through laser light interrogation region, we measured FSC and SSC signals with 5 mW optical power and 405

nm wavelength of blue laser (figure 3).

In future work, we are going to add FL measurement

with fluorescence dye labeled particles and we will

improve on the signal processing capabilities with very

fast signal processing through LabVIEW FPGA.

Figure 3 FSC and SSC signals obtained by

oscilloscope.

4.References

[1] R. Osellame et al, Opt. Express 17, 8685-8695 (2009).



Biomimetic Carbon Dioxide Sequestration by Using Carbonic Anhydrase

Attached Micromotors

Murat Uygun1,2*, Virendra V. Singh1, Kevin Kaufmann1, Deniz A. Uygun1,2, Severina D. S. de Oliveira1 and

Joseph Wang1

1Department of Nanoengineering, University of California, San Diego, La Jolla, CA 92093, USA

2Department of Chemistry, Adnan Menderes University, Aydın, Turkey


1.Introduction

Carbon dioxide emissions are considered to be one of

the major contributions to climate change. Considerable

efforts aimed at mitigating the accumulations of CO2 are

currently underway. New approaches are thus being

developed to capture and sequester CO2, from effluents

and the atmosphere, including adsorption on oxides,

zeolites, metal–organic frameworks, and ionic liquids. Each of these CO2 capture processes has its own

disadvantages, such as high cost, high energy input, use

of harsh chemicals, and generation of pollutants.[1]

Storing the dissolved CO2 (as solid calcium carbonate)

is one of the most promising and environmentally

reliable methods to reduce the amount of CO2 dissolved

in water samples.[2]

Recent advances in the field of synthetic

nano/micromotors have expanded the performance,

capabilities, and functionalities of these tiny vehicles.

These developments have opened up a breadth of applications in diverse fields, ranging from energy

generation, environmental cleanup, or disease diagnosis

and treatment. For example, various detoxification

reactions and sensing protocols have been shown to be

rapidly accelerated by the autonomous motion of

catalytic micromotors and the enhanced fluid mixing

generated by such movement.[3,4]

Herein we describe a new approach based on carbonic

anhydrase (CA) functionalized micromotors for greatly

enhanced CO2 sequestration. This approach combines

the biocatalytic activity of CA with the self-propulsion of chemically powered micromotors through CO2-

saturated samples to act as highly efficient mobile

biocatalytic microscrubbers.

2.Methods

COOH-PPy:PEDOT/Pt tubular micromotors were

modified with the CA enzyme. The exposed surface

carboxyl groups were activated using 1-ethyl-3-(3-

dimethylaminopropyl)-carbodiimide / N-hydroxy

succinimide (EDC/NHS) for conjugation with CA.

The catalytic decomposition of the hydrogen peroxide

fuel at the inner Pt layer of the micromotor generates the

oxygen bubble thrust and leads to an efficient autonomous motion of the enzyme-modified

microengine. The micromotor-based rapid “on the-

move” biocatalytic hydration of CO2 to form a

bicarbonate ion, followed by the precipitation of CaCO3

in the presence of CaCl2 were described. The enzyme

CA is able to accelerate the inter conversion of CO2 to

bicarbonate, leading to significantly higher amounts of

CaCO3

3.Results

The CA modified micromotors undergo efficient

propulsion at high speeds (e.g., 106 µms-1 using 2%

peroxide), with curved, circular, and self-rotating

trajectories.

The mobile modified micromotors result in a high yield of CaCO3, corresponding to a 90% efficiency within 5

min (Fig 1.).

Figure 1 Micromotor-based CO2 sequestration and control

experiments. CO2 sequestration efficiency in the presence

of A) unmodified motor, B) modified motor with

denaturated CA, C) static CA-modified motors, D) the

static free CA; E) CA modified motors without sodium

cholate. F,G) CA-modified motors in pure water and in sea

water, respectively.

In conclusion, we have described a mobile CO2-

scrubbing platform that couples the biocatalytic activity

of CA with the autonomous movement of chemically

powered micromotors to offer highly efficient and rapid

CO2 sequestration. The self propelled CA-

functionalized micromotors are shown to accelerate the hydration of CO2 because of dramatically enhanced

fluid transport and continuous movement of CA. These

factors result in significant improvements in the CO2

sequestration efficiency and reaction time. The practical

utility of the new biomimetic micromotor approach has

been demonstrated in seawater.

4.References

[1] Ss G. Bhattacharjee, A. Kumar, T. Sakpal, R. Kumar, ACS

Sustainable Chem. Eng. 2015, 3, 1205.

[2] T. R. Karl, K. E. Trenberth, Science 2003, 302, 1719.

[3] V. V. Singh, F. Soto, K. Kaufmann, J. Wang, Angew. Chem. Int.

Ed. 2015, 54, 6896

[4] J. Wang, W. Gao, ACS Nano 2012, 6, 5745



Single-Particle Imaging for Biosensor Applications

M. Yorulmaz1*, O. Avcı2, E. Seymour1 and M. S. Ünlü2, 3

1 ASELSAN Research Center, Biotechnology Research Program Department, Ankara, 06370, Turkey

2 Department of Electrical and Computer Engineer, Boston University, Boston, Massachusetts 02215, USA

3 Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA


Abstract

Imaging of nanoparticles at the single particle level

is an important subject of recent research especially

for the applications in bio-imaging and

photovoltaics. Developing techniques in order to

image nanoparticles for early detection of diseases,

such as viral infections and cancer, as well as the use of nanoparticles for the treatment of certain types of

cancers has gained considerable attention.

ASELSAN Research Center has recently launched

research efforts in biotechnology and aims to

develop an in-vitro point-of-care biosensor that can

be used for diagnostic purposes. For this purpose, an

imaging technique that is sensitive, easy-to-

implement, low-cost, and easy-to-miniaturize is

essential. Such a technique will be useful to develop

biosensors which will transform into portable

medical imaging and detection devices, allowing for disease diagnostics in remote locations and

subsequent planning for clinical therapy.

Optical interferometric techniques have proven

utility in sensitive imaging of individual

nanoparticles in wide-field. We initially plan to

adopt the biosensor developed by Prof. Dr. Selim

Ünlü and his group. We will then study and

implement various optical schemes to improve the

sensitivity of this biosensor, targeting to detect

smaller biomolecules that would normally go

undetected with the current system.

We put efforts in creating practical, robust, and cost-effective solutions for non-laboratory environments.

Single-Particle Interference Reflectance Imaging

Sensor (SP-IRIS) has been successfully applied in

detecting synthetic nanoparticles and viruses [1]. In

spite of the strong imaging capability of the

technique, it does not require advanced optics parts.

Moreover, it can be developed using halogen light

sources instead of expensive lasers. It requires the

use of a silicon-silicon dioxide substrate as a

common-path interferometer. The schematic of the

optical setup is shown in Figure 1.

Figure 1 The schematics of SP-IRIS. (Adapted from Ref.

[2])

The interferometric detection of scattering signal

generated by the nanoparticle upon its excitation

with the light source is different than in the case of

detecting the direct scattered light, such as the

scattering signal in the dark field scattering

microscopy. The signal measured using the solely

scattering-based detection techniques scales as follows:

𝐼 ∝ |𝐸𝑠|2 (1)

where 𝐼 is the direct scattering signal and 𝐸𝑠 is

scattering field. As 𝐸𝑠 scales with 𝑟3, the direct

scattering signal scales with 𝑟6 and drops notably for nanoparticles with small sizes. For example, it

becomes very challenging to image gold

nanoparticles with sizes below 40 nm using direct

scattering signal.

On the other hand, the intensity measured using an

interferometric system is as follows:

𝐼 ∝ |𝐸𝑠 + 𝐸𝑟|2 ∝ 2|𝐸𝑠||𝐸𝑟|cos (ɵ𝑟𝑠) (2)

where 𝐸𝑟 is the reference field and the interference

signal that is the cross-term scales with 𝑟3. Therefore, interferometric methods allows for

imaging nanoparticles with smaller sizes. Using this

technique, it is possible to image dielectrics with

smaller scattering cross-sections than those of gold nanoparticles. The scattering image of 104 nm

polystyrene beads is shown in Figure 2.

Figure 2 The scattering signal of 104 nm polystyrene

beads.

Our goal is to enhance the sensitivity of this

technique through integration of polarization optics,

and achieve accurate sizing as well as shape and

orientation determination of nanoparticles in conjunction with the physical theory [3] based

forward model and various reconstruction models.

This enhancement will allow us to extend the use of

this technique for detecting a wide variety of

diseases including cancer using minute amounts of

sample.

References [1] Avci et al. Sensors, 15 (7), 17649-17665 (2015)

[2] Daaboul et al. Nano Letters, 10 (11), 4727-4731. (2010)

[3] Avci et al. Optics Express 24 (6), 6094-6114 (2016)



miRNA Sensing Self-Propelled Hybrid Micromotors

Lutfi Oksuz1, Nilgün Dükar2*, Filiz Kuralay2, Gözde Yurdabak Karaca3, Umran Koc1, Emre Uygun1 and Aysegul

Uygun Oksuz3

1Department of Physics, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey

2Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey 1Department of Chemistry, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey


Abstract

Self-propelled micromotors have enabled exciting

applications in biomedical field such as delivering

drugs, nanoscale transport and assembly [1].

Particularly, chemically powered micro/nanomotors based on different chemical compositions and structures

that are capable of moving autonomously in the

presence of hydrogen peroxide fuel. Especially,

fabrication of nano and micro propellant systems

featuring specific cell recognitions in a short time frame

is highly anticipated. Ability of micromotors for

selective capture, and isolation of cancer cells based on

the selective binding and transport ability was

demonstrated [2,3]. miRNAs are gaining recognition as

critical regulators of many biological processes,

emerging as therapeutic targets for treating disease, especially cancer cells [4].

In this study, new tungsten oxide/poly(2-fluoroaniline)

(WO3/P2FANI) based hybride was used to obtain

WO3/P2FANI/Pt micromotors which propelled

catallytically using H2O2 fuel. Biosensing properties of

the micromotors were investigated for target miRNA

sequences. Fluorescence intensity and speed of

micromotors were analyzed using NİKON Eclipse Optic

LV100ND Microscopy.

Hybride structure was obtained by using rf rotating

plasma technique. Then, hybrid powders were dispersed

in the solvent and dropped onto cleaned glass. After

drying, hybride powders coated with platinum (Pt) by rf

Magnetron Sputtering method under 6 minutes and 25

Watt power. The effects of the surfactant and the fuel

concentration onto the speed of micromotors were

investigated.

Acknowledgments: This Project is supported by

TÜBİTAK (Project No: 1150098). F. Kuralay

acknowledges Turkish Academy of Sciences (TÜBA) as

an associate member and TÜBA-GEBİP programme.

References

[1] S.S. Banerjee, A. Jalota-Badhwar, K.R. Zope, K.J.

Todkar, R.R. Mascarenhas, G.P. Chate, G.V. Khutale, A.

Bharde, M. Calderon, J.J. Khandarea, Nanoscale 7 (2015) 8684.

[2] S. Balasubramanian, D. Kagan, C.J. Hu, S.

Campuzano, M.J. Lobo-Castañon, N. Lim, D.Y. Kang,

M. Zimmerman, L. Zhang, J. Wang, Angew. Chem. Int.

Ed. 50 (2011) 4161.

[3] D. Kagan, S. Campuzano, S. Balasubramanian, F.

Kuralay, G.-U. Flechsig, J. Wang, Nano Letters 11

(2011) 2083.

[4] J. Condea, E.R. Edelmana, N. Artzia, Advanced

Drug Delivery Reviews 81 (2015) 169.



Biosensing Strategy for Detection of Bacterial Susceptibility

Against Beta Lactamases

P. Kara1*, A. N. Yurtman2, H. Taslı2, M. Limoncu2 and M. Ozsoz3

1 Ege University, Faculty of Pharmacy, Analytical Chemistry Department, 35100, Bornova- Izmir, Turkey 2 Ege University, Faculty of Pharmacy, Pharmaceutical Microbiology Department, 35100, Bornova- Izmir,

Turkey 3 Gediz University, Faculty of Engineering, Nanotechnology Department , Turkey


Introduction

An antibiotic based electrochemical biosensor for direct

detection of beta lactamase susceptibility against

cefotaxim in E. coli cell was developed in this study.

Screen printed gold electrodes (AuSPE) were used as

sensor surface and Electrochemical impedance

spectrometry (EIS) was used as transducer. Cefotaxime antibiotic was immobilized onto AuSPE’s and antibiotic

modified AuSPE surfaces were incubated with bacteria

cell culture solution including whole bacteria. Clinical

E. coli isolates that excrete extended spectrum beta

lactamase (ESBL) which were sensitive and resistant to

cefotaxime have been used for the detection.

Staphylococcus aureus and pseudomonas auroginosa

isolates were used as negative controls. A non- beta

latam antibiotic vancomycine was also used for the

detection of biosensor selectivity. β-lactamase type

enzymes are produced by some bacteria, which are mainly responsible of catalyzing the hydrolysis of β-

lactam antibiotics that causes in bacteria resistance to

these antibiotics [1]. β-lactamases catalyze the

hydrolytic degradation of the amide bond in the four

membered β-lactam ring in β-lactam antibiotics, which

inactivates the β-lactam antibiotics. Extended-spectrum

β-lactamases (ESBLs), are often the cause for resistance

to newer cephalosporins and monobactams in the

members of the family of Enterobacteriaceae. ESBLs

have been widely found worldwide [2-4]. Several

methodologies for rapid and reliable detection of beta lactamase activity were studied including, enzyme-

linked immunosorbent assay [5], spectrophotometry [6],

chemiluminescence [7] and mass spectrometry [8]

techniques. The goal of our study is to develop a

biosensor for rapid, label free, high-throughput bacterial

antibiotic susceptibility determination.

Materials&Methods

Bacteria Culture: E. coli American Type Culture

Collection (ATCC) 25922 was used as the reference

strain. The broth microdilution test was performed by

using sterile, disposable, multiwell microdilution plates

(96 U-shaped wells), and Mueller–Hinton broth (BD, France) two fold serial dilutions were prepared in

microdilution plate.

Biosensor Preparation: The illustration of the study

procedure is shown in Figure 1.

Figure 1. Schematic presenstation of the study procedure.


Figure 2. EIS datas of cefotaxim coated AuSCPE; before c) and after

incubation with b) cefotaxim sensitive, a) cefotaxim resistant E. coli

bacteria.

Conclusion

An impidimetric cefotaxim cytosensor for direct

detection of beta lactamse activity and resistant in E.

coli strains was developed. The selectivity of biosensor

was evaluated by using non- beta latam antibiotic

vancomycine and Staphylococcus aureus and

pseudomonas auroginosa isolates. It was shown that the

designed biosensor is capable of label free; low-cost,

fast and reliable detection. Furthermore system can be

applied to produce susceptibility test kits.

References [1] Z. Xu, H.Y. Wang, S.X. Huang, Y. L. Wei, S.J. Yao, Y.L. Guo,

Anal. Chem., 82, (2010), 2113 -2118.

[2] P.A. Bradford, Clin. Microbiol. Rev., 14, (2001), 933-951.

[3] B.S. Kocazeybek, Chemother., 47, (2001), 396-408.

A.M.Hujer, K.S. A.M., Keslar, N.J. ,K.S. Dietenberger, C.R. ,N.J.

Bethel, A. Endimiani, R.A. Bonomo, Detection of SHV beta-

lactamases in Gram-negative bacilli using fluorescein-labeled

antibodies, BMCMicrobiol, 2009, 9, 46 -49.

[4] Z.Y.K. Naomi, Simple Photometric Assay of f-Lactamase Activity,

Antimicrobial Agents and Chemotherapy, 1972, 2, 356 -359

[5] P. Liang, R.I. Sanchez, M.T. Martin, Electrochemiluminescence

based detection of beta lactam antibiotics and beta lactamases, Anal.

Chem., 1996, 68, 2426 -2431.

[6] M.T. Cancilla, M.D. Leavell, J. Chow, J.A. Leary, Mass

spectrometry and immobilized enzymes for the screening of inhibitor

libraries, Proc.Natl.Acad.Sci. 2000, 97(22), 12008–12013.

[7] J.M. Park, J.I. Kim, H.W. Song, J.Y. Noh, M.J. Kang, J.C. Pyun,

Biosensors & Bioelectronics, 2015, 71, 306 -31



Functional GQDs nano-composite fabricated for direct and rapid detection of

BPA with paper based fluorescent system

Recep Üzek1,2*, Esma Sari1,2, Serap Şenel1, Arben Merkoçi2

1 Department of Chemistry, Hacettepe University, 2 Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and

Technology


Abstract

In this study, we developed fluorescent sensor for the

sensitive and selective detection of BPA. NPs were

prepared by mini-emulsion polymerization and GQDs

were prepared by hydrothermal pyrolysis. GQDs were

attached to the NPs by EDC/NHS coupling. Fluorescent

nanosensor was characterized by using Zetasizer,

UV−vis and photoluminescence spectra, TEM and FTIR.

The nanosensor gave response to BPA as an

enhancement in the PL intensities. The detection limit

(LoD) and selectivity using the fluorescent nanosensor was found to be comparable to the other techniques. For

example, the LoD of SERS of core-shell Au

nanoparticles was demonstrated to be 0.53 µM and

competed with other methods such as

chemiluminescence, direct irradiation and UV-vis

methods which usually detect BPA with 0.1 nM LoD.

In summary, we have reported several significant novelty

as follows. First, the paper-based sensing system, hıgh

selectivity of MIP and fluorescence property of GQDs

were successfully combined to provide selective,

sensitive, rapid and inexpensive sensing strategy for BPA

monitoring. Besides, we have reported a sensing

platform than can be exploited with small volumes of

nano composite and BPA solution. In this respect, this

material could be easily produced for application in

fields of research and industrial because it is easy to

synthesize, cheap, non-toxic and environmentally friendly. In addition, sensing system can be easily

extended to the monitoring not only for pollutants but

also for bıomolecule by simply choosing different

functional monomer for the molecular imprinting

techniques.



Detection of Micro and Nanoparticles in a Microfluidic Device Using Resistive

Pulse Sensing Technique

S. Resul1*, E. Caglar2,3 and D. Memed4

1 Department of Mechanical Engineering, University of Siirt,

2 UNAM - National Nanotechnology Research Center, Bilkent University, Ankara, Turkey 3Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey

4 Department of Bioengineering, University of Hacettepe


1.Introduction

Resistive pulse sensing (RPS) technique, in 1996, has

been initially introduced for single-stranded RNA and

DNA molecules detection using a biological α-

hemolysin pore [1]. Then, the technique has been

employed for high-throughput detection of micro and

nanoparticles. Since, nanoparticles are used in many

application domains such as cosmetics, photovoltaics

and medicine [2]. On the other hand, dynamic light

scattering (DLS) method is commercially used to obtain

diameter and size distribution of the nanoparticles in suspension. However, accuracy of this technique is

relatively low compare to RPS technique [2] because,

while RPS detects and counts nanoparticles

individually, DLS measures scattered light with

fluctuations caused by Brownian Motion, which is not

observable if particle diameter is greater than 10 µm.

Here, we present the RPS technique to detect and count

micro particles individually as a consequence of

blocking ionic electrical current. We also synthesised

silica nanoparticles using tetraethylorthosilicate (TEOS)

method and counted them using DLS and compared the

results with those obtained from SEM.

2.Fabrication Method

Two photo-definable epoxy SU-8 thicknesses were

coated on silicon wafer and then patterned using

standard lithography. Obtained depth of the whole

microfluidic structure is 35 µm, and wide of

microconstriction (MR) is 20 µm. Polydimethylsiloxane

(PDMS) resin and curing agent are mixed well at ratio

of 10:1 and degassed for 1 hour and then poured to top

of fabricated mold. Microfluidic channel is bonded onto

a glass where gold readout electrodes are coated using e-beam evaporation. Figure 1 shows schematic image of

microfluidic channel and microconstriction image of

fabricated microfluidic device under microscope.

Figure 1 a) Schematic image of microfluidic channel

b) Microconstriction image of fabricated microfluidic

device under microscope (scale bar- 100 µm)

3.Results

Figure 2 demonstrates DLS measurement results of the

particles including size distribution and diameter of, and

presents a mean value. According to results, mean

diameter of the particles is found to be 468.9 nm.

However, when the diameter of the particles is

measured using SEM, it is found to be approximately

360 nm. Since DLS presents a mean value for particle

diameter. As it can be seen in Figure 3 while some of

the particles are agglutinated, others not.

Figure 2 DLS measurement results

Figure 3 SEM image of silica nanoparticles

4.Conclusion and Discussion

In this study, we show that DLS method is not always a

proper way to determine size distribution and diameter

of the particles when the results obtained from DLS are compared with those obtained from SEM or RPS

technique. RPS technique enables very reliable way for

particle detection since the technique measures the

particles individually.

5.References

[1] Kasianowicz, John J., et al. Proceedings of the National Academy

of Sciences (1996): 13770-13773.

[2] Fraikin, Jean-Luc., et al.."Nature nanotechnology 6.5 (2011): 308-

313.



Synthesis of Functionalized Fluorescent Carbon Nanoparticles as Artificial

Enzymes and Signaling Tools for Their Use in Bioanalysis

G. Rükan1,2, *, A.Ö. Melis1, B. Burcu1 and B. Dilek2,3

1 Functional Nanomaterials Lab, Chemical Engineering Dept., Mersin University,

Çiftlikköy Kampüsü 33343, Mersin, Turkey 2 Mersin University Advanced Technology Education, Research and Application Center (MEITAM),

Mersin University, 3Mersin University Faculty of Pharmacy Department Of Pharmaceutical Toxicology


1.Introduction

Fluorescent nanoparticle-based biolabels are promising

tools which could give pave the way to develop new

medical diagnostic tools based on their advanced optical

properties with extreme resistance to photobleaching

compared to conventional molecular probes. Although,

significant progress has been made in nanoparticle-

based biological labelling and imaging, the concern

about the possible toxicity of these materials at

functional concentrations has severely limited their

widespread use in clinic [1,2]. Carbon dots are new member of carbon based

nanostructures. They can be synthesized from several

carbon sources and at nanosize show auto-fluorescence.

This materials with low photo-bleaching, low

cytotoxicity, biocompatibility are of great interest due to

their potential in many fields requiring non hazardous

materials.(4) Here, we report fluorescent carbon

nanoparticle-based nanolabels which could be suitable

for bio-imaging, diagnostics as fluorescent nanolabel as

well as due to surface functional moeities, they function

as enyzme mimitics for oxidation reactions. To do so,

we used different carbon sources including molasses and some industrial co-products as carbon source and

mixed them with different pigments, metals and so on to

obtain various carbon nanodots with so many different

properties. Synthesized fluorescent carbon nanoparticles

were further conducted to bioassays for the analysis of

several medically important molecules such as

Hydrogen Peroxide, Dopamine and Mercury.

2.Materials and Methods

Synthesis of FCNPs The synthesis of FCNPs was accomplished according to

the method described previously by Mukherjee [3]. A

homogeneous suspension of carbon source was obtained

without aggregation by vigorous mixing.. The mixture

was maintained at 250°C for 45 minutes until a dark,

caramelized, semi-solid texture was obtained. The

resulting material was dissolved in 2 mL of MilliQ-

water (Millipore Inc., Ω = 18 MΩ·cm). The suspension

was centrifuged at 5.000 rpm for 30 minutes; the final product was vacuum-dried. The synthesis of the carbon

nanoparticles were monitored by irradiating with a 365

nm UV light source. Further characterizations of the

synthesized CNPs were performed as described above.

Characterization of fluorescent CNPs

Ultraviolet-visible (UV-Vis) spectra of CNPs were

recorded using an Shimadzu UV-1800 UV-VIS

spectrophotometer ). X-ray diffraction (XRD) analyses

were performed in a Rigaku Smartlab Intelligent X-ray

diffractometer (XRD). Fourier transform infrared

(FTIR) spectroscopy was performed in a range of 400–

4.000 cm−1. Transmission electron microscopy (TEM;

JEOL) was used to determine the size and morphology

of the dispersed FCNPs. Fluorescence spectra of particle

solutions were measured using a Varian Cary Eclipse Fluorescence Spectrophotometer.

Figure 1. True colour photographs of fluorescence

emission from synthesized carbon nanodots (Ext./400nm). Core image has been taken from Ref [4].

Analysis Presence of dopamine and Mercury from liquid

ssamples was measured by evaluating the changes in the

fluorescence response of different carbon nanoparticles

while H2O2 analysis was carried out by measuring the

color change of ABTS following a standard peroxides

test.

Acknowledgements. This study is partially funded by

Mersin University Scientific Research Project Unit

(Project No: 2016-AP4-1791)

3.References

(1) Liu, Q.; Chen, M.; Sun, Y.; Chen, G.; Yang, T.; Gao, Y.; Zhang,

X.; Li, F.. Biomaterials 2011, 32 (32), 8243–8253.

(2) Schütz, M.; Steinigeweg, D.; Salehi, M.; Kömpe, K.; Schlücker,

S. Chem. Commun. 2011, 47 (14), 4216–4218.

(3) Mukherjee, P.; Misra, S. K.; Gryka, M. C.; Chang, H.-H.; Tiwari,

S.; Wilson, W. L.; Scott, J. W.; Bhargava, R.; Pan, D. Small 2015,

11 (36), 4691–4703.

(4) Demchenko, A. P.; Dekaliuk, M. O. Appl. Fluoresc. 2013, 1 (4),

042001.



Preparation of Polypyrrole based electrodes for Glucose 6-phosphate

determination

S. Sahin1*, I. Ozmen1, G. Yıldırım2 and S. Percin Ozkorucuklu2

1 Department of Chemistry, Suleyman Demirel University,

2 Department of Molecular Biology and Genetics, Istanbul University,


Introduction

The determination of the glucose 6-phosphate (G6P) in

blood or human tissue informs about many diseases

associated with glucose 6-phosphate dehydrogenase

(G6PD) deficiency [1]. Therefore, there are several

studies on improving of biosensor for glucose-6-

phosphate measurement. To date, developed biosensors

have based on combinations of G6PD and different mediators or enzymes [2].

The aim of this study was to prepare G6P biosensors

which contain polypyrrole (PPy) and Fe3O4-Chitosan

(CS) nanoparticles and optimize several parameters for

maximum response.

Methods

Ppy and Fe3O4-CS-PPy electrodes were prepared

electrochemically onto pencil graphite electrode.

Electrochemical synthesis was performed with pyrrole

in acidic solution at constant current density of 0.35 mA

cm-2. Surface morphology of electrodes was determined with SEM analysis. Then, glucose 6-phosphate

dehydrogenase (G6PD) was immobilized on electrodes

via glutaraldehyde. Optimum enzyme immobilization

conditions were determined for two electrodes.

Chronopotentiometric curves of electrodes were

recorded at current density of 0.25 mA cm-2 for different

G6P concentrations. Various optimization studies, such

as pH, enzyme concentration, and NADP+

concentration, were performed to obtain maximum

responses for G6P measurement. To determine the

usefulness of the prepared G6P biosensor, human blood serum samples were spiked with known concentrations

of G6P and were used as analytes for the measurements.

Results

As a result, Ppy and Fe3O4-CS-PPy electrode showed a

broad lineer response to G6P in the range of 0,025 to

0.25 mM and 0.005 to 0.1 mM, respectively. The results

of optimization studies are given in Table 1. Surface

morphology of Fe3O4-CS-Ppy and PPy electrode is

shown in Figure 1.

Table 1 Optimization results

Paramet

ers PPy

Fe3O4-CS-

PPy

pH 8.5 8

Enzyme

concentration 2 U 1 U

NADP+ 1.25 mM 1.25 mM

concentration

Figure 1 SEM images of naked pencil graphite

electrode (a) and electrochemically prepared PPy (b)

and Fe3O4-CS-PPy (c) electrodes onto pencil graphite

References

[1] S. Banerjee, P. Sarkar, A. P. F. Turner,

Amperometric biosensor based on Prussian Blue

nanoparticle-modified screen-printed electrode for

estimation of glucose-6-phosphate. Anal. Biochem.

439(2013) 194–200. [2] Y. Cui, J. P. Barford, R. Renneberg, Development

of a glucose-6-phosphate biosensor based on

coimmobilized p-hydroxybenzoate hydroxylase and

glucose-6-phosphate dehydrogenase. Biosens.

Bioelectron, 22(2007) 2754–2758.



Detection of Alzheimer`s Protein on Polycarbonate Nanopillared Films by Using

Surface Enhanced Raman Spectroscopy

Sevde Altuntas1*, Can Simon Pervane2 and Fatih Buyukserin3

1Biomedical Engineering Graduate Program, TOBB Univ. of Econ. & Technology, Ankara 06560, Turkey

2Institute of Complex Systems Simulation, University of Southampton, Southampton SO171BJ, United Kingdom 3Department of Biomedical Engineering, TOBB Univ. of Econ.& Technology, Ankara 06560, Turkey


Introduction Alzheimer`s disease is responsible for neuronal damage

of cerebral cortex and hippocampus because of Amyloid

β 1-42 protein accumulation. The protein detection

studies have gathered around ELISA assay and PCR

assays which are expensive, require specialized

personnel and can contain complex protocols. On the

other hand, Surface-enhanced Raman Spectroscopy (SERS) can potentially allow even single molecule

detection in solutions or solid surfaces. In addition,

SERS signal from a target molecule can be further

increased by using nanopatterned surfaces when

compared to smooth counterparts. Moreover, Raman

signals are specific to molecules, so one can comment

about content of a sample. For this reason we focused

Alzheimer protein detection on nanopatterned polymer

surface by using SERS techniques.

Materials&Methods

Nanoporous anodic aluminum oxide membrane (AAM) was synthesized by using two step anodization method

from high purity aluminum. According to electrolyte

type, anodization time, voltage values and temperature,

AAM thickness, column structure or pore size were

arranged. The nanoporous film was coated with n-

octadecyltrichlorosilane to decrease its surface energy.

AAM was coated polycarbonate (PC) solution (wt/v

6%) by using drop-casting method. After solvent

evaporation, the PC film was removed from the surface.

The nanopatterned surface was coated with gold

(thickness: 10, 20 and 30 nm) by using thermal

evaporator (Nanovak, NVTS 400). After gold coating process, the polymer films were decorated with different

concentrations of Thioflavin – T which is widely used

to visualize and quantify the presence of misfolded

protein aggregates called amyloid. SERS technique was

used for protein and Thioflavin – T detection (DeltaNu

Examiner Raman microscope. Laramie, WY).

According to decrease of Thioflavin – T signal, amount

of the amyloid protein were determined. Limit of

detection was found 0.5 pg/ ml for the protein.

Results

In this context, our study proposes to fabricate diagnostic test models that utilize Au-coated

nanopatterned PC surfaces modified with Thioflavin - T

to detect low concentrations of Amyloid-β 1-42 protein

in water and artificial saliva medium by the

enhancement of protein SERS signal. Nano patterned

PC surface was fabricated by using nanoporous AAM as

a mold. To AAM column structure, three different types of PC arrays were fabricated to enhance SERS signals.

The PC films were then decorated with Au and

Thioflavin – T for detection Amyloid-β 1-42 protein.

(Figure 1). The protein detection studies were conducted

in water and artificial human saliva. SEM, SERS, FTIR,

fluorescence microscopy and contact angle

measurements were carried out for the characterization

of different surfaces and further demonstration of the

protein attachment. In addition to experimental study,

computational enhancement studies were carried out by

using COMSOL Multiphysics.

The results will be presented comparatively.

Figure 1 SEM images of nanopatterned surface (a), and branched nanopatterned surface (b). SERS spectrum of Thioflavin – T modified nanopatterned and flat PC surface (c).

Conclusion To conclude, SERS intensity of multibranched

nanopatterned surface is much higher than other

samples because of the high hot spot probability.

Besides SERS results of 20 nm gold coating and 10-5 M

Thioflavin – T decoration are more favorable to

measure amyloid amount. In addition to all of them, the

COMSOL results will be shared during presentation.

Acknowledgment: This work was supported by The


Turkey (TUBITAK) Grant No: 214Z167.



Smart Surface Based Guiding of Microdroplets Over Laser Ablated

Sinusoidal Rail

Z. Rashida, Y. Morova

b, B. Yalızay

b, U. C. Çoşkun

c, A. Erten

a, A. Jonas

b and A. Kiraz

a,d*

a Koç University, Department of Physics, Sariyer, Istanbul b Istanbul Technical University, Department of Physics, Maslak, Istanbul

c Istanbul Technical University, Department of Mechanical Engineering, Maslak, Istanbul d Koç University, Department of Electrical and Electronics Engineering, Sariyer, Istanbul


Abstract

Droplet-based microfluidic systems have been shown to

be compatible with many chemical and biological

reagents and capable of performing a variety of ‘‘digital

fluidic’’ operations that can be rendered, programmed

and reconfigured. This platform has dimensional scaling

benefits that have enabled controlled and rapid mixing

of fluids in the droplet reactors, resulting in decreased reaction times. This, coupled with the precise generation

and repeatability of droplet operations, has made the

droplet-based microfluidic system a potential high

throughput platform for biomedical research and

applications.

We present a method of water droplet generation using

oil as a host liquid using T-junction geometry and

guiding of those droplets on hydrophilic glass slide rail

surrounded by hydrophobic PDMS surface. The

trajectory of different sizes of the droplets is determined

using cross correlation algorithms for different depths of

the track over the coated cover glass slide. The

coordinates of the track, on the other hand, are evaluated by scanning the whole image along the two

dimensions and detecting the color transition while

moving from left to right along the rail. The distance

between the centers of droplet path and track is

calculated for several droplets and presented in the form

of histograms to find the quality of guiding for three

different specimen.



Dielectrophoretic Spectra of Polymorphonuclear White Blood Cells

Z. Çağlayan1*, Y. Demircan Yalçın1, 3, G. Özkayar2, 3, E. Özgür3 and H. Külah1, 3, 4

1 Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara, Turkey

2 Department of Biomedical Engineering, Middle East Technical University, Ankara, Turkey 3 Mikro Biyosistemler Inc.

4 METU-MEMS Research and Application Center


1.Introduction

Dielectrophoresis (DEP), is a sensitive and rapid

method, utilized for separation of dielectrically different

cells, even with similar sizes in a label-free manner. For

cell separation through DEP, dielectric properties of the cells should be known. In this study, dielectrophoretic

spectra of polymorphonuclear white blood cells (WBCs)

were investigated.

2.Theory and Design

Dielectrophoresis is described as the relative movement

of particles and suspending medium in nonuniform

electric field. Time averaged DEP force for spherical

particles is:

𝐹𝐷𝐸𝑃 = 2𝜋𝜀𝑚𝑟3𝑅𝑒(𝑓𝐶𝑀)𝛻|𝐸2| (1)

where r is the radius of the cell, 𝛻|𝐸2| is the gradient of

the external electric field magnitude square, 𝜀𝑚 is the

permittivity of the medium and 𝑅𝑒(𝑓𝐶𝑀) is the real part

of the Clausius-Mossotti factor. According to 𝑓𝐶𝑀,

particles can be either pulled towards stronger electric

field region (positive DEP-pDEP) or pushed towards

weaker electric field region (negative DEP-nDEP) [1].

A DEP spectrum device, with reciprocal V-shaped

planar-electrodes was utilized to obtain DEP spectra of

polymorphonuclear WBCs by using pDEP effect. The

gap between electrode tips is 20μm. The angle between

arms of electrodes is 30˚. A parylene chamber

(h=20μm) was constructed to create reservoir for cell

solution. The schematic and the fabricated views of this

device can be seen from Figure 1.

Figure 1 Schematic view (a) and the fabricated

view (b) of DEP spectrum device

3.Results and Discussion

For each test, 4µl cell suspension was put into the

reservoir and waited until solution motion stopped. 10Vpp at 15 different frequencies (100 kHz-50 MHz)

was applied and the motion of cells was recorded

with a CCD camera (SONY/DXC-107AP). Velocity

of cells was determined through Meazure and

VirtualDub. When velocity of the solution is zero,

velocity of cells can be directly related to

Re(𝑓𝐶𝑀) 𝛻|𝐸2|, keeping 𝛻|𝐸2| as same for each cell. WBCs can be examined in two main groups as

polymorphonuclear WBCs (neutrophils and

eosinophils) and mononuclear WBCs (lymphocytes,

monocytes and basophils). The first three most

abundant WBC types are neutrophils, lymphocytes

and monocytes in the order, forming the largest

portion of total WBCs in blood [2]. Therefore, to get

knowledge about DEP spectra of WBCs, it is

decided to start with polymorphonuclear WBCs.

For tests, whole blood is taken from healthy woman

donors. After treating the blood with Ficoll,

developed OptiPrep procedure is applied to get polymorphonuclear and mononuclear WBCs

separately. The procedure is based on the formation

of density gradient. The obtained velocity vs.

frequency profiles for two donors with standard

deviations can be seen from Figure 2.

Figure 2 Velocity vs frequency profile of

polymorhonuclear WBCs of two healthy donors

As a future work, remaining dielectrophoretic

spectra of mononuclear WBCs, will be examined

and compared with polymorphonuclear WBCs. With

this way, DEP spectra of WBCs will be obtained.

4.References

[1] Y. Demircan, A. Koyuncuoğlu, M. Erdem, E. Özgür, U. Gündüz,

and H. Külah. “Detection of Imatinib and Doxorubicin

Resistance in K562 Leukemia Cells by 3D-Electrode

Contactless Dielectrophoresis,” Transducers, 2013, pp. 2086-

2089

[2] White Blood Cell Count (WBC) and Differential.” Internet:

http://www.rnceus.com/cbc/cbcwbc.html, 2013 [10.11.2015].

0

5

10

15

20

25

30

35

40

45

4,5 5,5 6,5 7,5 8,5

velo

city

(µ

m/s

ec)

frequency (10^x)

donor 1 donor 2



Point-of-Care Measurement of Erythrocyte Sedimentation Rate

Z. Işıksaçan1* and Çağlar Elbüken1

1 Institute of Materials Science and Nanotechnology, National Nanotechnology Research Center, Bilkent

University, Ankara, Turkey


Introduction

Erythrocyte aggregation (EA) is a process where erythrocytes form face-to-face structures at stasis or low

shear rates. Erythrocyte sedimentation rate (ESR) is a 1-

hour clinical test for inflammation screening [1]. Here,

we report a point-of-care device that measures ESR

from EA using 40 µl fingerstick blood in 1.5 minutes

with a novel measurement method.

Methods

The measurement system consists of a disposable

cartridge and a portable opto-electro-mechanical

analyzer. The cartridge channel is illuminated with an

infrared light. A constant pressure is applied to the

channel for complete disaggregation. As the

erythrocytes aggregate, the transmitted light intensity

from the erythrocytes in the channel is recorded for 1.5

min. The intensity level is lowest at complete

disaggregation and highest at complete aggregation.

From this data, ESR is measured.


For experimental verification of the measurement

method, first, we added dextran polyglucose, an

aggregation inducer, of different concentrations in blood

samples obtained from a healthy male volunteer. We

measured the ESR of the samples using our system and

the conventional 1-hour test. We showed that the

amplitude of the transmitted signal is in correlation with

the conventional test result with R2 of 0.98 using linear

regression.

Secondly, we used blood samples from three patients.

The ESR values were measured using our system and the standard Westergren method. We showed that the

correlation between the two methods is very good with

R2 of 0.99 using linear regression.

Conclusion

This work demonstrates that our point-of-care reliably

measures ESR from EA. To the best of our knowledge,

this is the most rapid ESR measurement method

provided in the literature. The measurement takes only

1.5 minutes (in comparison to 1 hour in the

conventional test) and uses only 40 µl whole blood (as

opposed to 2 ml blood used in the conventional test).

When a high speed camera is integrated onto the cartridge, we can also monitor EA process to better

understand the mechanism of this physiological

phenomenon.

Figure 1: Standard ESR versus microfluidic ESR test

results using different dextran concentrations

Figure 2: Standard ESR versus microfluidic ESR test

results using blood samples from different patients

Acknowledgement

The authors acknowledge support from The Scientific

and Technological Research Council of Turkey

(TUBITAK project no. 213S127).

References

[1] “Red Blood Cell Aggregation,” O. Baskurt, B. Neu,

H.J. Meiselman, CRC Press (2011).


Poster

Presentations


Highly monodispersed droplet generation using a microfluidic system

Ali Kalantarifard1,2* and Çaglar Elbuken1,2

1 UNAM - National Nanotechnology Research Center, Bilkent University, Ankara, Turkey

2 Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey


1. Introduction

During the last decade droplet generation has become a

significant field of research because of its wide

applications in science and microscale engineering. The

ability to generate highly monodispersed microdroplets

has applications in various fields such as chemical,

biological and medical study [1]. One of the needs to

achieve monodisperse droplets is having stable and

uniform flow rate of the fluids which are supplied by

the pumps [2]. There are mainly two types of pumps

used for making droplets: pressure-driven pump and

syringe pump (Figure 1). By using pressure-driven

pump, two immiscible fluids can be supplied to the inlets of the chip by pressurized air. For syringe pump,

fluids are supplied to microchannel by pushing the

plunger by the gear motor [3]. In this study, the

performance of these two pumps is compared for

generating monodisperse droplets. The same number

and size of droplets are investigated numerically and

experimentally to compare the results in terms of

monodispersity.

Figure 1 Schematic of syringe pump and pressure

pump systems

2. Experimental Setup

Experimentally droplet generation is performed by

using syringe pump and pressure pump. For both

experiments, the two immiscible fluids are silicone oil

(carrier fluid) and deionized water (dispersed phase).

The PDMS microchannel is fabricated using soft

lithography and then bonded on the glass slide.

Numerical Simulation

The same geometry as the fabricated device was

simulated numerically. In order to find the flow field and solving the equations Comsol 5 with laminar two-

phase flow level-set method was used. In addition, flow

rate and pressure were controlled as initial condition to

attain the same size of droplet obtained in the

experiments. Then, monodispersity of the droplets was

analysed by calculating area of each droplet and

comparing with experimental results [4].


Figures 2 and 3 show the results of droplet area

distribution in numerical and experimental model

respectively. Moreover, as it is shown in Table 1,

coefficient of variation of droplets area for syringe

pump case is higher than the pressure pump case in both

models.

Figure 2 Droplet area in numerical model

Figure 3 Droplet area in experimental model

Table 1 Coefficient of Variation of droplet area

Experimental Numerical

Pump Syringe

pump

Pressure

pump

Syringe

pump

Pressure

pump

CV% 1.5 3.87 0.63 1.28

4. Conclusion

The numerical and experimental results show that by

using syringe pump we can obtain more monodispersed

droplets. Also, according to results in both cases, CV

for experimental method is higher than numerical, due

to the fluctuation of flow rate and pressure induced at

the experimental setup.

References

[1] Teh S, Lin R, Hung L, Lee A P, 2008 Lab Chip 8 198. [2] Zeng W, Jacobi I, Li S, Stone H, 2015 Journal of Micromechanics and

Microengineering 25 115015.

[3] Korczyk P M, Cybulski O, Makulskaa S and Garstecki P 2011 Lab Chip 11 173.

[4] Basu A S 2013 Lab Chip 13 1892.

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Graphene/Pt nanoparticles/nafion nanocomposite as a novel electrochemical

sensor for voltammetric determination of aliskiren

A.K. Ates1*, E. Er

1 and N. Erk

1

1 Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara-Turkey


1. Introduction

The renin-angiotensin-aldosterone system (RAAS) has

long been recognized to play a significant role in

hypertension pathophysiology. Certain agents that

modify the RAAS can control blood pressure and

improve cardiovascular outcomes. Aliskiren (ALS) is

the first of a new class of antihypertensive agents

known as renin inhibitors. Renin inhibitors are antihypertensive drugs that block the first step in the

renin-angiotensin system. Their mechanism of action

differs from that of the angiotensin-converting enzyme

inhibitors and angiotensin-receptor antagonists, but like

these drugs, renin inhibitors interrupt the negative

feedback effects of angiotensin II on renin secretion [1-

2]. The determination of ALS at low-level has a great

importance especially in real samples. Herein, we

presented a facile and effective electrochemical

nanosensor based on graphene/platinum

nanoparticles/nafion (GRP/PtNPs/NFN) for the electrochemical sensing of ALS using adsorptive

stripping differential pulse voltammetry (AdsDPV).

2. Experimental

Graphene/platinum nanoparticles (GRP/PtNPs)

nanocomposite was produced from graphene oxide

(GO) via one-step chemical reduction method [3-4]. For

the fabrication of proposed sensor, GRP/PtNPs solution containing NFN (0.25%, v/v) was prepared to constitute

the GRP/PtNPs/NFN nanocomposite. A certain amount

of dispersed GRP/PtNPs/NFN solution was dropped

onto a clean GCE surface to obtain the proposed

modified electrode (GRE/PtNPs/NFN/GCE).

The electrochemical performance of ALS on

GRP/PtNPs/NFN/GCE was investigated in detail by cyclic voltammetry (CV) and AdsDPV. An irreversible

and well-defined oxidation peak approximately at 1100

mV was observed on GRP/PtNPs/NFN/GCE using

AdsDPV. Under optimal conditions,

GRP/PtNPs/NFN/GCE exhibits good sensitivity and

selectivity in the detection of ALS. The linear

concentration range for ALS was found to be 0.1-5.0

µM with a low detection limit.

3. Conclusion

It is the first time that a novel and highly sensitive

graphene-based electrochemical platform was

designed for the sensing of ALS. For this purpose,

GRP/PtNPs/NFN nanocomposite has been

fabricated as an electrochemical sensing

material. GRP/PtNPs/NFN/GCE sensor exhibited

an outstanding analytical performance towards the

ALS due to its unique physical and chemical

properties of graphene and platinum nanoparticles.

The developed method was successfully applied to the determination of ALS in human plasma with

satisfactory recovery results. It is concluded that

GRP/PtNPs/NFN/GCE could be promising

alternative sensor for routine analysis of ALS in

real samples.

References

P. Wal, A. Wal, A. Kai. R, A. Dixit, J Pharm

Bioallied Sci. 2011 Apr-Jun; 3(2): 189–193.

J.W. Cheng, Clinical Therapeutics, 2008

Jan;30(1):31-47.

W.S. Hummers, R.E. Offeman, J. Am. Chem. Soc. 80 (1958) 1339.

T.Q. Xu, Q.L. Zhang, J.N. Zheng, et al.,

Electrochim. Acta 115(2014) 109–115.




Graphene based hydrogen peroxide sensitive biosensor for glucose sensing

A.Öncül1*, S.Cete2 and A.Yasar2

1Institue of Natural Sciences, Gazi University, Ankara, Turkey 2 Department of Chemistry, Gazi University, Ankara, Turkey


1. Introduction

Graphene is a carbon allotrope formed with sp2

hybridized carbon atoms arranged in a 2-dimensional

structure. [1] Its physical properties, such as excellent

carrier mobility (200.000 cm2V-1s-1 for single layer) [2] and very large surface area (2630 m2g-1) [3] make it a

very popular choice for various applications.

Biosensors including glucose biosensors are becoming

increasingly important due to their applications in

biological and chemical analyses, clinical detection, and

environmental monitoring. We design a sensitive

electrochemical sensor for glucose based on a glassy

carbon electrode that was modified with a

nanocomposite containing graphene, platinum

nanoparticles (Pt-NPs) and nafion. The significance of

glucose in human metabolism is well known, as is the fact that the defects in glucose level lead to

complications of diabetes. [4]


High-quality graphene (GR) was produced by an

effective chemical method using Hummers' method. [5]

GR/NFN(Nafion) preparation, the NFN solution was

added to obtain 0.25 (m/v) nafion concentration in the

GR solution. The quantification of glucose can be

achieved via electrochemical detection of the

enzymatically unchained H2O2. The immobilization of

glucose oxidase (GOD) over Nafion-solubilized metal

nanoparticles dispersed graphene and electrode has been

achieved by cross-linking with glutaraldehyde. The performances of the biosensor have been investigated

by electrochemical method at an optimum potential of

+0.6V in pH 7.0 phosphate buffer. All the

electrochemical measurements were performed with a

conventional three-electrode system.

3. Conclusions

There are many reports regarding the electro catalytic

activity of gold and platinum for the sensing

applications of glucose. [6]

In our study glucose biosensor based on immobilization

of GOD in Pt nanoparticles/graphene/NFN

nanocomposite film is responsive to a low concentration

of H2O2 (~5µM) and two different linear determination

ranges of 10-5-10-4 M (shown in figure-1) and 10-3-10-1

M are detected.

According to literature values [7-10] our sensor has low

detection limit and long linear range among to other

studies. This properties shows us our sensor is good

candidates for biochemical applications.

Figure 1 Concentration vs. Current between

10-5-10-4 M H2O2 +0.6V in pH 7.0 phosphate buffer

4. References

[1] A. K. Geim and K. S. Novoselov, Nat. Mater., 2007, 6, 183–191. [2] K. I. Bolotin, K. J. Sikes, Z. Jiang, M. Klima, G. Fudenberg,J. Hone, et al., Solid State Commun., 2008, 146, 351–355. [3] Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts and R. S. Ruoff, Adv. Mater., 2010, 22, 3906–3924. [4] Shankaran DR, Uehara N, Kato T. 2008. Biosensors and

Bioelectronics 18:721–728. [5] W.S.Hummers, R.E.Offeman, J.am.Chem.Soc.80 (1958) 1339 [6] R.B. Rakhi, K. Sethupathi, S. Ramaprabhu, J. Phys. Chem. B 113 (2009) 3190–3194. [7] R. Ning, W.B. Lua, Y.W. Zhang, X.Y. Qin, Y.L. Luo, J.M. Hu, A.M. Asiri, A.O. Al-Youbi, X.P. Sun Electrochimica Acta, 60 (2012)

[8] E. Jin, X.F. Lu, L.L. Cui, D.M. Chao, C. Wang Electrochimica Acta, 55 (2010), p. 7230 [9] X.X. Liu, H. Zhu, X.R. Yang Talanta, 87 (2011), p. 243 [10] S. Woo, Y.R. Kim, T.D. Chung, Y. Piao, H. Kim Electrochimica Acta, 59 (2012), p. 509



Enantioselective Chiral N-doped Graphene Quantum Dots

Aslı İ. Doğan1*, Funda Çopur1, Erhan Zor2, Sabri Alpaydin3 and Haluk Bingol3

1 Institute of Science, Necmettin Erbakan University, Konya/Turkey

2 Department of Science Education, Necmettin Erbakan University, Konya/Turkey 3 Department of Chemistry Education, Necmettin Erbakan University, Konya/Turkey


Abstract

Although the enantiomers of chiral molecules taking a

fundamental place in chemistry, biochemistry and

pharmacology have identical chemical and physical properties, they may exhibit different reaction ability in

stereochemical reactions [1]. Within this context,

enantiomeric recognition of chiral molecules by

different chiral selector is becoming one of the most

important fields in analytical chemistry especially for

pharmaceutical industry, clinical analysis, food analysis

and forensic analysis. The commercial analytical

techniques for recognizing enantiomers are usually

based on high performance liquid chromatography and

capillary electro-chromatography. Due to the

advantages such as the low-cost, detection limits etc., a number of studies and reviews have been published

related to spectrofluorometric method which is one of

the most preferred methods. In these studies, small

organic molecules, macrocyclic compounds, metal

complexes, polymers and nanomaterials have been used

as sensors in the stereochemical reactions. With the

advances in nanotechnology over the past two decades,

nanomaterials have been used almost in all areas and an

increasing attention is focused on chiral detection

studies. Among them, graphene quantum dots (GQDs)

are emerging as promising fluorescent materials for

biological applications, owing to their unique properties, such as excellent biocompatibility and

solubility in physiological conditions [3].

Herein, a novel route to prepare different types of light-

emitting chiral nitrogen-doped GQDs (cN-GQDs) is

demonstrated by a hydrothermal process between GQDs

and D-/L-PA as chiral precursors. The purified cN-

GQDs with silica column showed different emission

properties based on their stereochemical moiety. cN-

GQDs were synthesized in three steps. As the first step,

graphene oxide (GO) was prepared by following the

improved Hummers method. In the second step regarding the conversion of GO to nitrogen-doped

GQDs (N-GQDs), the further cutting and in situ doping

progress of GO was performed in DMF media using a

Teflon-lined autoclave at 200 °C for 4 h [4]. After

cooling, filtering and centrifuging, in the last step, N-

GQDs were converted to cN-GQDs by applying the

second hydrothermal process at 180 °C for 24 h

between GQDs and D-/L-PA [5]. The freshly as-

prepared cN-GQDs have been purified via silica column

chromatography (Fig. 2). The obtained cN-GQDs were

characterized by FT-IR, Raman, XPS and TEM. From

the purified products via silica column chromatography,

N-GQDs conjugated with L-PA (L-PA@N-GQDs)

shows a green photoluminescent (PL) at 505 nm, on the

contrary, D-PA@N-GQDs shows very week PL around

470 nm as can be seen in Figure 1. The corresponding PL spectra showing excitation and emission changes for

both materials are also given in Figure 1.

Figure 1 Column chromatography for purification,

photographs under daylight and UV light, and

excitation and emission spectra of cN-GQDs.

We also explored the feasibility of fluorescent L-

PA@N-GQDs for the selective chiral recognition of

chiral amino acids. Among them, the different quenching behaviors were observed when cysteine

enantiomers were added into the aqueous solution of

fluorescent L-PA@N-GQDs.

We express our deep thanks to the Scientific and

Technological Research Council of Turkey (TÜBİTAK)

for financial support (215Z222).

References

[1] Izake E.L., J. Pharm. Sci., 96 (2007), 1659–1676.

[2] Suzuki N. et al., ACS Nano 10 (2016) 1744-1755.

[3] Li X.et al., Adv. Funct. Mater., 25(2015), 4929-47.

[4] Sun J. et al., Part. Part. Syst. Charact., 32 (2015), 434–440.

[5] Wang T.et al., Sci. Reports, 9591 (2015), 1-9.



Preparation and Characterization of Biopolymeric Microspheres for Medical

Applications

A. Gülsu1*, H. Ayhan2 and F. Ayhan2

1 Department of Molecular Biology and Genetics, University of Muğla Sıtkı Koçman

2 Department of Chemistry, University of Muğla Sıtkı Koçman


Abstract

Cellulosic polymers are widely applied in medicine and

generally regarded as biocompatible. It has wide

ranging applications, e.g. as separation medium, carrier

system and as adsorbent in extracorporeal blood

purification [1-7]. It has also found applications such as

for scaffolds in tissue engineering, temporary skin

substitute, haemostatic agent, postoperative adhesion

barrier, and as a culture material for hepatocytes [8]. As

a biopolymeric material, various forms of cellulose are generally recognized as safe. The aim of this work was

to prepare and characterize cellulose microspheres with

narrow size distribution preferentially in the use for

haemostatic agent, post-operative adhesion barrier, and

drug delivery.

Polysaccharide based cellulose microspheres were

prepared and stabilized by water/organic phase

emulsion system in chitosan media. The influence of

several parameters on the particle size distribution was

assessed. Various processing and formulation

parameters such as stirring speed, volume of processing

medium and evaporation temparature were optimized to have narrow size distribution.

The optical micrographes and SEM images of

biopolymeric microspheres were taken for the

characterization studies after preparation. The prepared

cellulose microspheres were white and spherical in

shape, stable in nature, 2% chitosan concentration, 1400

rpm stirring rate, 40oC solvent evaporation temperature

were determined as optimal conditions. The size

distribution of cellulose microsphere was 5% <2 µm,

80% 3-5 µm, 10% 7-9 µm at these preparation

conditions.

Fig 1. Optical micrograph of cellulose microsheres

Fig 2. SEM photograph of cellulose microsheres

References

[1] de Oliveira W, Glasser WG (1996b) Hydrogels from

polysaccharides. II. Beads with cellulose derivatives. J Appl Polym Sci 61:81–86

[2] Kuga S (1980) New cellulose gel for

chromatography. J Chromatogr 195:221–230

[3] Kaster JA, de Oliveira W, Glasser WG, Velander WH

(1993) Optimization of pressure-flow limits, strength,

intraparticle transport and dynamic capacity by hydrogel

solids content and bead size in cellulose

immunosorbents. J Chromatogr A 648:79–90

[4] Wolf B, Horsch W (1991) Herstellung,

Eigenschaften und Verwendung der Perlcellulose—eine

U ¨ bersicht. Pharmazie 46:392–402

[5] Wolf B, Schmitz W, Schneider H (1996) Composites of bead cellulose and hydrophilic solubiliziers. Int J

Pharm 139: 87–94

[6] Pes ˇka J, S ˇtamberg J, Hradil J, Ilavsky ´ M (1976)

Cellulose in bead form: properties related to

chromatographic uses. J Chromatogr 125:455–469

[7] Volkert B, Wolf B, Fischer S, Li N, Lou C (2009)

Applications of modified bead cellulose as a carrier of

active ingredients. Macromol Symp 280:130–135

[8] Hoenich N (2006) Cellulose for medical

applications.BioResources1(2):270-280



Carbon Quantum Dots Embedded Nanopaper for Iodide Sensing

Aylin Arıcı1*, Erhan Zor2, Ahmet O Saf3, Sabri Alpaydin3 and Haluk Bingol3

1 Institute of Science, Necmettin Erbakan University, Konya/Turkey

2 Department of Science Education, Necmettin Erbakan University, Konya/Turkey

3 Department of Chemistry Education, Necmettin Erbakan University, Konya/Turkey


1. Introduction

Nanomaterial engineering technologies have the

potential to revolutionize simple and disposable sensing

systems. In this respect, paper-based (bio)sensors

provide new opportunities and directions in the

development of precise and sensitive analytical devices.

With the recent advances in flexible and transparent

sensor (nano)technology, nanopaper-based sensors have

attracted great attention of researchers [1]. Common

paper is made of cellulose fibers with an average diameter of ~25 µm inducing significant light scattering

that results in an opaque substrate. However, nanopaper

is a transparent film due to the network-forming of

nanocellulose fibers which are several micrometers long

with a diameter below 100 nm. In addition, nanopaper is

capable of adsorbing various kinds of ions, such as

heavy metal ions or cationic dyes, via electrostatic

interaction between functional groups and ions [2]. By

incorporating nanoparticles/dots, nanopaper may exhibit

selective detection of different kind of ions and may

give an analytical signal. Nanopaper-based platforms has been scarcely used for optical (bio)sensing

applications and even no published study exists for

carbon quantum dots embedded photoluminescent

sensors to date. Hence, we sought to fabricate and test a

simple and disposable nanopaper-based sensing

platform for “yes/no” type detection of iodide (I-) anion.

2. Experimental

To prepare nitrogen doped carbon quantum dots (N-CQDs), 0.5 g citric acid was firstly mixed with 55 mg

HMDA. The mixture was heated to 240 ˚C using a

teflon-lined autoclave. Subsequently, the color of the

melting mixture changed from colorless to pale brown.

The resultant N-CQDs solution was purified within the

dialysis bag (MWCO: 2kDa) [3]. PL spectra of the

purified N-CQDs showing excitation and emission

changes were given in Figure 1.

Figure 1 The excitation and emission spectra of N-

CQDs.

Bacterial cellulose nanopaper was fabricated using

Acetobacter xylinum bacteria in 50 g glucose, 5 g yeast

extract, 5 g (NH4)2SO4, 4 g KH2PO4 and 0.1 g

MgSO4.7H2O in 1 liters of water for two weeks at 28 ˚C

[1]. Figure 2 shows SEM images of nanopaper at low

and high magnifications.

Figure 2 SEM images of nanopaper

For sensing experiments, N-CQDs were embedded into

nanopaper by immersing in solution of N-CQDs. Then, paper was dried in drying oven at room temperature.

The resultant N-CQDs-embedded nanopaper was cut to

prepare desired disposable sensors and treated with the

sodium salts of anions (acetate, nitrate, sulfate, fluoride,

chloride, bromide and iodide) by syringing on them. As

easily seen in Figure 3, the green luminescent of N-

CQDs embedded transparent nanopaper was quenched

only in the presence of I- whereas no change was

observed for the other tested anions which demonstrates

that N-CQDs embedded nanopaper could be used as an

effective disposable sensing platform for I- anion.

Figure 3 Nanopaper treated with the sodium salts of the

corresponding anions

References

[1] Morales-Narvàez et al., ACS Nano, 2015, 9 (7),

7296–7305

[2] Mautner et al., Environ. Sci.: Water Res. Technol.,

2016, 2, 117–124.

[3] Liu et al., Nanoscale, 2013, 5, 1810–1815.



A High Performance Enzyme-Free Glucose Sensor Based on the Activated

Carbon decorated Ni/Pd Nanocomposites

Fatih Şen1, Yağmur Koşkun1 and Aysun Savk1*

1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupınar University, Kütahya,

Turkey


Abstract

Herein, an ultrasensitive and reliable non-enzymatic

electrochemical glucose sensor has been developed,

which is based on mesoporous Ni/Pd@AC

nanoparticles prepared by a facile route aided by

ultrasonication under mild conditions [1]. The

fabricated glucose sensor is capable of detecting glucose

with a wide linear region of 0.01–2 mM and an ultralow

detection limit of 10 µM. The Ni/Pd@AC

nanocomposite was characterized by transmission

electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) and UV–

vis spectroscopy [2]. The nanoparticles have also

exhibited favorable properties such as good selectivity,

reproducibility, durability and real sample analysis,

which ensured its potential applications in the clinical

diagnosis of diabetes [3].

Figure 1 . Cyclic voltammograms of NiPd/AC in 0.1 M NaOH of pH 7.0 at different scan rates: (a) 20;

(b) 40; (c) 60; (d) 80; (e) 100; (f) 120; (g) 150; (h)

200 mV/s-1.

References

[1] Wang L, Lu X, Ye Y, Sun L, Song Y (2013) Nickel-

cobalt nanostructures coated reduced graphene oxide

nanocomposite electrode for nonenzymatic glucose

biosensing. Electrochim Acta 114, 484–493.

[2] A.A. Athawale, S.V. Bhagwat, P.P. Katre, (2006);

Nanocomposite of Pd-polyaniline as a selective

methanol sensor, Sensors Actuators B Chem. 114 263–

267.

[3] Wang G, He X,Wang L, Gu A, Huang Y, Fang B,

Geng B, Zhang X (2013) Non-enzymatic electrochemical sensing of glucose. Microchim Acta

180:161–186.




Performance Enhancement of Micro-scale Microbial Fuel Cells (µMFC) for

Nanoscale Power Generation

B. Şen Doğan1*, Nilüfer Erkal3, Ebru Özgür3, Özge Zorlu3 and H. Külah2, 3, 4

1 Department of Micro and Nanotechnology, METU,

2 Department of Electrical and Electronics Engineering, METU 3 Mikro Biyosistemler Inc., Ankara

4 METU-MEMS Research and Application Center, Ankara


1. Introduction

µMFCs are small bioreactors converting the energy in

the chemical bonds of organic matter into electrical

energy through catalytic activity of microorganisms

under anaerobic conditions. To obtain higher

performance µMFCs, the internal resistance of µMFC

can be decreased, the start-up time can be decreased or

the biofilm formation quality can be increased. Biofilm

is the complex structure adhering to surfaces that are regularly in contact with liquid substrate (organic

matter) consisting of colonies of bacteria.

2. Design

Optimization of chamber and/or cell geometries,

chamber or electrode materials, and electrode surface

characteristics is crucial to increase µMFC performance.

Thus, MEMS based µMFC electrodes are designed and

fabricated.

µMFC systems are operated under different loads or

open circuit with a Nafion 117 proton exchange

membrane. Shewanella Oneidensis MR-1is preferred to

be the biocatalyst. Triptic Soy Broth is fed as anolyte (3 µL/min) and 100 mM K3[Fe(CN)6] in phosphate buffer

(5 µL/min) is fed as catholyte. With the design given in

Figure 1, the internal resistance is calculated as ~20 kΩ

under these conditions.

Figure 1 Schematic of µMFC

3. Results

The start-up time of the biofilm formation and the effect

of different loads are investigated.

Figure 2 Effect of load on biofilm formation

Table 2 Comparison of performance values

25 kΩ

loaded

10 kΩ

loaded

Qian et al,

2009

Bacteria S. Oneidensis

MR-1

S. Oneidensis

MR-1

S. Oneidensis

MR-1

Anode area 0.61 cm2 0.61 cm2 0.15 cm2

Anode volume 10.4 µL 10.4 µL 1.5 µL

Anode/cathode materials

Au/Au Au/Au Au/carbon cloth

Volumetric power density

133 µW/cm3 26 µW/cm3

15 µW/cm3

Volumetric

current density

716 µA/cm3 500

µA/cm3

670

µA/cm3

Areal power density

2 µW/cm2 0.4 µW/cm2

0.15 µW/cm2

Areal current density

12 µA/cm2 9 µA/cm2 6.7 µA/cm2

4. Conclusions

Acclimatization of µMFC under a load resulted in

shorter start-up time. Power and current densities

obtained is comparable to similar literature study. When

the load is closer to internal resistance of the µMFC,

higher power and current densities are achieved.

References

[1] F. Qian, M. Baum, Q. Gu, and D. E. Morse, “A 1.5

µL microbial fuel cell for on-chip bioelectricity

generation,” Lab Chip, vol. 9, no. 21, p. 3076, 2009.



Detection of FV Leiden Mutation with Electrochemical DNA Biosensor

without Indicator

Berrin Tuğrul1*

1Molecular Biology Department, Biology Division, Faculty of Science and Letter, Manisa Celal Bayar University.

Manisa, Turkey


1. Aim

The method based upon detecting the hybridization

between probe and target sequences without indicator

according to Guanin oxidation signalling in DNA is

defined as identification with electrochemical DNA

biosensor without indicator. This study aimed at

detecting the G → A change in the 1691th nucleotide

of FV gene (FV Leiden) by electrochemical DNA

biosensor without indicator.

2. Material and Method

In this study, PCR products of 224 bp amplified from

FV gene were used. Of 40 PCR products detected by

Restriction Fragment Lenght Polymorphism (RFLP)

method , 20 were heterozygous, 5 homozygous and 20

wild type (Figure 1). Synthetitic oligonucleotides,

random sequence (21 mer belong to HBV), PCR

products diluated in the ratio of 1/40 and denaturated

were hybrydized with carbon paste electrode (CPE) to

whose surface 23 mer probe (wild / mutant) was

attached. Results of hybridization were measured in

differential pulse voltammetry (DPV) between 0.75V

and 1.4V range The consistency of the obtained results

was evaluated statistically by Kappa (к) Methods.

3. Results

The results of Guanin signalling obtained through the

hybridization between the wild type probe with inosine

and target sequences were found as 75-80 nA for wild

type persons, 20-25 nA for heterozygous persons, and

no signalling for homozygous persons (Figure 2). The

results of Guanin signalling obtained through the

hybridization between mutant probe with inosine and

target sequences were determined as no signalling, 20-

25 nA and, 75-80 nA, for wild type, heterozygous and

homozygous persons, respectively (Figure 3). When

compared statistically, the results of electrochemical

DNA biosensor and RFLP were found to be compatible

with each other (kappa (ĸ)=1).

4. Conclusion

FV Leiden mutation, by using electrochemical DNA

biosensor without indicator, could be detected as

heterozygous and homozygous according to different

Guanin signalling.

Keywords: Differential Pulse Voltametry,

Electrochemical DNA biosensor, FV Leiden, RFLP

Figure 1. The results of RFLP obtained from PCR

products. 1. pUC19 DNA/MspI (HpaII) Marker, 23, 2.

PCR product of 224bp., 3. RFLP Product of

homozygous genotype 4, 9. RFLP product of

heterozygous genotype 5, 6, 7, 8. RFLP products of wild

type genotype

Figure 2. Differential pulse voltammograms (A1) and histogram (A2) the results of Guanin signalling

obtained through the hybridization between the wild

type probe with inosine and target sequences

Figure 3. Differential pulse voltammograms (A1) and

histogram (A2) the results of Guanin signalling

obtained through the hybridization between mutant

probe with inosine and target sequences



-0,2 0,0 0,2 0,4 0,6 0,8

0,0

60,0µ

120,0µ

180,0µ

240,0µ

300,0µ

360,0µ

I/A

E/V

A

UA

DA

AA

F

Pt-Co nanoparticles decorated reduced graphene oxide for ultrasensitive dopamine,

ascorbic and uric acid detection

Fatih Sen1, Sait Bozkurt1 and Betül Sen1*

1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupinar University, Kütahya,

Turkey


Abstract

Graphene is chemically synthesized by Hummers

method reduction of colloidal dispersions of graphite

oxide [1-2]. Electrochemical characterization of

graphene modified Pt-Co (rGO/Pt-Co) is carried out by

cyclic voltammetry (CV). The behavior of rGO/Pt-Co/GCE towards ascorbic acid (AA), dopamine (DA)

and uric acid (UA) has been investigated by CV,

differential pulse voltammetry (DPV) and

chronoamperommetry (CA). The rGO/Pt-Co/GCE is

successfully used for the simultaneous detection of AA,

DA and UA in their ternary mixture and DA in serum

and pharmaceutical samples. The excellent

electrocatalytic behavior of rGO/Pt-Co/GGE may lead

to new applications in electrochemical analysis [1-2].

Figure: DPV results of AA, DA and UA at GCE,

rGO/Pt-Co modified electrodes.

References

[1] F. Gonan, M. Buda, R. Cespuglio, M. Jouvet, J.-F.

Pujol, In vivo electrochemical detection of catechols in the neostriatum of anaesthetized rats: dopamine or

DOPAC Nature 286 (1980) 902–904.

[2] P. Ramesh, G.S. Suresh, S. Sampath, Selective

determination of dopamine using unmodified, exfoliated

graphite electrodes, J. Electroanal. Chem. 561 (2004)

173–180.



A novel sensitive electrochemical sensor based on reduced graphene oxide

decorated Pt nanocomposites for simultaneous determination of uric acid (UA)

Fatih Sen1, Ceyda Ulutürk1 and Betul Sen1*


Turkey


Abstract

In this paper, Pt -reduced graphene oxide–ZnO (Pt-

ZnO/rGO) nanoparticle composites was prepared by

simple and effective chemical routes. The synthesized

Pt-ZnO/rGO nanoparticle composite has been

successfully applied for glassy carbon electrode (GCE)

surface modification[1]. The Pt-ZnO/rGO nanoparticle -

modified GCE was applied for sensitive and selective

determination of uric acid (UA) [2]. The biosensor

exhibited a linear dependence on UA concentration

ranging from 10 to 750 μM with a detection limit of 0.510 μM (S/N=3). The proposed UA sensor also

showed an excellent stability, reproducibility and anti-

interference property[3-4].

Figure 1 Cyclic voltammograms of the Pt-ZnO/rGO -

modified GCE at scan rate of 20–200mVs−1 in 0.1 M

PBS containing 1mM UA[4].

References

[1] Sun, Z.; Fu, H.; Deng, L.; Wang, J.: Redox-active

thioninegraphene oxide hybrid nanosheet: one-pot,

rapid synthesis, and application as a sensing platform

for uric acid. Anal. Chim.Acta 761, 84–91 (2013).

doi:10.1016/j.aca.2012.11.057

[2]Yang,L.,Liu,D.,Huang,J.S.,You,T.Y.,2014.Sens.Actua

torsB:Chem.193,166–172.

[3] Y.F. Zhao, Y.Q. Gao, D.P. Zhan, H. Liu, Q. Zhao, Y.

Kou, Y.H. Shao, M.X. Li, Q.K. Zhuang, Z.W. Zhu

Talanta, 66 (2005), pp. 51–57 [4] C.F. Tang, S.A. Kumar, S.M. Chen Anal. Biochem.,

380 (2008), pp. 174–183



Radiation Synthesis of Superadsorbent Conducting Smart Polymer/Pumice

Nanocomposite Hydrogels

B. Taşdelen1*

1Department of Biomedical Engineering, Namık Kemal University, No:13 59860 Çorlu, Tekirdağ


Abstract

Stimuli-responsive hydrogels with decent electrical

properties are a promising class of polymeric materials

For a range of technological applications, such as

electrical, electrochemical and biomedical devices ction

Smart hydrogels which are sensitive to external stimuli

such as temperature, pH, electric field, magnetic force,

etc. could react actively to environmental changes, thus

receiving increasing attention in recent years [1].

However, traditional smart hydrogels are generally

nonconductive while conductive gels hold great promise for a wide range of applications in sensors, fuels cells,

supercapacitors, dye-sensitized solar cells and lithium

batteries [2]. Polyaniline (PANI) is a well-known

conducting polymer, discovered in the late 19th century

and still under investigation due to the excellent

compromise between favorable properties and cost [4].

Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels are

typical thermosensitive materials. They change their

volume abruptly and significantly on temperature

variations from external environments and exhibit a

lower critical solution temperature (LCST) at about 33°C [3]. Due to their unique properties, PNIPAAm

hydrogels found their applications in chemical devices,

tissue engineering, separation, microfluidic actuators,

biomedical fields. Radiation induced in-situ

polymerization and crosslinking, which can be carried

out at room temperature without initiators and catalysts

are safe, clean and effective method for the synthesis of

the hydrogels Use of pumice for removal of pollutants

by various treatment technologies, mainly adsorption

has become popular during last decade. Turkey has

quite significant potential with respect to pumice

reserves. In this work, semi-IPN poly(acrylamide-co-maleic acid)/polyaniline composite hydrogel was

successfully synthesized by two-steps gamma radiation

induced polymerization in aqueous solution. First,

NIPAAm /itaconic acid (IA) copolymeric hydrogels

were prepared by irradiation of the ternary mixtures of

NIPAAm/IA/water in the presence of pumice by γ-rays

at ambient temperature. Poly(NIPAAm-co-IA)/PANI

hydrogels possessed a high electrical conductivity.

NIPAAm/IA hydrogels were prepared by using gamma

rays irradiation copolymerization of NIPAAm monomer

with addition of an anionic comonomer, namely IA. To prepare highly swollen NIPAAm/IA hydrogel systems,

NIPAAm weighing 10 g was dissolved in 100 mL water

in the presence of pumice. Then, 120 mg of IA were

added to each NIPAAm solution. Monomer solutions

thus prepared were placed in a glass tube with 5 mm

inner diameter. All irradiations were carried out under irradiation in air at dose of 48 kGy at ambient

temperature. Small discs of dry (ca. 0.1 g) of

crosslinked PNIPAAm (homopolymer or copolymer

with IA) hydrogel were immersed in monomer solution

of aniline (AN) in aqueous solution of 1 M HCl (3 mL),

until all the solution was absorbed into the hydrogel

(taking 3 hour at least). These solutions were transferred

to small glass tubes of 5 mm in diameter and irradiated

at dose of 48 kGy in air at ambient temperature under irradiation.

In this work, we study the synthesis of NIPAAm based

hydrogels semi-interpenetrated with polyanilines and

the effect of copolymerization with IA and semi-interpenetration on swelling capacity. We propose a

novel alternative method to incorporate a conductive

linear polymer (PANI) inside a network of pH-sensitive

hydrogel under γ-irradiation at room temperature. In our

study, poly(NIPAAm/IA) three dimensional network is

formed after the first radiation induced polymerization.

Since aniline monomer inside of PNIPAAm network,

the polyaniline chain is formed inside of the

polyacrylamide network during the second

polymerization. The composite hydrogels with good

conductive properties also displayed unique pH and temperature sensitivity. Significantly, the present

findings have tested by embedding a conductive

polymer with a unique morphology via in situ radiation

grafted induced polymerization rather than the usual

blending method would help in the design of drug

delivery systems based on pH and temperature-sensitive

and conductive polymers in biologic media.

Figure 1. Schematic representation of s-IPN

poly(NIPAAm-co-IA)/PANI hydrogels.

References [1] D. Li, X. Zhang, J. Yao, G.P. Simon, H.Wang, Chem. Commun. 2011, 47, 1710. [2] L. Qiu, D.Liu, Y. Wang, C. Cheng, K.Zhou, Adv. Mater,

2014, 26, 3333. [3] Y. Hirokawa, T. Tanaka, J Chem Phys 1984, 81, 6379.



Protein Adsorption on SAM Modified SiO2 Surfaces

B. Garipcan1*, and D. Hür2, L. Uzun3, F. Kuralay4 and S. Eren1

1 Institute of Biomedical Engineering, Boğaziçi University,

2 Department of Chemistry, Anadolu University, 3Department of Physics, Chemistry, and Biology, Linköping University

4Department of Chemistry, Ordu University


5. Introduction

Protein adsorption is one of the important issues that

can help to understand cell-surface interaction

mechanisms. As the matter of fact that, protein

adsorption is as a precursor of cell-surface interaction

and plays a significant role to indicate biocompatibility

of a biomaterial [1,2]. In this study, novel amino acid

(conjugated histidine, leucine) conjugated self-

assembled molecules (SAMs) were synthesized and

used to modify SiO2 surfaces to investigate protein adsorption.


Novel amino acid (histidine, leucine) conjugated SAMs

were synthesized in our laboratory, which have special

affinity to SiO2 surfaces and attracted by chemisorption

[4]. Syntheses of amino acid conjugated SAMs were

characterized with H1 - Nuclear Magnetic Resonance

(1H-NMR) Spectroscopy.

SiO2 surfaces were modified 3-(trimethoxysilyl)propane

functional groups conjugated amino acids for (histidine

and leucine), respectively. Substrates were modified in-

situ in flow cell during QCM (SRS, CA, USA)

frequency measurement. 10mM SAM solutions were

used for modifications.

Modified SiO2 surfaces were characterized by water

contact angle measurements and XPS analysis.

It is aimed to manipulate and change the adsorption of

proteins (Albumin, Fibrinogen and Immunoglobulin G)

on the surfaces using amino acid conjugated SAMs.

Protein adsorption was investigated in-situ by using Quartz Crystal Microbalance biosensors. According to

results, target proteins have shown different affinity to

amino acid conjugated SiO2 coated crystals depending

the type of the amino acids and concentration.

7. Results and Discussions

In this study, aim of protein adsorption investigation

part was manipulation of the protein adsorption by

surface modifications. The surface modifications were

proved by QCM frequency measurement, water contact

angle measurement, and XPS analysis before protein

adsorption investigations.

According to results of the protein adsorption study,

fibrinogen has shown the highest affinity to Leu-SAM.

In addition, Leu-SAM has highest affinity for all

proteins than His-SAM. Albumin and IgG have higher

affinity to Leu-Silane than His-Silane.

Figure 1. Fibrinogen adsorption results of 10mM His-Silane

and Leu Silane modified SiO2 surfaces. Δ frequency results (Hz)

in PBS: 7.4 at RT.

8. References

[1] C. Fornaguera, G. Caldero, M. Mitjans M.P. Vinardell, C. Solans,

C. Vauthier, ”Interactions of PLGA nanoparticles with blood

components: protein adsorption, coagulation, activation of the

complement system and hemolysis studies” Nanoscale, 7, 6045-58,

2015

[2] Yang, D., X. Lu, Y. Hong, T. Xi, and D. Zhang, “The molecular

mechanism of mediation of adsorbed serum proteins to endothelial

cells adhesion and growth on biomaterials,” Biomaterials, Vol. 34, pp.

5747–5758, 2013.

[3] C.K. Akkan, D. Hür, L. Uzun, B. Garipcan, “Amino Acid

Conjugated Self Assembling Molecules for Enhancing Surface

Wettability of Fiber Laser Treated Titanium Surfaces”, Applied

Surface Science, 366,



A sensitive immunosensor based on indium tin oxide electrodes modified with

carbonyldiimidazole and silane for determination of TNF-α

Burcu Özcan1* and Mustafa Kemal Sezgintürk2

1 Namik Kemal University, Faculty of Arts and Science, Chemistry Department, Biochemistry Division, Tekirdag,

Turkey


1. Introduction

Tumor necrosis factor α (TNF-α) is a recognized marker

of the obesity-related inflammatory state [1], and DNA

methylation pattern of its promoter in blood cells is able

to predict the response to a hypocaloric treatment in

humans [2]. TNF-α increases the expression of adhesion

molecules on the endothelium and smooth muscle cells

as has been shown in isolated animal and human

vascular cells [3], and these molecules also impair the

insulin signaling cascade. TNF-α also suppresses insulin signal transduction and expression of the insulin

receptor in isolated adipocytes, which leads indirectly to

glucose dysregulation and hyperglycemia, and eventual

pancreatic β-cell destruction. TNF-α is also associated

with CAD, infarction, stroke, thrombosis and peripheral

arterial disease [4]. Silane coupling agents containing

carboxylate groups may be used to functionalize a

surface with carboxylic acids for subsequent

conjugation with amine containing molecules.

Carboxyethylsilanetriol contains an acetate organo

group on a silanetriol inorganic reactive end. The

silanetriol component is reactive immediately with inorganic –OH substrates without prior hydolysis of

alkoxy groups, as in the case with most other

silanization reagents. Carboxyethylsilanetriol has been

used to add carboxylate groups to fluorescent silica

nanoparticles to couple antibodies for multiplexed

bacteria monitoring [5].


In this study, a biosensor based on ITO (indium tin

oxide) electrode was designed to determine TNF-α.

Firstly, ITO electrodes were modified with NH4OH/ H2O2/H2O to obtain the OH groups on the surface.

Later, the surface of ITO electrodes were treated with

carboxyethylsilanetriol. After SAM formation, 1,1’-

carbonyl diimidazol was used to interact with carboxyl

groups in carboxyethylsilanetriol solution. Anti- TNF-α

was covalently immobilized on modified ITO

electrodes.

Optimization steps are very important and necessary to

construct a good, stable, repeatable and reproducible

biosensor. For this purpose, all parameters such as

SAMs concentration, 1,1’ carbonyl dimidazol concentration and incubation time, anti-TNF-α

concentration and incubation time were optimized. For

determining the immobilization steps and optimization

of the biosensor, electrochemical impedance

spectroscopy (EIS) and cyclic voltammetry (CV) were

used.

Acknowledgement: This study was supported by The


Turkey (TUBİTAK) by the project number of 113 Z

678.

3. References

[1]Odrowaz-Sypniewska G. (2007) Markers of

proinflammatory and pro-thrombotic state in the

diagnosis of metabolic syndrome. Adv Med Sci.

52:246–250

[2] Campion J, Milagro FI, Martinez JA (2009)

Individuality and epigenetics in obesity. Obes Rev

10:383–392.

[3] Lyon CJ, Law RE, Hsueh WA. Minireview:

adiposity, inflammation, and atherogenesis.

Endocrinology 2003; 144: 2195–2200.

[4]Weyer C, Yudkin JS, Stehouwer CD, Schalkwijk CG, Pratley RE, Tataranni PA. Humoral markers of

inflammation and endothelial dysfunction in relation

to adiposity and in vivo insulin action in Pima

Indians. Atherosclerosis 2002; 161: 233–242.

[5]Greg T. Hermanson, Functional Silane Compounds.

Bioconjugate Techniques. Third edition. 2013.



Label-free electrochemical immunosensor based on indium tin oxide as a

electrode material for detection of tumor necrosis factor-

Burçak Demirbakan1* and Mustafa Kemal Sezgintürk2

1 Namik Kemal University, Faculty of Arts and Science, Chemistry Department, 2 Biochemistry Division ,Tekirdag, Turkey


1. Introduction

Pro-inflammatory cytokine tumor necrosis factor alpha

(TNF-) is a 157-amino acid long polypeptide with an apparent molecular weight of 51 kDa when exists as a

trimer [1,2]. It mediates a variety of cell functions,

including the stimulation of nitric oxide (NO)

production which has been related to oxidative stress and diseases such as stroke, diabetes, severe

meningococcemia, rheumatoid arthritis, and chronic

inflammation [3–4]. Research has shown that TNF- is not produced by normal cells, but rather to be induced

by invasive stimuli in the setting of both endoplastic and

infectious disease. Therefore, the development of

sensitive methods for detection of TNF- is particularly important for biomedical research and clinical

diagnosis. Aldehyde (CHO) functionalities have been

utilized as supports for protein immobilization via

electrostatic and covalent interactions, respectively. The

use of aldehyde termini has the advantage of forming

strong covalent bonds with the primary amines in the

protein residues [5].


In this study, we designed a novel biosensor to detect

TNF- biomarker constructed on modified indium tin

oxide (ITO) disposable electrodes. Anti- TNF- was immobilized through covalent 11-(triethoxysilyl)

undecanal which formed a self-assembled monolayers

(SAMs) on modified ITO electrodes. Analytical

characteristics such as square wave voltammetry, linear

determination range, repeatibility, reproducibilty and

regeneration of biosensors were determined. All

characterization steps were monitored by Cyclic

Voltammetry (CV), and Electrochemical Impedance

Spectroscopy (EIS) techniques. To achieve reproducible

and repeatable biosensor system, all parameters such as

SAMs concentration, antibody concentration and antibody incubation time were optimized. The presented

biosensor has wide determination range (5 fg-75

fg/mL).

This study illustrates development of the biosensor for

the determination of tumor necrosis factor alpha (TNF-

). For this purpose, firstly the biosensor was based on indium tin oxide (ITO) disposable electrodes modified

with 11-(triethoxysilyl) undecanal. Cyclic

voltammetry (CV) and electrochemical impedance

spectroscopy (EIS) methods were applied to

characterize the immobilization of anti- TNF- process

and to determine TNF-. Analytical characteristics such as square wave voltammetry, linear determination

range, repeatibility, reproducibilty and regeneration of

biosensors were determined. For expounding binding

characterization of TNF- and anti- TNF- single frequency impedance method was utilized. Scanning

electron microscopy was used for identifying the

surface morphology and Kramers-Kronig transform was

implemented on impedance datum. The biosensor has exhibited good repeatability and reproducibility. Linear

range of developed biosensor was 0.03 pg – 3 pg/mL.

To verify the availability of the biosensor, the human

serum samples were experienced.

Acknowledgement: Authors are thankful The Scientific

and Technological Research Council of Turkey

(TUBİTAK) by the project number of 113 Z 678.

References

[1] F. Bettazzi, L. Enayati, I.C. Sanchez, R. Motaghed,

M. Mascini, I. Palchetti, Electrochemical bioassay for

the detection of TNF-alpha using magnetic beads and

disposable screen-printed array of electrodes,

Bioanalysis 5 (2013) 11–19. [2] Y. Liu, W. Zhang, X. Yu, H.W. Zhang, R. Zhao, D.

Shangguan, Y. Li, B.F. Shen, G.Q. Liu, Quartz crystal

biosensor for real-time kinetic analysis of interaction

between human TNF-alpha and monoclonal antibodies,

Sens. Actuators B Chem. 99 (2004) 416–424.

[3] Y. Liu, Q. Zhou, A. Revzin, An aptasensor for

electrochemical detection of tumor necrosis factor in

human blood, Analyst 138 (2013) 4321–4326

[4] R. Say, S.E. Diltemiz, S. Celik, A. Ersoz, Nanolabel

for TNF-alpha determination, Appl. Surf. Sci. 275

(2013) 233–238. [5]. A. Riposan, Y. Li, Y. H. Tan, G. Galli, G. Liu,

Structural Charactrerization of Aldehyde-Terminated

Self-Assembled Monolayers, Department of Chemistry

111 (2007) 12727-12739.


mailto:*Presenter:%[email protected]


Preparation and Enzymatic Application of a Time Dependent Growth of

flower-like hybrid nanoflowers by horseradish peroxidase

Cevahir Altinkaynak1,2*, Melike Vecihe Koc1, Nalan Özdemir3 and Ismail Ocsoy1,2

1 Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey

2 Nanotechnology Research Center, Erciyes University, Kayseri, 38039 Turkey 3 Department of Chemistry, Faculty of Science, Erciyes University, Kayseri, 38039 Turkey


1. Introduction

Enzymes which catalyze reactions with high specificity

and very high rapidity are biocatalysts. Free forms of

enzymes have a short life time and this situation limites applications of enzymes in many areas. In order to

increase the stability, catalytic activity and reusability of

enzymes, many different immobilization methods are

used for this purpose. Recently, nanoflowers has gained

attention because the organic-inorganic hybrid

nanostructures present higher stability and activity

compared to free forms [1]. In this study, time

dependent growth of flower-like hybrid nanoflowers

(hNFs) were observed using HRP (Horseradish

peroxidase) enzyme as the organic portion and

CuSO4.5H2O as inorganic components. Then some characteristics of these synthesized nanostructures were

determined. To prove formation of mechanism, we have

tested different incubation times. And the main

controlling factors on the morphology were

investigated.

2. Experimental

The hybrid nanoflowers were synthesized using a

reported method [1,2,3] (Fig.1). First, CuSO4 stock

solution was prepared in ultrapure water. Then, certain

volume of that solution was added to PBS solution

containing 0.02 mg mL-1 HRP. The resulting mixture

was vigorously shaken for 30 seconds and incubated without disturbing at +4°C for 1, 3, 6, 12, 24, 48 and 72

hours. After incubation, the blue color precipitates were

collected and washed by centrifugation at 4000 rpm for

15 minutes. The washing process was repeated at least 3

times. The collected precipitates were dried 50°C under

vacuum. The structure of the synthesized hNFs was

confirmed by FT-IR, XRD, and EDX. The enzymatic

activities of hNFs and free horseradish peroxidase were

determined by measuring colorimetric and

spectroscopic methods using guaiacol as a substrate in

PBS buffer (pH 6.8).

Figure 1 The growth mechanism of hybrid nanoflowers

(A) nucleation and formation of primary crystals, (B)

growth of crystals (C) formation of nanoflowers


SEM images of synthesized hNFs were given in Fig.2.

Encapsulation yields of hybrid nanostructures were

calculated by determining HRP concentration in the supernatant (Table 1).

Table 1. The encapsulation yield of HRP hybrid

nanostructures

Different

incubation time

Protein Concentration

(mg/ml)

Encapsulation

Yield (%) Initial After

incubation

1 h

0,02

0,0060 70

3 h 0,0052 74

6 h 0,0042 79

12 h 0,0030 85

24 h 0,0022 89

48 h 0,0012 94

72 h 0,0004 98

Figure 2 SEM images of the

nanostructures (A) 1h (B) 3h (C)

6h (D) 12h (E) 24h (F) 48h (G)

72h

Most regular and uniform flower-shaped morphology

was observed at a 72h incubation. The nanoflower

exhibited the highest activity (120,39 EU/mg) compared

the free HRP (33,48 EU/mg) and nanoflower formed in

other incubation times. With these features, HRP has

been used in different scientific and technical

applications, such as removal of phenols from polluted

water, and biosensor design.

4. References [1] J. Ge, J. Lei and R.N. Zare, Nature Nano. 2012, 7, 428–432.

[2] B. Somtürk, M. Hançer, I. Ocsoy and N. Özdemir, 2015, Dalton Transactions

[3] C. Altinkaynak, İ. Yilmaz, Z. Koksal, H. Özdemir, I. Ocsoy, N. Özdemir, International

Journal of Biological Macromolecules, 84, 402-409 (2016).



0

200

400

Re

lavi

te A

ctiv

ity

(%)

Lipase-Cu+2 Lipase-Fe+2

Lipase-Zn+2

Synthesis of Lipase Based Hybrid Nanoflower through the Coordination

Chemistry and Their Excellent Activity

Cevahir Altinkaynak1,2*, Mehmet Yasar Dinler1, Nalan Özdemir3 and Ismail Ocsoy1,2

1 Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey

2 Nanotechnology Research Center, Erciyes University, Kayseri, 38039 Turkey 3 Department of Chemistry, Faculty of Science, Erciyes University, Kayseri, 38039 Turkey


1. Introduction

As natural biocatalysts, enzymes have received

considerable attention owing to their unique properties,

including high catalytic activity, stability, selectivity,

low toxicity and water-solubility. Accordingly, they

have found widespread use in various scientific and

technical fields, including chemistry, biochemistry,

medicine, pharmaceutical science and industry [1-3].

However, the instability of the free enzymes in aqueous

solution strictly limits their applications. To address this

issue, two common methods, chemical modification and

immobilization, have been used to enhance enzyme catalytic activity and stability. Recently, Zare and co-

workers reported an elegant approach for the synthesis

of immobilized enzymes in the form of nanoflower with

highly enhanced catalytic activity and stability [1].

These flower-like hybrid nano structures are developed

and used for various applications. In this study, lipase hybrid nanostructures were prepared

using different metal ions (Cu+2, Fe+2, Zn+2) and some

characteristics of them were determined. They can be

commonly used as components in kits for medical

applications and biosensors.

2. Experimental

The synthesis of nanostructures were accomplished

using a described method before [1,3,4]. In this

synthesis strategy, metal ions especially Cu2+ were

rationally and successfully combined with lipase to

form flower-like hybrid structures called “hybrid

nanoflowers (hNF)”. The proposed mechanism of

lipase-Cu+2 hNF formation is illustrated in Fig. 1.

Figure 1 Schematic illustration of the preparation

of hybrid nanoflowers

The structure of the synthesized lipase nanostructures

were scanned via SEM and characterized by FT-IR,

XRD, and EDX.

The catalytic activity of synthesized lipase nano

structures were evaluated by hydrolysis of olive oil and

oleic acid concentration was measured.


Encapsulation yields of lipase hybrid nanostructures

(0.1 mg mL-1) were calculated by determining lipase

concentration in the supernatant (Table 1).

Table 3 The encapsulation yield of lipase hybrid

nanostructures

Type Encapsulation Yield (%)

Lipase-Cu+2

93,11

Lipase-Fe+2

81,63

Lipase-Zn+2

87,37

The morphology of the lipase hybrid nanostructures

were demonstrated with SEM images in Fig. 2.

Figure 2 SEM images of the nanostructures (A)

Lipase-Cu+2 (B) Lipase-Fe+2 and (C) Lipase-Zn+2

The activity of the immobilized enzyme was higher than

the free enzyme. According to the free lipase enzyme;

Lipase 221.90% Zn-Fe-lipase 175.61% and 128.27% Cu

lipase showed greater of the activity.

At the end of 8 measurements it was found to be reused 60-80%.

4. References [1] J. Ge, J. Lei and R.N. Zare, Nature Nano. 2012, 7, 428–432.

[2] A. Atasever, H. Ozdemir, I. Gulcin, O. I. Kufrevioglu, Food Chem., 2013, 136, 864-870.

[3] B. Somturk, M. Hancer, I. Ocsoy and N. Özdemir, 2015, Dalton Transactions

[4] C. Altinkaynak, I. Yilmaz, Z. Koksal, H. Özdemir, I. Ocsoy, N. Özdemir, International

Journal of Biological Macromolecules, 84, 402-409 (2016).



Synthesis of Catecholamine-Metal İons Coordinated Hybird

Nanoflowers and Their Catalytic, Antioxidant and Antimicrobil

Properties

Çağla Çelik1* and Ismail Ocsoy1

1Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey


Abstract

Herein we report the preparation of organic–inorganic

nanoflowers formed of catecholamines and metal ions using a newly developed and an elegant immobilization

approach. While copper (II)/iron (II) metal ions were

used as inorganic component, epinephrine,

norepinephrine and dopamine were utilized as the

organic component. We also demonstrated how

dopamine (DA) based hybrid nanoflowers (HNFs) acted

as catalytic, antioxidant and antimicrobial agents. The

catalytic performances of DA-Cu2+ and Fe2+ HNFs were

evaluated as peroxidase-enzyme by oxidation of

guaiacol (2-methoxyphenol) to 3,3-dimethoxy-4,4-

diphenoquinone in the presence of hydrogen peroxide (H2O2) based on Fenton-like reaction. DA-Fe2+ HNFs

exhibited antioxidant activity towards 2,2-diphenyl-1-

picrylhydrazyl (DPPH). Finally, we also used the DA-

Cu2+ and Fe2+ HNFs as antimicrobial agent against

bacterial pathogens (Gram+ bacteria Staphylococcus

aureus and Gram- bacteria Escherichia coli) and fungal

pathogen (Candida albicans). We claim that HNFs

produced with this synthesis approach can be empolyed

in fabrication of biosensors and bioanalytical tools and

can be used in various scientific and technical fields.

Figure 1. (1) Illustration of plausible formation

mechanism of catecholamines–Metal2+ HNFs formed in

typical three successive steps (nucleation, growth and

completion). Potential uses ofthe HNFs as (2) catalytic,

(3) antioxidant and (4) antimicrobial agents.

Note: DA, E and NE represent dopamine and

epinephrine, norepinephrine, respectively

5. References

[1] J. Ge, J. Lei, R.N. Zare, Protein–inorganic hybrid

nanoflowers, Nat. Nanotechnol. 7 (2012) 428–432.

[2] Z. Wu, X. Li, F. Li, H. Yue, C. He, F. Xie, Z. Wang,

Enantioselective transesterification of (R,S)-2-pentanol

catalyzed by a new flower-like nanobioreactor, RSC

Adv. 4 (2014) 33998.

[3] B. Somturk, M. Hancer, I. Ocsoy, N. Özdemir,

Synthesis of copper ion incorporated horseradish

peroxidase-based hybrid nanoflowers for enhanced

catalytic activity and stability, Dalton Trans. 44 (2015)

13845–13852. [4] I. Ocsoy, E. Dogru, S. Usta, A new generation of

flowerlike horseradish peroxides as a nanobiocatalyst

for superior enzymatic activity, Enzyme Microbiol.

Technol. 75–76 (2015) 25–29.

[5] B. Somturk, I. Yilmaz, C. Altinkaynak, A. Karatepe,

N. Özdemir, I. Ocsoy, Synthesis of urease hybrid

nanoflowers and their enhanced catalytic properties,

Enzyme Microbiol. Technol. 86 (2016), 134–142.

[6] C. Altinkaynak, I. Yilmaz, Z. Koksal, H. Özdemir, I.

Ocsoy, N. Özdemir, Preparation of lactoperoxidase

incorporated hybrid nanoflower and its excellent

activity and stability, Int. J. Biol. Macromol. 84 (2016) 402–409.

[7] C. Altinkaynak, S. Tavlasogluc,, N. Özdemir, I.

Ocsoy, A new generation approach in enzyme

immobilization: Organic-inorganic hybrid nanoflowers

with enhanced catalytic activity and stability, Enzyme

Microbiol. Technol. 93 (2016) 105–112.



“Label-free impedimetric aptasensor for Ochratoxin‑A detection using Iridium

Oxide nanoparticles”

Lourdes Rivas1,2, Carmen C. Mayorga-Martinez1, Daniel Quesada-Gonzalez1*, Alejandro Zamora-Galvez1, Alfredo de

la Escosura-Muniz1 and Arben Merkoçi

1,3

1ICN2- Nanobioelectronics & Biosensors Group, Institut Catala de Nanociencia i Nanotecnologia, Campus UAB,

08193 Bellaterra (Barcelona), Spain 2Department de Quimica, Universitat Autonoma de Barcelona, 08193, Bellaterra (Barcelona), Spain

3ICREA- Institucio Catalan de Recerca i Estudis Avançatsi 08010 Barcelona, Spain


Abstract

Ochratoxin A (OTA) is a mycotoxin generated by

different fungi species such as Aspergillus and Penicillium during their growth. This toxin is a

hazardous contaminant present in a great number of

agricultural products such as cereals, coffee beans, dried

fruits, cocoa, nuts, beer and wine, causing economic

losses to agricultural trade [1]. Different methods are

routinely used for analysis of mycotoxins, such as

chromatography, enzyme-linked immunosorbent assay

(ELISA), and lateral flow assays (LFA), but label-free

and highly sensitive methods are still strongly required.

In this context, we present here [2] a novel aptasensor

for ochratoxin A (OTA) detection based on a screen-

printed carbon electrode (SPCE) modified with polythionine (PTH) and iridium oxide nanoparticles

(IrO2 NPs) [3, 4], which exhibit good stability,

biocompatibility and catalytic properties. The

electrotransducer surface is modified with an

electropolymerized film of PTH followed by the

assembly of IrO2 NPs on which the aminated aptamer

selective to OTA is exchanged with the citrate ions

surrounding IrO2 NPs via electrostatic interactions with

the same surface. Electrochemical impedance

spectroscopy (EIS) in the presence of the [Fe(CN)6]−3/−4

redox probe is employed to characterize each step in the aptasensor assay and also for label-free detection of

OTA in a range between 0.01 and 100 nM, obtaining

one of the lowest limits of detection reported so far for

label-free impedimetric detection of OTA (14 pM; 5.65

ng/kg). The reported system also exhibits a high

reproducibility, a good performance with a white wine

sample, and an excellent specificity against another

toxin present in such sample.

References:

1. Food and Agricultural Organization (FAO). Manual

on the application of the HACCP system in mycotoxin prevention and control; FAO: Rome, 2001; p 124.

2. Rivas, L.; Mayorga-Martinez, C.; Quesada-Gonzalez,

D.; Zamora-Galvez, A.; de la Escosura-Muniz, A.;

Merkoçi, A. Anal. Chem. 2015, 87, 5167−5172.

3. Mayorga Martinez, C.; Pino, F.; Kurbanoglu, S.;

Rivas, L.; Ozkan, S.; Merkoçi, A. J. Mater. Chem. B

2014, 2, 2233−2239.

4. Rivas, L.; de la Escosura-Muniz, A.; Pons, J.;

Merkoçi, A. Electroanalysis 2014, 26, 1287−1294.




Preparation of Carbon Paste Electrode containing Polyaniline-Activated

Carbon Composite for Amperometric Detection of Phenol

Halit Arslan1, Derya Yücel

2, Bekir Sıtkı Çevrimli

3, Hüseyin Zengin

4, Demet Uzun

1* and Fatma Arslan

1

1Department of Chemistry, Faculty of Sciences, Gazi University, 06500, Ankara, Turkey

2 Department of Chemistry, Institute of Sciences, Gazi University, Ankara, Turkey 3Department of Chemical Technology, Ataturk Vocational College, University of Gazi, 06500 Ankara, Turkey,

4Department of Chemistry, Faculty of Arts and Sciences, Gaziantep University, Gaziantep, Turkey


Abstract

Carbon paste electrodes are widely used in electro analysis owing to their low background current, wide

potential window, chemical inertness, simple, and fast

preparation from inexpensive materials. [1]. A large

variety of phenolic compounds exists. Some of them

may have harmful effects for the health. Their accurate

determination is of great importance due to their toxicity

and persistency in the environment, and the detrimental

effect of phenols on human health requires a strict

directive for the identification and quantification of such

compounds [2, 3]. In this study, a novel carbon paste

electrode using the salt form of polyaniline (pani)-

activated carbon composite sensitive to phenol, was prepared.


Polyphenol oxidase (tyrosinase) enzyme was

immobilized onto carbon paste electrode containing

polyaniline-activated carbon by cross-linking with

glutaraldehyde. The amperometric determination is

based on the electrochemical reduction of o-quinone

generated in the enzymatic reaction of phenol at -0.15 V

vs. Ag/AgCl. Scheme 1 shows reaction for the phenol

determination.


In this study, a novel carbon paste electrode using the

salt form of polyaniline (pani)-activated carbon

composite sensitive to phenol, was prepared. The effects

of pH and temperature were investigated and optimum

parameters were found to be 8.0 and 45 °C,

respectively. The linear working range of the electrode

was 1.0×10-6 - 5.0×10-5 M, R2 =0.982. The storage

stability and operation stability of the enzyme electrode

were also studied.

Scheme 1 Reaction scheme for the detection of phenol

References

[1] Arduini, F., Giorgio, F.Di., Amine, A., Cataldo, F.,

Moscone, D., and Palleschi, G. (2010). Electroanalytical

Characterization Of Carbon Black Nanomaterial Paste

Electrode: Development Of Highly Sensitive Tyrosinase Biosensor For Catechol Detection. Analytical Letters,

43, 1688–1702.

[2] Hervas Pérez, J.P., Sanchez-Paniagua López, E.,

López-Cabarcos, M., López-Ruiz, B. (2006)

Amperometric tyrosinase biosensor based on

polyacrylamide microgels. Biosensors and

Bioelectronics, 22, 429–439.

[3] Rogers, K.R., Becker, J.Y., Wang, J., Lu, F., (1999).

Determination of phenols in environmentally relevant

matrices with the use of liquid chromatography with an

enzyme electrode detector. Field Anal. Chem. Technol., 3(3), 161–169.



Gold Modified Anisotropic Titanium Nanorod arrays for Sensing Applications

D.Ş. Özden1*, M. Yılmaz2, E. Pişkin1, G. Demirel3

1 Department of Bioengineering Chemical Engineering Department and Bioengineering Division, Center for

Bioengineering and Biyomedtek/Nanobiyomedtek, Hacettepe University, 06800, Beytepe, Ankara, Turkey 2 Engineering and Architecture Faculty, Bioengineering Department, Sinop University, 57000, Sinop, Turkey

3 BIMREL Research Group, Department of Chemistry, Gazi University, Turkey


1. Introduction

Nanostructured titanium has become of great

importance in the development of functional materials

which could be used in photocatalysis, sensing, photovoltaics, water splitting, lithium ion batteries and

tissue engineering. Among the various oxide and non-

oxide 3-D nanostructured materials, titanium nanorods

(TiNRs) have also attracted increasing attention due to

their unique features [1]. Here, we demonstrated a

simple method to fabricate directional 3-D titanium

nanorod arrays through an oblique angle vapor

deposition approach. By combining fabricated TiNR

arrays with a thin layer of gold, they were utilized in

plasmonic catalysis and sensing applications.

2. Experimental

The glass slides or silicon wafers were first cut

(2.5x2.5 cm) and washed with deionized water, acetone,

and piranha solution consecutively. To eliminate any

contaminants, pre-cleaned surfaces were then treated

with oxygen plasma at low pressure (0.2 mbar) for 30

min before titanium deposition. The directional titanium

nanorod arrays were fabricated in a physical vapor

deposition (PVD) system (NANOVAK HV, Ankara,

Turkey) using a homemade OAD equipment. The

thickness of deposited films was monitored using an

Inficon XTM/2 deposition monitor with 0.5% sensitivity. Base pressure was gained by using a

mechanical pump (Edwards E2M2 model, up to 10-3

Torr) and a turbo pump (Turbovac 50, up to 10-6 Torr)

and monitored via a Terranova Model 934 Wide Range

Vacuum Gauge Controller. During deposition, the base

pressure was almost fixed at ~10-6 Torr with a titanium

evaporation rate of 0.1 Å s-1 [2]. The directional titanum

nanorods were created at different deposition angles to

manipulate their surface densities.


Figure 1 shows the top-view and cross-sectional SEM

images of fabricated TiNRs. It is clear that the TiNRs

are uniform and vertically aligned to the glass surface.

The length of the fabricated TiNRs were analyzed by

employing freeware ImageJ software and determined to

be 1.92 ± 0.05 µm.

Figure 1. Top-view (a) and cross-sectional (b) SEM

images of fabricated TiNRs and (c) cross-sectional

(d) top-view images of Au thin film coated TiNRs.

Gold deposition was performed in PVD as thin film

with different thickness such as 10, 20, 30 nm.

Moreover, the effect of calcination of surface modified

titanium nanorods were examined by using different

temperatures such as 300, 450, 500, 600, 750 °C [3]. Specifically, we studied the dewetting of gold films on

TiNR arrays. To investigate the SERS activity, the

raman enhancement properties were measured.

As a result, we showed the formation of titanium nanorod structures with PVD-OAD technique. Our

results indicated that the SERS activity for gold

deposited TiNRs can be manipulated through annealing

temperature.

Ackowledgement: This work was supported by Gazi

University (05/2015-19).

References

[1] Yu et al. Applied Catalysis B: Environmental, 2009,

90, 595–602. [2] Yılmaz et al. Phys. Chem. Chem. Phys., 2014, 16,

5563.

[3] Schaefer et al. Acta Materialia, 2013, 61, 7841–7848




Removal of Toxic Metals by using Janus Micromotors

D. A. Uygun1,2*, B. Jurado-Sanchez1, M. Uygun1,2 and J. Wang1

1Department of Nanoengineering, University of California, San Diego, La Jolla, CA 92093, USA

2Department of Chemistry, Adnan Menderes University, Aydın, Turkey


1. Introduction

Heavy metal pollution has been accelerated dramatically

since the industrial revolution, and is currently posing

major environmental and human health concerns. Such

widespread use has resulted in substantial accumulation

of toxic heavy metals in the environment and living

organisms. Therefore, the removal and detoxification of

metals, such as lead, cadmium, thallium, mercury, and

arsenic has attracted a considerable recent attention [1].

Advances in nanotechnology have opened new horizons

for addressing metal remediation demands due to the unique properties of nanosized materials, e.g., extremely

high surface area, high catalytic and antimicrobial

properties and tunable surface chemistry.3 Recently

developed meso-2,3-dimercaptosuccinic acid (DMSA)-

iron oxide nanoparticles display high capacity and

selectivity for softer heavy metals in water samples [2].

Here we describe high-speed metal chelation and

removal using self-propelled ligand-functionalized

water-powered micromotors. The autonomous

propulsion of synthetic micromotors through fluid

environments is one of the most exciting fields of nanotechnology [3]. The new self-propelled chelation

platforms described here are based on fuel-free Mg

Janus-micromotors, functionalized with DMSA, for

efficient removal of heavy metals from environmental

and biological media

2. Methods

The micromotors were prepared using magnesium

microparticles as the base particles and one half of

microparticles were coated with a 100 nm Ti layer and a

10 nm gold layer. External gold surface of microparticles was modified by overnight incubation of

meso-2,3-dimercaptosuccinic acid.

Zn, Cd and Pb amounts were measured

electrochemically. For this, stripping voltammetric

measurements were performed with an “in situ” co-

deposition of a bismuth film and the target metals in the

presence of dissolved oxygen

3. Results

The new micromotors were prepared by half-coating

Mg microparticles (average diameter 20 μm) with Ti

and Au layers. The scanning electron microscopy

(SEM) images of Fig. 1, reveal the spherical Janus

structure of the resulting micromotor, indicating that it

maintains its structure after the modification process.

Figure 1 SEM images showing the Janus structure

before (a) and after (b) dissolution of the Mg

core.

Fig. 2 displays the effect of the treatment time upon the

motor induced removal of Z(II), C(II) and P(II). A

dramatic decreases of the initial response of these heavy

metal ions (a), corresponding to 85% (Zn and Cd) to

99% (for Pb) removal, is observed following a 3 min

treatment with the Mg/Ti/Au/ DMSA micromotor (d).

Longer navigation times result in the complete removal

of these metal ions from the contaminated samples (e).

In contrast, no apparent change in the metal

concentration is observed in the presence of the moving

unmodified (ligand-free) micromotors.

Figure 2 Effect of the navigation time on the

removal of Zn(II), Cd(II) and Pb(II) by

Mg/Ti/Au/DMSA micromotors.

4. References

[1] F. Fu and Q. Wang, J. Environ. Manage., 2011, 92,

407.

[2] W. Yantasee, C. L. Warner, T. Sabgvanich, R. S.

Addleman,T. G. Carter, R. J. Wiacek, G. Fryxell, C.

Timchalk and M. Warner, Environ. Sci. Technol., 2007,

41, 5114. [3] J. Wang, Nanomachines: Fundamentals and

Applications, Wiley-VCH, Weinheim, Germany, 2013,

ISBN 978-3-527-33120-8.




Reliability and sensitivity of paper-based glucose sensing: comparison of sensing

mechanisms Deniz Baş1*

1 Nanobiosensing & Food Safety Research Group, Department of Food Engineering, Çankırı Karatekin University,

Çankırı, 18100, Turkey


1. Introduction

Paper-based sensing platforms are promising due to

their low-cost and easy-to-use structure [1]. The sensing

principle mostly based on colorimetric read-out. Until a

few years back, paper-based platforms/assays are only

used for qualitative measurements. By implementing

specific colorimetric reactions and the usage of

optoelectronic devices i.e. scanners, cell phones etc,

paper-based platforms became important for

quantitative sensing for point-of-care diagnostics.

Herein, two glucose sensing mechanisms were

compared and reliability and sensitivity of the methods were investigated.

2. Materials and Method

Preparation of sensing platform: Design of the patterns

was performed by opensource software Inkscape 0.91

(www.inkscape.org). Patterns were printed on the filter

papers (Sartorius Stedim, quantitative filter, particle

retention 12-15 µm). Finally, hydrophobic channels

were obtained by painting with permanent ink marker

(Edding 141F).Glucose measurements: Glucose,

glucose oxidase (GOx), peroxidase (POD), phenol,

potassium iodide (KI), 4-aminoantipyrine (4-AA) were purchased from Sigma-Aldrich (Germany). Two

different glucose sensing mechanisms (Hata! Başvuru

kaynağı bulunamadı. and Hata! Başvuru kaynağı

bulunamadı.) were used and for both mechanisms the

specific reaction between glucose and glucose oxidase

enzyme is the common step. Mechanisms differ from

each other according to the reaction of hydrogen

peroxide with the chromagens.

Scheme 1. Glucose assay based on iodine formation

Scheme 2. Glucose assay based on the quinone dye

formation

For iodine formation reaction, 300 U/ml GOx, 500 U/ml

POD and 0.6 M KI mixture and for quinone dye

formation 300 U/ml GOx, 500 U/ml POD, 1 M phenol

and 0.1 M 4-AA mixture was used as test solution. For

visual detection; 2 µl of test solution was pipetted onto

test zones and dried at room temperature. Glucose assay

was performed by pipetting 2 µl of standard glucose

solutions to the test zones. Finally, quantitative glucose

measurement was performed by the reading the L*a*b

color space values and sensitivity of the mechanisms

was investigated.


Comparison of glucose sensing strategies: As a result of

quionone dye formation mechanism, color development

is uniform when compared with iodine formation reaction (Figure 1) and the color intensity is higher.

Uniformity of color developed by quionone dye

formation increases the reliability of glucose sensing

and higher color intensity lowers the limit of detection.

Figure 1. Paper-based glucose sensing A) Quinone dye

formation B) iodine formation

Limit of detection (LOD) values for glucose were

determined as ~0.5 mM and ~1 mM for quinone and

iodine formation, respectively. LOD for quinone

method on paper platform is also lower than the LOD

value of same method performed by spectrophotometer.

The stability of the quinone dye formation mechanism

was investigated for about 40 days. For this purpose;

test solution was pipetted onto test zones and paper

platforms were stored at room temperature by avoiding

interaction with the ambient light. Test platform is

stabile for 30 days. On the other hand, iodine method is

not stabile and in almost 3 days, a drastic decrease had been observed. Moreover, results obtained by using

scanner and cell phones (Android and iosX) were

investigated and performance of platforms were

determined.

4. References

[1] A.W. Martinez, S.T. Phillips, M.J. Butte, G.M.Whitesides, Patterned

paper as a platform for inexpensive, low-volume, portable bioassays,

Angew. Chem. Int. Ed. 46 (2007) 1318–1320.


http://www.inkscape.org/


Electrochemical determination of interaction between DNA and anticancer drug

capecitabine by using DNA modified carbon paste electrodes

D. Kiziloluk1*, G. Gökçe2, Ş. Çetinus1 and A. Erdem3

1Cumhuriyet University, Faculty of Science, Department of Biochemistry, Sivas, TURKEY

2Cumhuriyet University, Faculty of Education, Department of Elementary Science, Sivas, TURKEY 3Ege University, Faculty of Pharmacy, Department of Analytical Chemistry, Izmir, TURKEY


Abstract Recently there has been an increasing attention to detect

the interaction between DNA and anticancer drugs by

using biosensor technologies 1. In this study, it was investigated that the interaction between capecitabine

which is anti cancer drug, and DNA by electrochemical

methods in combination with carbon paste electrode

(CPE). The interaction between capecitabine and the

single stranded DNA (ssDNA) and double stranded

DNA (dsDNA) obtained from calf thymus (ct dsDNA)

was investigated by monitoring the differences at the

guanine oxidation signals. The experimental parameters

such as the concentrations of ct DNA and drug, and also

the interaction time were optimized. The detection limit was estimated and the results were comprised

repeatability of carbon paste electrode. It was also

confirmed that ct DNA had immobilized onto electrode

surfaces by impedimetric measurements using

electrochemical impedance spectroscopy technique 2,

3.

Ct dsDNA and ct ssDNA were immobilized onto the

electrode surface, and accordingly the voltammograms

were recorded. It was observed that there was an

increase at the oxidation signal of guanine 4.

In the case of DNA interaction with capecitabine, there

was a decrease at guanine signal. Thus, it could be

explained as the result of interaction between DNA and

capecitabine. It was tested that interaction between capecitabine and ct dsDNA or ct ssDNA separately

using carbon paste electrode 5.

The calibration graphs were plotted between the

concentration of capecitabine and guanine oxidation

current in order to determine the detection limits. The

detection limit (DL) was estimated of carbon paste

electrode for ct ssDNA and ct dsDNA and found to be

17, 12 μg/mL and 17, 35 μg/mL respectively 6.

As a result, it is concluded that the proposed method

could be used furtherly for elucidation of the interaction

between the newly synthesized molecules and DNA.

Key Words:

Electrochemical DNA Biosensor, Capecitabine, Carbon

Paste Electrode, Differential Puls Voltammetry,

Electrochemical Impedance Spectroscopy.

Acknowledgements: This work is supported by the

Scientific Research Project Fund of Cumhuriyet

University under the project number F-387.

References

1 Wang, L., Lin, L., Ye, B. (2006). Electrochemical studies of the interaction of the anticancer herbal drug

emodin with DNA, Journal of Pharmaceutical and

Biomedical Analysis, 42: 625–629.

2 Erdem, A., Özsöz, M., (2001). Interaction of anticancer drug, Epirubicin with DNA, Analitica

Chimica Acta, 437, 107-114.

3 Wang, J., Flechhsig, G., Erdem, A., Korbut, O., Gründler, P. (2004). Label-free DNA Hybridization

based on coupling of a heated carbon paste electrode

with magnetic separations, Electroanalysis, 16 (11),

928-931.

4 Erdem, A., Özsöz, M. (2002). Review: Electrochemical DNA biosensors based on DNA-Drug

interactions, Electroanalysis, 14, 965-974.

5 Erdem, A., Özsöz, M. (2001) Voltammetry of the anticancer drug mitoxantrone and DNA, Turkish

Journal Chemistry, 25: 469- 475.

6 Palecek, E., Fojta, M., Jelen, F., Vetterl, V. (2002). Electrochemical analysis of nükleic asids, the

Encyclopedia of electrochemistry, Bioelectrochemistry,

9: 365-429.




A Highly Sensitive Nonenzymatic Ascorbic Acid Sensor Based on

Quantum Dots and Graphene Oxide

D. Söğüt1*, Z.Ö. Erdoğan1, C.Başlak1 and S. Küçükkolbaşı1

1Department of Chemistry, Faculty of Science, Selçuk University, 42075 Konya, Turkey


Abstract

Ascorbic acid (AA), water soluble vitamin, plays

important role in several life processes, such as antioxidant, nutritional factors. AA is commonly used

in food, beverages, pharmaceutical and cosmetic [1].

The detection of AA is important in food industry and

diagnostic application. Many methods have been used

for detection of AA, including spectroscopy, titrimetry,

enzymatic analysis, HPLC, electrophoresis and

electrochemical methods. Among these methods,

electrochemical method is very interesting because of

their high sensitivity, ease of monitoring, simplicity and

low cost [2].

Because of their unique chemical, physical and electronic properties, Quantum dots (QDs) and graphen

oxide (GO) are now extremely attractive and important

nanomaterials in analytical applications [3]. In this

work, CdTe QDs with the size of about 3 nm were

prepared and a novel electrochemical sensing platform

of ascorbic acid on CdTe/GO electrode was explored. In

this study, a novel, stable and sensitive non-enzymatic

AA sensor was constructed based on a glassy carbon

electrode (GC) modified with quantum dots supported

on graphene oxide (QDs -GO).

The electrochemical performance of the modified electrode for detection of AA was investigated by cyclic

voltammetry and amperometric measurements.

Electrochemical properties of different materials on the

electrode surface was characterized by cyclic

voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements in 0.10 M KCl

solution containing 50 mM Fe(CN)6 3−/4− as a redox

probe. The effect of pH, buffer concentration,

deposition potential, deposition time and scan rate were

investigated for modified electrode.

Compared to a bare GC the modified electrode

exhibited a rapid response to AA and the amperometric

signal showed a good linear correlation to AA

concentration in a broad range from 32.5-500 µM with a

correlation coefficient of R = 0.9991. Moreover, the

proposed sensor was applied to the determination of AA

in in fresh fruit juice samples. The satisfactory results

obtained indicated that the proposed sensor was

promising for the development of novel electrochemical

sensing for AA determination.

Figure 1. Amperometric response of

CdTe/GO/GCE.

References

[1] Liu, J.J., Chen, Z.T., Tang, D.S., Wang, Y.B.,

Kang, . L.T., Yao, J. N., Sensors and Actuators B,

212 (2015) 214-219.

[2] Liu, B., Luo, L., Ding, Y., Si, X., Wei, Y., Ouyang,

X., Xu, D., Electrochimica Acta, 142 8 (2014) 336-

342

[3] Zhao, J., Chen G., Zhu L., Li G., Electrochemistry

Communications, 13 (2011) 31–33.




Application of SWCNT and poly(3-methylthiophene) modified sensors for

simultaneous determination of levodopa and benserazide

Ebru Kuyumcu Savan

1* and Gamze Erdoğdu

2

1Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, İnönü University, Malatya, Turkey 2Department of Chemistry, Faculty of Science, İnönü University, Malatya, Turkey


1. Introduction

Levedopa (L-Dopa) and Benserazide are a significant

neurotransmitters because of its role in the functioning

of the cardiovascular, renal and central nervous system.

It is important to detect L-Dopa and Benserazide using a

reliable method with good sensitivity and selectivity.

Due to the electrochemically oxidizable characteristic,

there has long been a great deal of developments in

electrochemical determination of L-Dopa and

Benserazide [1-3]. The coexistence of L-Dopa and

Benserazide and other reductants such as ascorbic acid with very close oxidation potentials leads to interference

in voltammetric response. The anodic potentials of AA,

L-Dopa and Benserazide at unmodified sensors always

overlap with each other, which is the major problem in

their simultaneous determination by electroanalytical

methods [4,5]. Therefore, improvement of the

sensitivity and selectivity of the sensor towards L-Dopa

and Benserazide has been a longstanding issue of

researchers. To overcome this problem, a glassy carbon

electrode was modified with electropolymerized film of

3-methylthiophene and single-walled carbon nanotube.

2. Experimental

Instrumentation

All the electrochemical operations (Cyclic voltammetry

(CV) and Differential pulse voltammetry (DPV) were

carried out by a BAS (Bioanalytical Systems, Inc.) 100

W electrochemical analyzer. The three electrode system

consisting of a glassy carbon disc working electrode

(geometric area: 6.85 mm2, CHI), an nonaqueous

Ag/Ag+ reference electrode (CHI112) and a Pt wire coil

auxiliary electrode (CHI) was used.

Preparation of modified sensor

Conducting polymer coating on the GCE was achieved in a three-electrode single-compartment cell containing

150 mM 3-methylthiophene (3-MT) and 100 mM

TBATFB (as electrolyte) dissolved in acetonitrile. The

polymer film was grown on GCE by CV from (-200) to

(+2000) mV at 50 mV/s for 14 cycle. N,N-

dimethylformamide (DMF) dispersions of the single-

walled carbon nanotubes (SWCNT) were prepared at

different concentrations, 0.2%, 0.5%, 1.0% (mg/μL).

Modified sensors while acquiring, 3-MT films, are

coated above and below of the SWCNT-COOH on the

GCE surface. For this purpose, different volumes (10,

20 µL) of SWCNT/DMF dispersions were added dropwise on poly (3-MT) film or bare GC electrode and

dried at room temperature for 1 day.


Determination of Levedopa and Benserazide

Figure 1. DPV results of 1.0 mM LD ve 1.0 mM BS on a)11.; b)12.;

c)13.; d)14.; e)15.; f)16. modified sensors

Interference study

Figure 2. DPVs for a mixture of 1.0 mM LD, 0.1 mM BS and 5.0 mM

AA at modified sensor in pH 7.0 PBS.

4. Conclusion

The modified sensor has been used for investigation of

the dermination of Levedopa and Benserazide in the presence of AA. The modified sensor has an excellent

response and specificity for the electrocatalytic

oxidation of Levedopa and Benserazide in PBS (pH

7.0). Linear calibration curves for DPV analysis were

obtained. By obtaining very low LOD, Levedopa

(1.77x10-5 M) and Benserazide (9.7x10-5 M) can be

determined simultaneously in the presence of interfence

such as AA.

References

[1] Anal. Chem. 73, (2001), 1196. [2] Anal. Chem. 71, (1999), 1055.

[3] J. Braz. Chem. Soc. 21(8), (2010), 1572.

[4] J. Electroanal. Chem. 561, (2004), 173.

[5] Anal. Chem. 68, (1996), 2084.




Simultaneous determination of levodopa and carbidopa in the presence of

ascorbic acid using nanostructured electrochemical sensor based on 3-

methylthiophene and MWCNT

Ebru Kuyumcu Savan1* and Gamze Erdoğdu2

1Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, İnönü University, Malatya, Turkey

2Department of Chemistry, Faculty of Science, İnönü University, Malatya, Turkey


1. Introduction

Parkinson’s disease is believed to be related to low levels of the neurotransmitter dopamine in the brain. Therefore, the dopamine precursor levodopa is employed for its treatment. For better therapeutic effect and lower toxicity, carbidopa is administered in association with levodopa in pharmaceutical

formulation containing 10–25% of carbidopa [1]. For simultaneous determination of levodopa and carbidopa a glassy carbon electrode was modified with electropolymerized film of 3-methylthiophene (3-MT) and multi-walled carbon nanotube. Utilizing the developed method, determination of the two compounds has been carried out in pharmaceutical formulations, water and urine samples.

2. Experimental

All the electrochemical operations were carried out by a BAS

100 W electrochemical analyzer with three electrode system. Conducting polymer coating on the GCE was achieved containing 150 mM 3-MT and 100 mM TBATFB (as electrolyte) dissolved in acetonitrile by CV. Modified sensors while acquiring, poly(3-MT) films, are coated above and below of the MWCNT-COOH on the GCE surface.


Simultaneous determination ol LD and CD

Fig.1. DPV results of 1.0 mM LD ve 0.1 mM CD on a)1.; b)12.; c)13.;

d)14.; e)15.; f)16. modified sensors

Fig.2. DPVs for a mixture of 1.0-5.0 mM LD, 0.1 mM CD and 5.0 mM

AA at modified sensor in pH 7.0 PBS.

Fig.3. DPVs for a mixture of 1.0 mM LD, 0.1 mM CD and 5.0 mM AA

at modified sensor in pH 7.0 PBS.

Table 1. Electrochemical determination of LD and CD in Sinemet

tablet Tablet (mg) Found (mg) Recovery%

Sample LD CD LD CD LD CD

1 2.262 0.226 2.448 0.229 108.2 101.4

2 2.262 0.226 2.092 0.216 92.49 95.51

3 2.262 0.226 2.078 0.230 91.85 101.4

4 2.262 0.226 2.238 0.224 98.94 99.16

5 2.262 0.226 1.897 0.228 83.86 100.6

Mean 95.06 99.60

SD 8.12 2.20

RSD% 8.54 2.21

RE% 4.94 0.40

4. Conclusion

The modified sensor has an excellent response and specificity for the electrocatalytic oxidation of Levedopa and Carbidopa.

References

[1] Bioelectrochemistry. 93, (2013), 15–22.




An investigation of the effect of 2,4-dithio-phenoxy-1-iodo-4-bromo benzene

molecule on rat liver and kidney tissue

Eda Çınar Avar1*, Elif Loğoğlu1 and Şule Coşkun Cevher2

1Gazi University, Faculty of Sciences, Department of Chemical, Ankara, Turkey 2Gazi University, Faculty of Sciences, Department of Biology, Ankara, Turkey


1. Introduction

Nowadays fungal infections, tuberculosis, cancer and

AIDS have become the main cause and the most

important complexities of death and/or morbidity for the people who had an organ transplant and their immune

system depressed (1,2). Triazole antifungal compounds

like fluconazole and voriconazole function inhibiting

the lanosterol cytochrome P450 14α-demethylase

(CYP51) enzyme. However, clinical values, relatively

high toxicity, the emerge of drug resistance and

pharmacokinetic shortcomings of these compounds are

limited because of their lack of antifungal activities.

Broad spectrum antifungal agents with low toxicities are

still needed in despite of the recent developments (3,4).

In this sense the antifungal and antibacterial effects of

the newly synthesized thio halo-benzene derivative 2,4-dithio-phenoxy-1-iodo-4-bromo benzene have been

revealed in previous studies. This compound has similar

carbon structure with commonly used antifungal drug

fluconazole, not to mention that it is more active than

low concentrations of fluconazole.

2. Methods

In this study, effects of previously proved as an

antibacterial and antifungal molecule 2,4-dithio-

phenoxy-1-iodo-4-bromo benzene (C18H12S2IBr) on

mammal liver tissue and mammal kidney using

biochemical methods. 30 adult Wistar albino rats between the range of 150-200 gr have been used for this

study. Total 6 female rats have been used as subjects in

this experiment. Rats have been given fluconazole as

well as 2,4-dithio-phenoxy-1-iodo-4-bromo benzene

orally, each dissolved in alcohol, once in a week for 4

weeks. All subjects separated into 5 groups: a control

group, alcohol control, fluconazole group (0.28 mgr/100

gr) and two different doses of 2,4-dithio-phenoxy-1-

iodo-4-bromo benzene (0.112 mg/100 gr and 0.056

mg/100 gr).

3. Results and discussion

When 2,4-dithio-phenoxy-1-iodo-4-bromo benzene

molecule and fluconazole compared, it is shown that

2,4-dithio-phenoxy-1-iodo-4-bromo benzene does not

cause any oxidative damage on liver tissue particularly

on female rats, in fact it is even acts like an antioxidant

because of its low MDA levels (lower than control

group).

Table 1. Results from female rat liver MDA, GSH, AA,

NO levels and MPO activity

MDA

(nmol/g tissue)

GSH

(nmol/g tissue)

AA

(nmol/g tissue)

MPO

(nmol/g tissue)

NOX

(nmol/g tissue)

Group 1 122.8±28.8a

22.7±4.6a

3.5±0.2a

0.7±0.10a

436.7±18.2a

Group 2 135.3±17.3b

28.4±4.2b

- 0.7±0.08b

426.8±36.2b

Group 3 77.2±4.1c

19.3±1.6c

- 0.4±0.02c

477.7±16.7c

Group 4 57.5±4.5d

18.8±1.9d

2.9±0.2d

0.4±0.02d

450.2±9.4d

Group 5 48.6±7.7e

18.9±1.2e

2.7±0.4e

0.4±0.02e

426.3±15.0e

For MDA levels : a-c, a-d, a-e, b-c, b-d, b-e, c-e p< 0.05

For GSH levels : a-c, a-d, a-e, b-c, b-d, b-e p< 0.05

For AA levels: a-d, a-e p< 0.05

For MPO activity: a-c, a-d, a-e, b-c, b-d, b-e p< 0.05

For NOx levels: a-c, b-c, c-d, c-e , d-e p< 0.05

The effects of this two molecule -fluconazole and newly synthesized antifungal and antibacterial 2,4-

dithiophenoxy-1-iodo-4-bromo benzene on mammal

tissues examined on both male and female rat liver and

kidney tissues. This effects on mammal tissues

examined as liver and kidney MDA, GSH, AA, NO

levels and MPO activity. Liver MDA, GSH, NO, AA

levels and MPO activity of female rats have been given

in Table 1. These two new antioxidants considered to

be used to eliminate the free radicals in the chemical

metabolism when GSH and AA levels from all groups

are compared. Changes in MPO activity indicates that

2,4-dithio-phenoxy-1-iodo-4-bromo benzene molecule doesn’t contribute to neutrophil infiltration as well as

fluconazole. It is concluded that this newly synthesized

antifungal compound does not cause any oxidative

damage in kidney tissue, especially on males.

References

[1] S.K. Fridkin and W.R. Jarvis, Clin. Microbiol. Rev. 9 (1996), pp. 499–511.

[2] J.R. Wingard and H. Leather, Biol. Blood Marrow Transplant. 10 (2004), pp.

73–90.

[3] P. Kale and L.B. Johnson, Drugs Today 41 (2005), pp. 91–105.

[4] S. Sundriyal, R.K. Sharma and R. Jain, Curr. Med. Chem. 13 (2006), pp.

1321–1335.



The Effect of the para and meta Positions in Immobilized New Supports

for Determination Phosmate

E. Hasanoğlu Özkan1*, N. Kurnaz Yetim1,2, N. Sarı1 and A. Dişli1

1 Department of Chemistry, Gazi University, Ankara, Turkey

2 Department of Chemistry, Kırklareli University, Kırklareli, Turkey


1. Introduction

As is known, enzyme is immobilization by interactions

between the support and the enzyme such as covalent

bonding, hydrogen bonding and Van Der Waals forces

[10]. If a polymer-based nano-sphere supports have

electronegative groups like Oxygen, nitrogen and

fluorine may be useful for increasing the enzyme

stability via hydrogen bonding attachment [11]. So, the

surface on which the enzyme is immobilized has several

vital roles to play such as retaining of tertiary structure

in the enzyme through hydrogen bonding. Acetylcholinesterase (AChE) is crucial enzyme in the

central nervous system of living organisms [12]. The

inhibition of AChE activity by organophosphorus (OP)

compound is an irreversible process. In this process,

AChE is inactivated. OP compounds, commonly used as

insecticides [13]. AChE is a serine protease enzyme.

The inhibition of AChE catalytic activity by OP is

caused due to phosphorylation of serine residue [14].

2. Experimental

a. Immobilization of AChE on nanomaterial

(2AEPS-(m/p-F-Tet-1H)

After dissolving enzyme in pure water (50 mL, 3.6 x 10-4 gL-1), 2AEPS-(m-F-Tet-1H) and (AEPS-(p-F-Tet-

1H) polymers (0.5 g) were placed to a 2 mL of 3.6 x 10-

4 gL-1 of AChE. This solution was diluted to 10 ml and

at room temperature in a shaking water bath for 8 h. The

immobilized polymers were separated and the free

enzyme was removed by washing with phosphate buffer

and then stored at + 4 °C. Saturation ratio was

determined as 97.60 % and 93.70 % for 2AEPS-(m-F-

Tet-1H) and 2AEPS-(p-F-Tet-1H) respectively, from

absorbance value in 412 nm.

b. Study on phosmate insecticide

N-(Mercaptomethyl) phthalimide S-(O,O-dimethyl

phosphorodithioate) was dissolved in Acetonitryl:H2O

(1.37 x 10-7 mol/L; 1:4, v/v) and its solutions were

prepared in between 10 μL - 50 μL. The absorbance

changes at 412 nm was taken into account for studied

phosmate solutions.

3. Conclusion

The first time has been presented in this study, ligated

new tetrazole derivatives on sphere have been

synthesized for the identification of organophosphates.

AChE immobilization has been successfully fabricated

for the detection of pesticide. Even for this reason, in

pesticide determination of 2AEPS-(p-F-Tet-1H)-AChE

and 2AEPS-(m-F-Tet-1H)-AChE have made more

easily interact with phosmet insecticide. The apparent

pesticide effect of the immobilized supports were

compared, and this showed that the 2AEPS-(p-F-Tet-

1H)-AChE was higher than 2AEPS-(m-F-Tet-1H)-

AChE. Probably, stereo chemical structure of 2AEPS-

(p-F-Tet-1H)-AChE has been protected the three-

dimensional structure of the enzyme by means of

hydrogen bonds.

Figure 1 Hydrogen bonds in between enzyme and

support material and photography related with

phosmet insecticide

References

[1] Beatriz M. Brena and Francisco, Batista-Viera,

Methods in Biotechnology: Immobilization of Enzymes

and Cells, Second Edition Edited by: J. M. Guisan ©

Humana Press Inc., Totowa, NJ.

[2] Hasanoğlu Özkan E, Kurnaz Yetim N, Tümtürk H,

Sarı N (2015) Dalton Trans 44: 16865-16872

[3] Periasamy AP, Umasankar Y, Chen SM (2009) A

Review,Sensors 9: 4034-4055

[4] Buckley NA, Roberts D, Eddleston M (2004) BMJ

329:1231

[5] Warner J, Andreescu S (2016) Talanta 146:79–284



An ultra-sensitive PtNPs@Graphene/Nafion electrochemical sensing-platform

for detection of silodosin in human plasma

E. Er1*, H. Çelikkan

2 and N. Erk

1

1 Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara, Turkey

2 Department of Chemistry, Faculty of Science, Gazi University, Ankara, Turkey


1. Introduction

The enlargement of the prostate gland is common in men with an increasing percentage at least 50% of men

aged over 50 years have histological evidence of benign

prostatic hyperplasia (BPH). Silodosin (SIL), α1-

adrenoreceptor antagonist in alpha-blockers class, is a

novel therapeutic agent for the treatment of the signs

and symptoms of BPH. It relieves the muscles of the

urinary bladder and prostate tract by selectively

affecting the symptoms of BPH. The recommended

dosage of SIL to relieve is 8 mg per day as it indicates

the best selectivity at this dosage [1–2]. Therefore, the

determination of SIL at low-level has a great importance especially in real samples [3]. In this point, we

proposed a novel electrochemical nano-platform based

on Platinum nanoparticles supported graphene/nafion

(PtNPs@GRP/NFN) nanocomposite material for the

electrochemical sensing of SIL using adsorptive

stripping differential pulse voltammetry (AdsDPV).

2. Experimental

Platinum nanoparticles/graphene (PtNPs@GRP) nanocomposite was produced from graphene oxide

(GO) via single-step reduction method (Figure 1) [4-5].

The formation of PtNPs@GRP was confirmed by x-ray

diffraction (XRD) and Transmission electron

microscopy (TEM).

Figure 1. Schematic presentation of the preparation

process of PtNPs@graphene nanocomposites

For the fabrication of proposed sensor, PtNPs@GRP

solution containing NFN (0.25%, v/v) was prepared to

constitute the PtNPs@GRP/NFN nanocomposite, and

followed by the modification of glassy carbon electrode

(GCE) surface with PtNPs@GRP/NFN nanocomposite.

A well-defined and irreversible oxidation peak at 714

mV was observed on the surface of PtNPs@GRP/NFN modified electrode using AdsDPV. Under optimized

conditions, PtNPs@GRP/NFN sensor exhibited an

excellent analytical performance in the detection of SIL

at nano-molar levels. The linear concentration range for

SIL was found to be 1.0-290 nM with a lower detection

limit at sub-nanomolar level.

3. Conclusion

Herein, we report a fabrication of new-generation

graphene-based electrochemical sensing platform for

the detection of SIL in human plasma. PtNPs@GRP

was effectively synthesized from GO and platinum salt using a single-step chemical reduction process.

PtNPs@GRP/NFN sensor exhibited an extraordinary

analytical performance owing to its owing to its unique

physical and chemical properties such as high surface

area, unique electrical conductivity, excellent

electrocatalytic and electrochemical activity. In

addition, proposed sensor enable to detect the SIL at

nano-molar level. It is concluded that

PtNPs@GRP/NFN sensor is a promising

electrochemical sensing-platform for the determination

of SIL in real samples.

References

[1] M. Yoshida, Y. Homma, K. Kawabe, Exp. Opin. on

Invest. Drugs 16 (2007) 1955.

[2] X. Zhao, Y. Liu, J. Xu, D. Zhang, et al., J.

Chromatogr. B 877 (2009) 3724.

[3] E. Er, H. Çelikkan, N. Erk, M.L. Aksu, Electrochim.

Acta 157 (2015) 252–257.

[4] W.S. Hummers, R.E. Offeman, J. Am. Chem. Soc.

80 (1958) 1339.

[5] T.Q. Xu, Q.L. Zhang, J.N. Zheng, et al.,

Electrochim. Acta 115(2014) 109–115.



Use of Bacterial Cellulose Membrane in the Removal of Azo Dyes

E.P. Çoban1*, U.C. Sağlam1, H. H. Biyik1

1 Department of Biology, Adnan Menderes University, Aydın, Turkey

*Presenter:[email protected]

1. Introduction

The use of dye materials is widely known in textile, plastic and paper industries [1]. The mixture of dye substances with natural water disrupts the ecological balance of water and its chemical content has a negative effect on living things. The preferred method of removing of dyes is the use of activated carbon. Although the method is effective, regeneration and reuse is a disadvantage due to cost and decrease in activity [2]. For this reason, Bacterial cellulose; a low-cost, easy to obtain and simple, with a fine reticulated pore structure and flexible

absorbent material, has been intended as an alternative. For this purpose, bacterial cellulose synthesized by Gluconacetobacter hansenii HE1 bacteria is being researched for its removal effects of Azo dye such as Aniline Blue, a widely used dye in textile.

2. Material and Method Material The Aniline Blue dye (CAS No. 66687-07-8, Sigma). Gluconacetobacter hansenii HE1 strain used in this study was provided from Adnan Menderes University Microbiology Laboratory stock cultures.

Production and purification of cellulose G. hansenii HE1 strain was inoculated in HS (Hestrin-

Schramm) (2% glucose, 0.5% yeast extract, 0.5% polypeptone, 0.675% Na2HPO4, 0.115% citric acid) broth and was allowed to produce cellulose after an incubation period of 10 days at 300C [3]. 4% NaOH and 6% acetic acid solutions were used for purification and dried by lyophilisation [4].

Dye removal Batch adsorption assay was carried out by shaking.50 mL of aniline blue solution was prepared at different concentrations (50,100 and 200 mg/L).1g of dried bacterial cellulose was added to the solutions and the solutions pH was set to a pH of 7 by using 1.0 N HCl and 1.0 N NaOH. It was kept on shaker

at 120 rpm at 280C. After, a period of 10 minutes and spectrophotometric readings were taken at 585 nm. In addition pH reading was made to observe pH changes. 50 mL of Aniline Blue (50 mg/L) was used as a positive control, 50 ml of distilled water containing cellulose was used as a negative control [1].

3. Results and Discussion Initial spectrophotometric measurements were found to be 0.3325 at 50 mg/L; 0.4116 at 100 mg/L and 1.4300 at 200 mg/L. While measurements made at 10 minute intervals showed a fading in colour, a spectrophotometric measurement

after 60 minutes were 0.0659; 0.1057 and 0.2026 respectively. Despite the solution`s starting pH of 7, as the colour fade the pH became alkaline. After 60 minutes pH observed were 8.9, 8.8, and 8.7 respectively. While the positive control containing Aniline blue solution had a pH of 8.7 and a spectrophotometric reading of 2.3868, negative containing bacterial cellulose and distilled water showed a spectrophotometric reading of 0.0336 and a pH of 7.2.

Figure 1 The initial image at different concentrations

of aniline blue dye

Table 1 Effect of bacterial cellulose on Aniline blue removal at 585 nm

Removal of dyes with bacteria cellulose at 200 mg/L solution yielded much better results than other concentrations. The results show that bacterial cellulose with a loose network, porous and nanofibril properties can be used in the removal of dyes.

Acknowledgements: This research was supported by supported TUBITAK BIDEP-2209. Project Number: 1919B011501637.

References [1] Pansar PS, Chavan YV, Bera MB, Chand O, Kumar H. Evaluation

of Acetobacter strain for the production of microbial cellulose. Asian J. Chem. 2009; 10:99–102.

[2] Bhavna VM, Satish VP. Bacterial cellulose of Gluconoacetobacter

hansenii as a potential bioadsorption agent for its green environment

applications. J. Biomat. Sci. 2014; 25(18):2053-2065.

[3]. Hestrin S, Schramm M. Synthesis of cellulose by Acetobacter

xylinum preparation of freeze dried cells capable of polymerizing

glucose to cellulose. Biochem J. 1954; 58(2):345-352.

[4]. Hyun JY, Mahanty B, Kim CG. Utilization of makgeolli sludge

filtrate (MSF) as low-cost substrate for bacterial cellulose production

by Gluconacetobacter xylinus. Appl Biochem Biotechnol.

2014;172(8):3748–60.

Figure 2 60 minutes after

the initial image at different

concentrations of aniline

blue dye



Vapor-Phase Deposition of Polymers Asa Simple and Versatile Technique to

Generate Paper-Based Microfluidic Platforms for Bioassay Applications

E. Babur1* and G. Demirel1

1 Department of Chemistry, Gazi University, Ankara, Turkey


1. Introduction

Paper-based sensor platforms having patterned fluidic

channels have a great potential in food, environment,

and health areas. Furthermore, paper-based materials

constitute suitable platforms in terms of easy

attainability and processability. Especially paper-based

sensor platforms’ replacing the conventional diagnostic

kits dependent on electronic gadgets can be estimated to

be popular considering both the cost and user-friendly

usage. However, certain difficulties have already being

seen on the issues of sample flow control, decreasing

the limit of detection, and repeatability in the paper-based sensor platforms. Especially various difficulties

have been encountered in the formation and application

of hydrophobic barriers on the hydrophilic paper to

provide a suitable flow [1,2]. In this study, we

demonstrate an alternative approach to fabricate paper-

based sensor platforms through a vapor-phase polymer

deposition technique. Furthermore, analysis of certain

target molecules such as glucose, protein, ALP, ALT and

uric acid are displayed using fabricated platforms.

2. Experimental

The conformal coating of poly(chloro-p-xylene) [PPX] films on paper samples (Whatman no. 1

chromatography paper) were performed using a SCS-

PDS2010 deposition system. A hydrophobic dichloro-

[2.2]-paracyclophane molecule was used in the

deposition process as a starting monomer. The polymer

deposition process was started by placing proper

amounts of monomer (0.01 g – 2.0 g) into evacuated

sublimator chamber. These monomers were then

evaporated at ~175 °C and converted to radicalic

monomers by pyrolysis (~695 °C). They were

subsequently deposited and polymerized onto paper samples. All process was carried out under vacuum

condition (32 mTorr). The corresponding PPX thickness

on paper samples was controlled through the amount of

the loaded monomer. The hydrophilic channels on paper

samples, which allow to transport the analyte solutions

via capillary penetration, were created using a metal

mask with desired pattern. The paper samples were

sandwiched between metal masks and magnets [3].

Figure 1 Schematic representation of the fabrication process of polymer deposition on a paper substrate

[inset: polymerization mechanism of PPX] (a),

sandwich array for patterning of the paper (b) and

colored water droplets on polymer deposited paper (c).

3. Results

We have demonstrated a technique for fabrication of paper-based sensor platforms through vapor phase

polymer deposition approach. The fabricated paper

platforms were successfully utilized for the detection of

varying biological target molecules including glucose,

protein, ALP, ALT, and uric acid. Given its

environmental friendly, solvent-free, and material

independent nature of vapor phase polymerization

method may offer new possibilities in the field of

biosensor applications.

Acknowledgements: This work was supported by the

TUBITAK (Grant 112T560) and Gazi University

(05/2015-19). Authors would like to thank Hakan Erdogan for useful discussions.

4. References

[1] E. Carrilho, A. W. Martinez and G. M. Whitesides,

Anal. Chem., 2009, 81, 7091–7095.

[2] A. W. Martinez, S. T. Phillips and G. M.

Whitesides, Anal. Chem., 2010, 82, 3–10.

[3] G. Demirel and E. Babur, Analyst, 2014, 139, 2326-

2331.



Sensing Studies of a Amine Functionalized Calixarene Derivative Coated QCM

Biosensor in Aqueous Solution

F. Temel1*, E. Ozcelik1, M. Akpinar1 and M. Tabakci1

1 Department of Chemical Engineering, Selçuk University, Konya, Turkey


Abstract

Biosensors are device which have properties of biological sensing to use for controlling and sensing of

biologic analytes. In biosensor applications, there are

several methods which are electrochemical,

calorimetric, optical and acoustic systems for

determination and sensing biologic analyte-biochemical

interaction [1].

Quartz Crystal Microbalance (QCM) is a sensor device which is simple, ease of use, low cost, shorter analysis

time for detection. During detection, mass accumulation

occurs on quartz surface and this causes frequency shift. QCM device can be used many application like antigen–

antibody, enzyme-substrate interaction, drug carrier,

volatile organic compounds detection [2]. Relationship

between frequency and mass change in liquid contact

measurement can be expressed Sauerbrey equation

2

02

Am f C f

f

(1)

where ∆m is mass change on sensor surface, ∆f is

frequency shift, ρ is density of quartz, µ is shear

modulus of quartz, A= active area of quartz and f0 is fundamental frequency of the of QCM crystal.

Calixarenes, are macrocyclic molecules which have unique three–dimensional structure and unlimited

derivatization potential. They can be synthesized by

condensation of p-tert-butylphenol with formaldehyde.

Calixarenes can be used for sensing applications [4].

Figure 2 Amine Functionalized Calix[4]arene

derivative

There are limited numbers studies about

macromolecules as biochemical sensors even though

there are many studies about polymeric materials. In

macromolecules, there are few studies about calixarenes

as biochemical material. Synthesis and derivatization of

calixarenes which can be easily detected desired

biological analyte and easily preparation of their films

on QCM crystals show that calixarenes can be used to detect biological analytes widely. In our previous

works, we have also synthesized some calixarene

compounds and they has been investigated their sensing

properties for volatile organic compounds. In this study,

we have prepared a calixarene derivative, its sensor

films and investigated its sensing abilities for bioanalyte

by calixarene-coated QCM system.

1. References

[1] Corcuera, J. I. R. D., Cavalieri, R. P., 2003

“Biosensor” , Encyclopedia of Agricultural, Food, and

Biological Engineering, 119 – 123.

[2] Lucklum, R., Hauptmann, P., 2006, “Acoustic

microsensors – the challenge behind microgravimetry”,

Anal. Bioanal. Chem., 384, 667 – 682.

[3] Sauerbrey, G., 1959, “The use of quartz oscillators for weighing thin layers and for micro-weighing”, Z.

Phys. 155, 206–222.

[4] Temel, F., Tabakci, M., 2016, “Calix[4]arene coated

QCM sensors for detection of VOC emissions:

Methylene chloride sensing studies”, Talanta, 153, 221

– 227.



Detection of Escherichia coli using Quartz Crystal Microbalance Sensor:

A Study Design

Mehmet Çağrı Soylu1, Fatma Betül Köşker1* and Keziban Canıkara1

1 Department of Biomedical Engineering, Erciyes University, Erciyes, Turkey


1. Introduction

Escherichia coli (E. coli), a natural member of human

intestinal microbiota, is one of the leading

microorganism some strains of which is a cause of

foodborne or waterborne diseases via fecal

contamination [1].

In this study, rapid, simple and sensitive genetic

detection of non-pathogenic E. coli K-12 MG1655

strain has been aimed without the need of DNA

isolation, purification and amplification.


All the probe oligonucleotides, reagents and E. coli K-

12 MG1655 strain (ATCC 47076) will be obtained

commercially and the bacteria will be cultured.

Phosphate buffered saline (PBS) will be used for

dilution. The ssDNA will be designed based on the

chosen conserved gene region (i.e. uidA gene). The

ssDNA probe will be modified at 5’ end with C6-SH. A

synthetic target DNA with complementary sequence of

probe DNA will be used for detection. The sensor

specificity will be determined using an oligonucleotide

with the same sequence of probe DNA.

The experimental design is shown in Figure 1 and the main stages of the detection procedure are:

I. Surface modification with 3-

Mercaptopropyltrimethoxysilane (MPS) for

electrical insulation [2],

II. Immobilization of the ssDNA probe,

III. Blocking with Bovine Serum Albumin (BSA) to

prevent adsorption on sensor surface,

IV. Extracting E. coli DNA with high temperature

(97 ºC) and detergent,

V. Driving the solution including target DNA via

peristaltic pump, VI. Analyzing the frequency change with impedance

analyzer,

VII. Examining the surface morphology via scanning

electron microscopy (SEM).

The stages are illustrated in Figure 2. Concentration of E. coli, the amount of BSA and detergent, flow rate,

immobilization, Signal-to-noise ratio (SNR) and signal

matching algorithm will be optimized during the

experiments.

Figure 1. Experimental design

SNR must be above 3. The target level of detection is

determined as 1010 copy/ml which is expected to be

increased using microspheres to 105 copy/ml.

3. Results

The designed and optimised system for non-

pathogenic E. coli will be used for detection of

pathogenic and toxigenic E. coli strains at the next

level.

References

[1] Lee, H., et al., Rate and molecular spectrum of

spontaneous mutations in the bacterium

Escherichia coli as determined by whole-genome

sequencing. Proceedings of the National

Academy of Sciences, 2012. 109(41): p. E2774-

E2783.

[2] Soylu, M.C., W.-H. Shih, and W.Y. Shih, Insulation by Solution 3-Mercaptopropyltrimethoxysilane

(MPS) Coating: Effect of pH, Water, and MPS

Content. Industrial & Engineering Chemistry

Research, 2013. 52(7): p. 2590-2597.

Figure 3. Study design and detection procedure



A new sensitive electrochemical method for simultaneous determination of

amlodipine and telmisartan drug

F. Kartal1*, N. K. Bakirhan1 and S. A. Ozkan1

1 Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara, Turkey


1. Introduction

Twynsta is used to treat high blood pressure

(hypertension). Lowering blood pressure may lower

your risk of a stroke or heart attack. Twynsta contains a

combination of amlodipine (AML) and telmisartan

(TLM). AML is a calcium channel blocker. AML

relaxes (widens) blood vessels and improves blood flow.

TLM is an angiotensin II receptor antagonist. TLM

keeps blood vessels from narrowing, which lowers

blood pressure and improves blood flow.

Up to date, AML and TLM compounds have been

studied with spectrophotometry, liquid chromatography.

However, there is no information about simultaneous

determination of these two compound with

electrochemical methods. And also, there is no

quantitative developed method has been proposed for its

analysis in dosage forms by electrochemical method.

2. Experimental

In this work the voltammetric behavior of AML and

TLM disodium was studied at a glassy carbon. The aim of this work is to carry out a detailed investigation on

the electrochemical behavior and possible oxidation

mechanism of AML and TLM disodium by using cyclic,

differential pulse, and square wave voltammetric

techniques. For this purpose, AML and TLM were

studied in various supporting electrolyte including

H2SO4, phosphate, acetate and Britton-Robinson buffers

(pH values between 0.3–10.0) containing 10%

methanol. The scan rate studies were realized in 0.5 M

H2SO4 solution for glassy carbon electrode,

understanding the mass transfer process to the electrode

surface. When the scan rate was varied from 5 to 750 mVs−1 in 1×10−4 M AML and TLM disodium solution, a

linear dependence (r≥0.999) of the peak intensity Ipa

(µA) upon the scan rate (mV.s−1) was found for a glassy carbon electrode, demonstrating an adsorption

process.

3. Results & Discussion

Voltammetric method exhibited linear dynamic

responses for simultaneous assay of AML and TLM in

the concentration range between 1.0×10-7 M – 1×10-4 M

and 1.0×10-7

M – 1.0×10-5

M, with detection limits of

0.654 nM and 22.6 nM, respectively.

AML

Figure 1. TLM

4. Conclusion

Simple, selective, sensitive, fully validated, rapid, and reliable adsorptive stripping square wave voltammetry

methods were applied for the simultaneous analysis of

AML and TLM in pharmaceutical dosage form,

Twynsta. Precision and accuracy of developed method

was checked by recovery studies. These techniques did

not require sample pre-treatment or any time-consuming

extraction step prior to drug assay in dosage forms.



A novel electroanalytical nanosensor based on AgNPs nanoparticles for

determination of antiviral drug tenofovir

G. Ozcelikay1*, B. Dogan-Topal1 and S.A. Ozkan1

1Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, 06100 Ankara, Turkey


1. Introduction

Tenofovir Disoproksil Fumarat (TEN) is an antiviral

drug active compound which is used for the treatment of

the AIDS. The voltammetric oxidation of TEN was

investigated at silver nanoparticles modified glassy

carbon electrode using cyclic (CV), Osteryoung Square

Wave Stripping (OSWSV) Voltammetry over a wide

pH range.

For the analytical application, operational parameters

have been optimized. The dependence of intensities of

currents and potential on pH, concentration, scan rate,

nature of the buffer was investigated.

2. Methods

a. Reagents and Apparatus

A stock solution of 1.0x10-3 M was prepared by

dissolving the compound in bidistilled water. Standard

solutions were prepared by serial dilution of the stock

solution with selected supporting electrolyte.

The CV and OSWSV experiments were performed

using a BAS 100W electrochemical analyzer. The

utilized electrodes were: silver nanoparticles modified

glassy carbon as a working electrode; a platinum wire as

a counter electrode and an Ag/AgCl (BAS; 3M KCl) as a reference electrode.

OSWSV conditions: pulse amplitude, 35 mV;

frequency, 30 Hz; potential step 8 mV. The parameters

of stripping methods were also optimized.

AgNP amount was investigated for the well-defined

peak shape and peak current. 5.0–15.0 µL AgNP

suspensions were dropped on GCE surface. The

optimum result was obtained with 10.0 µL AgNP

suspensions in pH 5.7 acetate buffer.

b. Analysis of tablets

A weighed portion of the powder content equivalent to

1x10-3M of tenofovir was transferred into a 50mL-calibrated flask and completed to the volume with

bidistilled water.


No previous electrochemical studies were available the

sensitive anodic electroanalytical determination of TEN

in its dosage forms.

The results revealed that the oxidation of TEN is an

irreversible pH-dependent process in an adsorption-

controlled mechanism. The calibration curve was linear

in the concentration range of 8x10-8-1x10-6M with a

detection limit of 4,30x10-9M.

Figure 1. OSWSV of 4x10-6 M TEN at bare electrode

(blue line) and AgNps modified carbon electrode (red

line).

The OSWSV method was successfully applied for the

analysis of TEN from pharmaceutical dosage forms. No

electroactive interferences from the tablet excipients.

4. Conclusion

In the present work, the electrochemical behavior of

TEN was investigated by CV and OSWSV. In these

investigations, the effect of the pH of the buffer solution

and potential sweep rate were described. This study demonstrated that modification of GCE with AgNPs

was a new and sensitive application for the

electrochemical determination of TEN [1]. The method

was validated in accordance with ICH guidelines and

the obtained results were within acceptable criteria.

References

[1] N. Karadas, B. Bozal-Palabiyik, B. Uslu, S.A.

Ozkan, Functionalized carbon nanotubes—With

silver nanoparticles to fabricate a sensor for the

determination of zolmitriptan in its dosage forms

and biological samples, Sensors and Actuators B

186 (2013) 486–494

i p(µA)

Ep (mV)



Heteroarylboronic Acid Loaded Nanostructures:

Synthesis of 5-Pyrimidylboronic acid

G. Taskor1* and N.Saygili1

1 Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey


1. Introduction

The objective of this work was to formulate a

nanostructured possible biosensor with ability to choose

the diols. Boronic acids bind covalently with 1, 2- or 1,

3-diols to generate five or sixmembered cyclic

complexes. 5-Pyrimidylboronic acid has been

synthesised by lithium-halogen exchange reactions on

5-bromopyrimidine, followed by reaction with

triisopropylborate (Scheme 1). 5-Pyrimidylboronic acid

was formulated as nanostructured lipid carriers (NLCs)

and characterized for size, zeta potential and

morphology.


Procedure for the Preparation of 5-

Pyrimidylboronic acid [1]: To a solution of 5-

bromopyrimidine (5.50 g, 34 mmol) and

triisopropylborate (13.0 g, 69 mmol) in anhydrous THF

(70 mL) at -78oC was added n-BuLi (1.6 M in hexane,

22.0 mL, 35 mmol) dropwise. The reaction mixture was

stirred for 4 h at -78oC then quenched with H2O (10

mL) and allowed to warm to 20oC with stirring

overnight. The solvent was evaporated in vacuo and the

aqueous layer was taken to pH 10 with 5% NaOH and was then washed with diethyl ether. The aqueous layer

was then acidified to pH 4 with 48% aq HBr to

precipitate 5-pyrimidylboronic acid as a white solid

(1.90 g, 45%).

Scheme 1. Synthesis of 5-Pyrimidylboronic Acid

Procedure for Preparation of Nanostructures [2]: A

prewarmed oil phase (1 mL) consisting of fish oil and

125 mg of 5-pyrimidylboronic acid dissolved in ethanol

was gradually added to the prewarmed aqueous phase (4

mL) containing 120 mg of egg phosphatidylcholine

(Lipoid E80), 10 mg of polysorbate 80 (Tween 80), and

10 mg of stearylamine. The resultant mixture was

stirred for 2 min using a homogenizer at 6000 rpm and

ultrasonicated for 10 min using a probe sonicator at

22%amplitude and 50% duty cycle.

Figure 1. Tem image of nanostructure (scale bar = 200

nm)

3. Results

Characterization of 5-Pyrimidylboronic Acid: Mp

>320oC; 1H NMR (DMSO-d6) δ 9.36 (s, 1 H), 9.17 (s, 2

H), 8.81 (s, 2 H, OH); 13C NMR (DMSO-d6) δ 161.84,

159.31. Anal. calc. for C4H5BN2O2·0.5H2O: C, 36.15;

H, 4.55; N, 21.08. Found: C, 36.47; H, 4.50, N, 20.80%.

5-Pyrimidylboronic acid loaded nanoemulsions

formulated for the development of novel boronic acid-based biosensors.

4. Conclusion

This work support the way for further studies on

synthesis of pyrimidylboronic acids and regulation of

their nanostructures. Boronic acid-based nanoemulsion

sensors would be useful alternatives for the sensitive

and selective detection of biomolecules which have

diols.

References

[1] Saygili N., Batsanov A. S., Bryce M. R. Org.

Biomol. Chem., 2004, 2, 852-857. [2] Yadav S., Gattacceca F., Panicucci R., Amiji M. M.

Mol. Pharmaceutics, 2015, 12, 1523-1533.



Development of electrochemical biosensor based on graphene–chitosan

composite for sensitive detection of vinclozoline

G. Bolat1*, O. Surucu1 and S.Abaci1

1Hacettepe University, Department of Chemistry, 06532 Ankara, Turkey


Abstract

Pesticides are substances that are used to increase the

agricultural production by preventing the crop losses

from insects, herbicides or fungi. As a result of wide use

of pesticides in agrochemistry, there is a possibility to

run-off these toxic compounds into natural water bodies

and soil.

Vinclozoline, (VZ), 3-(3,5-dichlorophenyl)-5-methyl-5-

vinyl-1,3-oxazolidine-2,4-dione (Figure 1), is a

dicarboximide type of non-systemic fungicide that is

widely used for the control of several species of fungi in

vines (such as grapes), strawberries, vegetables and fruit

by inhibiting spore germination [1]. However, VZ, has

toxicity and functions as potential endocrine disruptor

that produces malformations in humans [2]. Also, the

low-solubility of fungicides in water may lead to serious environmental problems [3].

Considerable effort is being made to design sensitive

analytical methods for the detection of pesticides. The

mechanisms of reactions of dicarboximides and their

electrochemical behavior are still not known in detail.

The fabrication of electrochemical sensors based on

modified electrodes on the analytical determination of

pesticides has great amount of importance due to the excellent sensing properties [4]. Therefore, it is

important to discover appropriate electrode materials

to improve the performance for the pesticides sensing

[5]. Graphene films can be used as electrode materials

with electrocatalytic properties in their partially reduced

form. Graphene nanosheet (GN), in a honeycomb two-

dimensional (2D) sheet form, is a two-dimensional

carbon material which possesses novel properties, such

as large surface-to-volume ratio, well biocompatibility,

well mechanical properties and high electrical

conductivity. Graphene-based materials and nanocomposites show obvious superiorities on sensing

applications [6]. It has been reported that GR

nanosheets could be electrodeposited onto electrodes

through electrochemical reduction of graphene oxide

(GO) solution. Chitosan (CS) is a linear hydrophilic

nontoxic natural biopolymer that exhibits excellent

film-forming ability. Also, CS has been applied to

disperse nanomaterials. The GR–CS composite has been

shown as a suitable electrode material for pesticide

sensing, by facilitating the enrichment of pesticides on

the surface and improving the sensitivity [7].

To the best of our knowledge, there is no report on the

determination of VZ by using graphene-based

nanocomposite to VZ sensor. In this study, chitosan-

graphene matrix was used to fabricate the electrochemical sensor to determine the VZ.

Modification of the electrode surface and the

application for the detection of VZ was carried out

successfully. The high surface area of the composite

greatly increased the surface loading of VZ as sorbent

material.

Figure 1 Structure of vinclozolin.

1. References

[1] W.R. Kelce, E. Monosson, L.E. Gray, Recent

Progress in Hormone Research 50 (1995) 449–453. [2] S. Mc Gary, P.F.P. Henry, M.A. Ottinger,

Environmental Toxicology and Chemistry 20

(2001) 2487–2493.

[3] O. Belafdal, M. Bergon, J.P. Calmon, Pesticide

Science 17 (1986) 335–342.

[4] C.M.A. Brett, Pure Appl. Chem. 73 (2001) 1969–

1977.

[5] J.D. Fowler, J.M. Allen, V.C. Tung, Y. Yang, B.H.

Weiller, ACS Nano 3 (2009) 301–306.

[6] S. Stankovich, D.A. Dikin, G.H.B. Dommett,

K.M. Kohlhaas, E.J. Zimney, E.A. Stach, R.D. Piner, S.T. Nguyen, R.S. Ruoff, Nature 442

(2006) 282-286.

[7] T. Ramanathan, A.A. Abdala, S. Stankovich,D.A.

Dikin, M. Herrera-Alonso, R.D. Piner, Nat.

Nanotechnol. 3 (2008) 327-331.



Polydopamine Coated - SiNWs Target Surfaces for the Detection of Small

Molecules in Laser Desorption/Ionization Mass Spectrometry

G. Şanlı1*, G. Demirel2 and Ö. Çelikbıçak1

1 Department of Chemistry, Hacettepe University, Turkey,

2 Department of Chemistry, Gazi University, Turkey


1.Introduction

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a surface-based technique that has been widely employed for the analysis/detection of biomolecules. In this method, the choice of the suitable matrix and the sample/matrix mixing ratio, the methods of the sample preparation and the way of sample introduction upon MALDI plate can cause different consequences in mass spectral

results. Apart from that, the excess amount of matrix molecules makes difficult the analysis of the small analyte

molecules which can be observed under 1000 m/z in mass

spectra.[1] To overcome these problems, reusable solid surfaces were produced by polydopamine (PDOP) coating on silicone nanowires (SiNWs) and these surfaces were used as a laser desorption/ ionization (LDI) target in this study. In order to test the effects of PDOP thickness on laser desorption/ionization (LDI) process, the SiNWs were coated with PDOP layer with different thicknesses by manipulating

PDOP deposition time (3h, 6h, 24h). Fabricated surfaces were then characterized by various techniques such as XPS (X-ray photoelectron spectroscopy), SEM (Scanning electron microscopy) and ellipsometry. Finally, performances of fabricated surfaces as a LDI target were tested and evaluated using some model drug and peptide molecules, such as; acrivastine, angiotensin II and substance P in MALDI-TOF-MS studies.

2.Materials and method

The vertical aligned silicon nanowires were fabricated through well-established metal-assisted chemical etching technique. [2]

Within this context, p-type silicon wafers were first cleaned consecutive sonication in ethanol, acetone, and deionized water for 10 min. The wafers were then immersed into a H2O2

and H2SO4 mixture having a volume ratio of 1:3 at 70°C for 60 min in order to remove metal and organic residues from silicon wafer surfaces. Afterwards, the silicon wafers were transferred into HF solution for 1 min and subsequently immersed into a PTFE baker containing 4.6 M of HF and 0.02 M of AgNO3 (1:1, v/v) for 1 min. The samples were finally immersed into a mixture of HF and H2O2 (10:1, v/v) at 25°C for 10-120 min. Afterwards, the wafers having desired

nanowire lengths were removed and washed with deionized (DI) water and nitric acid to remove by-products. To deposit PDOP on SiNWs, the fabricated SiNW arrays were first immersed into a dopamine solution (pH=8.5, 2 mg/mL) for varying time intervals (3-24 h). The samples were then removed and cleaned with DI water and dried with N2 gas.


Polydopamine coated SiNWs was employed as a LDI target and some model compounds having different molecular structures such as; acrivastine (348,4 Da), angiotensin II (1046,1 Da) and substance P (1347,6 Da) were applied onto

these surfaces as sample. In these studies, different target surfaces, produced by different polydopamine coating periods (3h, 6h and 24h) were also utilized to investigate effects of polydopamine layer thickness on LDI-MS analysis (Figure 1). [M+H+] signal of the acrivastin drug molecule was successfully observed by using polydopamine coated surfaces prepared by 3h and 6h time periods. However, LDI-MS signal

of acrivastine was disappeared on 24h polydopamine coated SiNWs. In the case of angiotensin II and substance P studies, it was observed that signal intensities of both polypeptides were increasing by growing thickness of polydopamine layer on SiNWs. These results represent that thin polydopamine layer on SiNWs are affective for detecting small molecules, while thicker polydomamine coatings are successful for relatively higher molecular weight compounds such as small polypeptides.

Figure 1: Acrivastine, angiotensin II and substance P analysis

on different PDOP coated surfaces. (A) acrivastin on 6h-PDOP. (B) Angiotensin II on 6h-PDOP (C) Substance P on 6h-PDOP. (D) acrivastin on 24h-PDOP. (E) Angiotensin II on 24h-PDOP. (F) Substance P on 24h-PDOP.

References

[1] Çelikbıçak, Ö., Demirel, G., Pişkin, E., Salih, B., Small Molecule Analysis Using Laser Desorption/Ionization Mass Spectrometry on Nano-Coated Silicon with Self-Assembled Monolayers. Analytica Chimica Acta, 2012, 729, 54-61. [2] Li, X.; Bohn, P., Metal-Assisted Chemical Etching in HF/H2O2 Produces Porous Silicon. Applied Physics Letters 2000, 77 (16), 2572-2574.

10 408 806 1204 1602 2000 m/z

[M+H]+

*

***

**

K+

m/z10 208 406 604 802 1000

[2M+H

]+[M+H]+

F

F

F

F

FK+ F*

10 508 1006 1504 2002 2500 m/z

[M+H

]+

F*

**

***

***

*

K+

A

B

C

10 208 406 604 802 1000 m/z

10 408 806 1204 1602 2000 m/z

[M+H]+

*

K+

***

Na+

10 508 1006 1504 2002 2500 m/z

[M+H]+

*

K+

**Na+

D

E

F



Molecular Identification of Aspergillus and Penicilium Species with ITS-PCR

H. Halil Bıyık1, Bahadır Törün1, Yusuf Geroğlu1, Esin Poyrazoğlu Çoban1, Gamze Başbülbül1

1 Department of Biology University of Adnan Menderes,


1. Introduction

Difficulties and confusions about identificatrion of fungi

with tradiotinal methods have turned researches to

molecular methods [1]. ITS is one of the polymorphic

DNA sequences between fungal species, nowadays it is

seen as a good candidate in terms of determining fungi species correctly and with this application they can be

deperated to a large extend. Aspergillus and Penicillium

have both positive and negative effects on human

aktivities, and widely distributed species. Some of the

species of this genus can be pathogenic while some of

them have industriel importance [2]. In this study

Aspergillus and Penicillium species in our stocks were

identified with molecular methods and long term

storage is provided.


In study, Aspergillus and Penicilium species which previously isolated and identified with morphological

methods and recorded at ADÜ Biology Department

stocks were used. DNA isolations of the samples were

made according to Tran-Dinh et al., (1999) [3]. DNA

concentration and purity control of the samples were

made with Nanodrop Spectrophotometer (Thermo).

Universal ITS 1 and ITS 4 primers were used for

molecular identification. PCR products were sent to

Macrogen (Holland) company for sequencing and

matched using BLASTn software.


One hundered twenty samples were matched with

GenBank using BLASTn software (GenBank;

http://ncbi.nlm.nih.gov) and 20 of the samples were

Aspergillus fumigatus, 12 of them were A.awamori, 9

of them A.niger, 6 of them A.tubingensis, 9 of them

A.terreus, 4 of them A.japonicus, 5 of them A.oryzae,

2 of them A.tamarii, 5 of them Penicilium commune, 6

of them P.chrysegeum, 2 of them Fusarium sp., 3 of

them Mucor circinelloides, 2 of them Lichtheimia

corymbifera, 1 of each Aspergillus versicolor,

A.brassiliensis, A.flavus, Penicillium griseofulyum, P. restrictum, Fusarium proliferatum, F. chlamydosporum,

Trichoderma saturnisporum, T. atroviride, T.

harzinarum, Alternaria promicola, Purpurecilium

lilacinum, Cladosporium cladosporioides, Eurotium

cristatum and Cytospora sp. were found (Table 1).

Mycelia and spores of Aspergillus and Penicillium were

lyophilizied and cathologed.

Classical parameters which used for identification of

microfungi includes; microscopic morphology,

physiological tests, cultural and clinical properties. But

uncertanity of phenotipic chracters makes harder to

identify species with morphological methods. Therefore

molecular approaches became an alternative method for identification of fungi. Lyophilisation and liquid drying

is difficult techniques for preserving fungi mycels and

spores. These techniques are especially used for

stocking and preserving mycels and spores over 20

years.

Table 1 Name of species and number of samples

identified

4. Acknowledgements

This research was supported by supported Adnan Menderes

University Research Fund. Project Number: ADU-BAP-FEF–10003.

References

[5] Edman JC, Kovacs JA, Masur H, Santi DV, Elwood HJ, Sogin

ML (1986) Ribosomal RNA sequence shows Pneumocystis

carinii to be a member of the fungi. Nature 334:519–522.

[6] Logrieco A, Peterson SW, Wicklow DT (1990) Ribosomal

RNA comparisons among taxa of the terverticillate penicillia.

In: Samson RA, Pitt JI (eds) Modern concepts in Penicillium

and Aspergillus classification. Plenum, New York, pp 343–356.

[7] Tran-Dinh, N., Pitt J.I., Carter D.A. 1999. Molecular genotype

analysis of natural toxigenic and nontoxigenic isolate of

Aspergillus flavus and A. parasiticus. Mycological Research,

103, 1485 –1490.


http://ncbi.nlm.nih.gov/

http://tureng.com/tr/turkce-ingilizce/lyophilisation


Zinc-Nickel nanostructures coated f-MWCNT nanocomposite electrode for

nonenzymatic glucose biosensing

Fatih Şen1, Yağmur Koşkun1, Hakan Sert1*, Gaye Başkaya1 and Aysun Savk1

1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupınar University, Kütahya,

Turkey


Abstract

Mesoporous ZnO-NiO architectures were prepared by

thermal annealing of zinc-nickel hydroxycarbonate

composites [1]. The resulting architectures are shown to

be assembled by many mesoporous nanosheets, and this

results in a large surface area and a strong synergy

between the ZnO and NiO nanoparticles [2]. The obtained material was used as an electrode that responds

to glucose over a wide concentration range (from 0.5

μM to 6.4 mM), with a detection limit as low as 0.5 μM,

fast response time (<3s), and good sensitivity (120.5

μA·mM−1·cm−2) [3].

Figure 1. Cyclic voltammograms of the

GC/MWNT/NiO in the presence of 0.01 M

glucose at varying scan rates: (a) 10, (b) 20,

(c) 40, (d) 60, (e) 80, (f) 100, (g) 150 and

(h)200 mV s−1, respectively

References

[1] Liu, Q., Lu, X.B., Li, J., Yao, X., Li, J.H., (2007),

Biosens. Bioelectron. 22; 3203–3209. [2] Zeng, Q., Cheng, J.S., Liu, X.F., Bai, H.T., Jiang,

J.H., (2011), Biosens. Bioelectron. 26; 3456–3463.

[3] Ding, Y., Wang, Y., Su, L., Bellagamba, M., Zhang,

H., Lei, Y., (2010), Biosens. Bioelectron. 26; 542–548.




Surface Plasmon Resonance Imaging (SPRi) on a Smartphone for Point-of-care

Applications Hasan Guner1*, Erol Ozgur1, Guzin Kokturk2, Mehmet Celik3, Elif Esen2, Ahmet E. Topal1, Sencer Ayas4,

Yildiz Uludag2, Caglar Elbuken1 and Aykutlu Dana1

1UNAM, Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey 2 UEKAE-BILGEM, TUBITAK, Gebze/Kocaeli, 41470, Turkey

3 Department of Computer Engineering, Middle East Technical University, Ankara, 06800, Turkey 4 Department of Radiology, Stanford School of Medicine, Palo Alto, CA 94304, USA


1. Introduction

We demonstrate an on-chip plasmonic imaging platform integrated with a smartphone to be used in the field with high-throughput biodetection. Inexpensive and disposable SPR substrates are produced by metal coating of commercial Blu-ray discs [1,2]. Real-time bulk refractive index change measurements yield noise equivalent refractive index changes as low as 4.12 x 10-5 RIU which is comparable with the

detection performance of commercial instruments. We have shown capture of mouse IgG antibodies by immobilized layer of rabbit anti-mouse (RAM) IgG antibody with nanomolar level limit of detection. Our approach in miniaturization of SPR biosensing in a cost-effective manner could enable realization of portable SPR measurement systems and kits for point-of-care applications.


We designed a compact optical system, using a 3D-printed apparatus that hosts the LED source, collimator, bandpass filter, linear polarizer, beamsplitter plate and an external

imaging lens which can be easily attached to the smartphone (Figure 1). We employed a silver-gold bilayer structure coated on the periodic corrugations of Blu-ray discs in order to perform plasmon resonance imaging at the central region of

r~500 nm) under normal incidence illumination in aqueous environment (Figure 2). This allowed the optimal use of the CMOS sensor of the smartphone while maintaining high sensitivity, chemical stability and biological

affinity. A microfluidic channel is placed on the bi-metallic layer for controlled plumbing of the liquids. The use of Blu-ray discs and standard metal deposition techniques together with the low-cost microfluidic channel resulted in significant cost-reduction which can allow the system to be used for applications requiring disposable SPR biosensors.

Figure 1. Surface plasmon resonance imaging platform integrated with a smartphone

Figure 2. Grating coupled SPRi sensor chip

3. Results

SPR chip immobilized with RAM IgG is taken out the spectral interrogation setup (Figure 3a) and plugged into the smartphone attachment. Mouse IgG solutions at concentrations ranging from 1.33 nM to 830 nM were injected successively. Intensity changes of individual pixels at three distinct locations on the sensor surface is shown in Figure 3b. Dose-response curve reveals that nanomolar level detection of

antibody analyte is achievable within a dynamic range from a few nanomolars to micromolar concentration.

Figure 3 Nanomolar level detection of capture of mouse IgG

by immobilized layer of RAM IgG. (a) Spectral sensorgram showing the immobilization steps of RAM IgG. (b) Dose-response curve for the capture of mouse IgG.

References

[1] B. Turker, H. Guner et al. Lab Chip 11, 282 (2011) [2] B. Kaplan, H. Guner et al. Plasmonics 4, 237 (2009)



The Synthesis and Characterization of PEI Modified Fe3O4/Au Nanoparticles

for Rapid Enumeration of E. coli

Hasan İlhan1*, Üzeyir Doğan2, Hakan Çiftçi3, Uğur Tamer2 and Necdet Sağlam1

1Department of Nanotechnology and Nanomedicine, Hacettepe University, Ankara, 06800, Turkey 2Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, Ankara, 06330, Turkey

3Department of Chemistry and Chemical Processing Technologies, Kirikkale Vocational High School, Kirikkale

University, Kirikkale, 71450, Turkey


1. Abstract:

Magnetic nanoparticles have been utilized as a powerful tool in various bioassays and used as solid support

owing to its advantages such as biocompatibility,

stability and immunomagnetic seperation. Modification

of these nanoparticles enable to straightforward

conjugation with bacteria or biomolecules of interest

[1,2]. Numerous magnetic nanoparticles have been

developed as magnetic carriers or separation and

purification process [3]. Polyethyleneimine (PEI) is a

water soluble cationic polymer consisting of amino and

imino groups which are expected to adsorb onto the

surface of gold coated magnetic nanoparticles [4]. Fe3O4/Au-PEI nanoparticles were synthesized in

aqueous solution and characterized by transmission

electron microscopy (TEM), UV-Vis

spectrophotometer, zeta potential and particle size

distribution.

2. Materials and Methods:

In this study, we report the preparation of magnetic

nanoparticle and modification of this nanoparticle specific to E.coli. This modified magnetic nanoparticle

provides immunomagnetic separation and specific

detection of the target bacteria. Enzyme substrate is

covalently linked between magnetic particle and target

bacteria to cleave bond easily using an enzyme. Then,

magnetic nanoparticle is cleaved from E. coli in order

not to prevent bacteria movement on the test strip. β-

casein is a good substrate for this application and yeast

enzyme is used for bond cleavage. The amide bonds of

β-casein on the magnetic particle-casein-biotin are

cleaved by the enzyme to release some or all of the biotin moieties from magnetic particle [5]. The

magnetic particles are removed by a magnet, and the

target bacteria in the solution can be detected efficiently

on the test strips. The target bacterium is also labeled

with horseradish peroxidase enzyme to enable

colorimetric detection on the test strip. Detection pad is

spotted with E. coli antibody, 3,3’,5,5’-

tetramethylbenzidine (TMB) and hydrogen peroxide

solutions to catch labelled bacteria and observe colored

product, respectively [6]. Colorimetric measurements

are taken on this spot with a portable CCD camera to

construct a calibration curve which enables quantitative analysis.

3. Conclusion

We believe that this new immunomagnetic sensing platform can be used in many application areas

including food quality, water contamination, clinical

diagnosis and environmental monitoring due to its

attractive advantages such as simple, low-cost, portable

and disposable features.

4. References:

[1] U. Tamer, A. Onay, H. Ciftci, and J. M. Greneche, J.Nanopart Res 16, 2624, (2014)

[2] U. Tamer, D. Cetin, Z. Suludere, I. H. Boyaci, and

Y. Elerman, Int. J. Mol. Sci.14, 6223, (2013)

[3] C. Wang, J. Xu, J. Wang, Z. Rong, P. Li, R. Xiao, S. Wang, J. Mater. Chem. C, 3, 8684, (2015)

[4] H. Ciftci, E. Alver, F. Celik, A. U. Metin, U. Tamer,

Microchim acta 183, 1479, (2016)

[5] W. Ren, I-H. Cho, Z. Zhou, and J. Irudayaraj, Chemcom 52, 4930, (2016)

[6] D. Kwon, S. Lee, M. M. Ahn and S. Jeon, Analytica

Chimica Acta, 883, 61, (2015)




Detection of Listeria Monocytogenes Using Anisotropic Magnetic Nanoparticle

Based Surface Enhanced Raman Spectroscopy

Hande Yeğenoğlu1, Hilal Torul2*, Adem Zengin3, Belma Aslım1, Demet Çetin4, Zekiye Suludere1, İsmail Hakkı

Boyacı5,6, and Uğur Tamer2

1Department of Biology, Faculty of Art and Science, Gazi University 06500, Ankara, Turkey 2Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, Etiler, Ankara 06330, Turkey

3Department of Chemical Engineering, Yüzüncü Yıl University, Van 65080, Turkey 4Science Teaching Programme, Gazi Faculty of Education, Gazi University, Besevler, Ankara 06500, Turkey

5Department of Food Engineering, Hacettepe University, Beytepe, Ankara 06800, Turkey 6Food Research Center, Hacettepe University, 06800 Beytepe, Ankara, Turkey


1. Introduction

Diseases caused by bacterial pathogens are intense

concerns due to occurrence of high death rate in the world [1]. For this reason, detection of bacterial

pathogens in food products has an importance. Although there are several detection methods developed

for this purpose, these conventional methods usually

include microbiological culturing and plating, which are

time-consuming due to consist of several enrichment

steps. In addition to conventional methods, some

different techniques including flow cytometry [2],

enzyme-linked immunosorbent assay (ELISA) [3], and

polymerase chain reaction (PCR) [4] have been

developed. Nevertheless, these techniques have some limitations such as sensitivity, specificity, speed, and

cost efficiency. As a result of these limitations,

development of a new method is significantly necessary

to detect low concentrations of pathogens in different

media [5]. In this work, a highly selective and sensitive

SERS system was developed for immunomagnetic

separation and detection of Listeria monocytogenes in

milk sample.

2. Experimental

Anisotropic magnetic gold nanoparticles with SERS

active properties were synthesized and used in

immunoassay systems. In order to collect L. Monocytogenes bacteria from milk sample, bacteria

were interacted with novel antibody conjugated

magnetic Fe-Au nanoparticles. Then the collected

bacteria were interacted with DTNB labeled gold

nanoparticles to measure amount of Listeria

monocytogenes in milk sample.

3. Result

The calibration curve was obtained with the changes of

the peak intensities of NO2 stretching band versus

different L. monocytogenes bacteria concentrations.

Figure 1. The decrease of the peak intensity at 1333 cm-

1 illustrated symmetric NO2 stretching bands of DTNB

at increasing L. monocytogenes concentrations

obtained with magnetic gold nanoparticles; a) no

Listeria monocytogenes , b) 2,2 x 101 cfu/mL, c) 2,2 x

102 cfu/mL, d) 2,2 x 103 cfu/mL, e) 2,2 x 104 cfu/mL, f)

2,2 x 105 cfu/mL, g) 2,2 x 106 cfu/mL

The SERS response was found to be linear between the

concentration of bacteria in range 2,2x101-106 cfu/mL. (R2: 0.991).

References

[1] Yang L. and Bashir R., Biotechnology Advances,

2008, 26, 135–150.

[2] Kempf V.A.J., Mandle T., Schumacher U., Schafer

A. and Autenrieth I. B., Int. J. Med. Microbiol., 2005,

295, 47−55.

[3] Dylla B.L., Vetter E.A., Hughes J.G., and Cockerill

F.R., J. Clin. Microbiol., 1995, 33, 222−224.

[4] Belgrader P., Benett W., Hadley D., Richards J.,

Stratton P., Mariella R. and Milanovich F., Science, 1999, 284, 449−450.

[5] Zhou H., Yang D., Ivleva N.P., Mircescu N.E. and

Niessner R., Anal. Chem., 2014, 86, 1525−1533.



Synthesis of DNA Aptamer Conjugated Magnetic Graphene Oxide and Its Use

As A Photo-thermal Agent for Killing Methicillin-Resistant Staphylococcus

Aureus

Ismail Ocsoy1*

and Muserref Arslan Ocsoy2

1Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey

2Department of Physics, Faculty of Science, Erciyes University, 38039 Kayseri, Turkey;


The detection and destruction of bacteria is not only important for human and animal health but also for

industry and crop production security. Staphylococcus

aureus (SA) which is the one of the most dangerous

disease-causing bacteria exhibits the resistance to

various antibiotics. The methicillin resistant

staphylococcus aureus (MRSA) is one of the most

dangerous pathogenic (disease-causing) bacteria is

usually called “superbug”8-10. It The has been high

demand to develope alternative and effective

approaches rather than using antibiotics in order to

efficiently detect or destruct the MRSA.

In this study, a multifunctional nano platform was

developed for detection and photothermally destruction

of MRSA bacteria. Magnetic GO functionalized with

MRSA aptamers was produced for this purpose. First of

all, the iron oxide (Fe3O4) nanoparticles (NPs) were

grown on the surface of the GO and magnetic GO

(mGO) was functionalized the aptamers modified with

amin (-NH2) group on one end that were specifically

synthesized for MRSA. The MRSA bacteria were

rapidly, sensitively and accurately captured with

aptamer functionalized mGO (Apt@mGO) and it was photothermally destroyed under the near infrared laser

(NIR, 808 nm). While aptamer specifically binds to

MRSA, MRSA were magnetically separated with a

magnet without centrifugation due to Fe3O4 NPs on the

surface of the GO. While GO is used as a platform for

aptamer and Fe3O4 NPs, it is utilized a photothermal

agent converting laser light to heat when exposed to 808

nm NIR laser. Also, it is considered that GO tightly

wraps the MRSA bacteria due its sheet shape and

carrying several functional groups on the surface.

Figure 1. Illustration of the binding of Apt@mGO to MRSA and cell destruction throught PTT

Figure 2. Illustration of the suspension and aggregation

Apt@mGO-MRSA bacteria.

References

[1] Lancet. Infect. Dis. 2010, 10, 597–602.

[2] Arch Intern Med.1998, 158, 895–899.

[3] Proc. Natl. Acad. Sci. U.S.A. 2006, 103, 11838–

11843.

[4] ACS Nano, 2013, 7, 8972-8980.

[5] RSC Adv. 2016, 6, 30285-30292.

[6] ACS Nano, 2013, 7 (2), pp 1281–1290



The Investigation of DNA Binding Profiles of Gold Nanoparticle Bound Lignan

Species Called Lariciresinol Using Spectrophotometry and Spectrofluorimetry

İsmail Murat Palabıyık1*, Nuri Özmen

1, Mehmet Gökhan Çağlayan

1 and Feyyaz Onur

1

1Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara,Turkey


1. Introduction

Owing to both the life style and environmental

problems; nowadays frequency of prevalence of cancer

diseases highly increased so far as the past years.

Lignans, also called phytoestrogens, are one of the main

groups of herbal components. In recent years, in vitro,

animal and some epidemiological studies have reported the possibility of lignans to be used in treatment of

prostate, breast and colon cancers via antiestrogenic,

antiangiogenic, antioxidant and proapoptotic

mechanism [1,2].

2. Scope

Within the scope of studies of this study, connection of

lignan species namely lariciresinol to gold nanoparticles

modified by β-cyclodextrine were achieved and

interactions of pure and connected form of lariciresinol

with single and double strand DNA were established

using with spectrophotometric and spectrofluorimetric methods.

3. Results and Conclusion

In this study, interaction between pure and bounded

form of lariciresinol and double strand DNA were

investigated in different pH, ionic strength and

temperature. In spectrums obtained from

spectrophotometry, there is an increase in absorbances,

batochromic shift in bounded form (Figure 1) and

hypsochromic shift in pure form. Beside this, an

isosbestic point was observed and binding constant was

changed in different ionic strength. In spectrofluorimetric measurements, a quenching (Figure

2) was observed with increasing in DNA concentrations.

Also, Ksv values are decreased with increasing in

temperature (except 313 K). These findings are shown

that there is a binding between DNA and lariciresinol

and this binding is occurred both intercalation and

groove binding way [3].

Figure 1. Observed spectrums of LARI - β-CD-AuNP

with increasing concentrations in dsDNA 0.1 M

Na2HPO4 (pH: 7.40)

Figure 2. Observed florescence spectrums of

LARI - β-CD-AuNP with increasing in dsDNA

concentrations in 0.1 M Na2HPO4 (pH: 7.40)

Table 1. Ksv values for interactions between LARI - β-CD-AuNP and dsDNA in different experimental medium

Experimental conditions Ksv values

pH 4.40 0.01 M

NaH2PO4

1350.50

pH 7.40 0.01 M

Na2HPO4

1101.40

pH 8.40 0.01 M

Na2HPO4

831.32

0.05 M NaCl 1130.60

0.10 M NaCl 1068.20

0.20 M NaCl 1078.60

298 K 969.06

303 K 1278.60

308 K 1522.50

313 K 1282.70

Acknowledgements: This study was supported by The


Turkey, Grant SBAG-112S591

References

[1] Chen, J., Thompson, L.U. Breast Cancer Research and

Treatment, 80, 163–70, 2003.

[2] Chen, L.H., Fang, J., Sun, Z., Li, H., Wu, Y., Demark-

Wahnefried, W., Lin, X. Journal of Nutrition, 139, 653-9, 2009.

[3] Sirajuddin, M., Ali, S., Badshah, A. Journal of Photochemistry and Photobiology B Biology, 124, 1 – 19, 2015.

600 650 700 750 8000

100

200

300

400

Wavelength (nm)

Inte

nsity (

a.u

.)



A Novel Hydrogel System for the Wound Healing in the Diabetic Patients

K. A. Usal1,2* and T. Dursun3,4

1 Department of Cognitive Science, Middle East Technical University

2 Department of Research and Development, İleri Biyotek Biomedical R&D Company, 3 Department of Biotechnology, Middle East Technical University

4 Department of Biological Sciences, Middle East Technical University


1. Introduction

Wound healing is a specific biological process related to

the general phenomenon of growth and tissue

regeneration [1]. It includes a series of interdependent and overlapping stages in which a variety of cellular and

matrix components act together to reestablish the

integrity of damaged tissue and replacement of lost

tissue [2]. Diabetic patients have severe problems in the wound healing process due to the damaged blood flow

to the required areas [3]. Therefore, any minor scar can

turn into ulcers in the extremities, especially feet. If

these scars are not treated, these problematic wounds

would cause amputation. Nowadays, general wound

cleaning procedures are applied to treat the patients,

however, these treatments are not enough to provide a

complete healing.

Hydrogels contain significant amounts of water (70-

90%) and possess most of the desirable characteristics

of an ‘ideal dressing’ [4]. Experimental studies in animals have demonstrated that the topical application

of epidermal growth factor accelerates the rate of epidermal regeneration of partial-thickness wounds and

second-degree burns [5]. In this study, a hydrogel loaded with epidermal growth factor (EGF) will be

produced to improve the healing process in the diabetic

patients. This hydrogel system can also be used in any

type of wound to provide a faster and improved healing

process.


Hydrogel was composed of methacrylated gelatin.

Therefore, methacrylation of gelatin was done. gelatin

was dissolved in water and methacrylic anhydride (3%,

v/v) was added dropwise, and the reaction run for 2 h at

50˚C. The solution was dialyzed against distilled water. Methacrylated gelatin (GELMA) obtained was dried

with lyophilisation and stored at 4˚C. Crosslinking of GELMA hydrogel was achieved with UV exposure (at

365 nm) (Figure 1).


Characterization studies showed that these GELMA

hydrogels have appropriate pore size (100 (µm) and porosity (75%) for the cell attachment and the

proliferation studies. Water content of the GELMA

hydrogels was found as 95% (w/w). Therefore, it can be

classified as high water content hydrogel and its

biocompatibility is expected to be high.

After the characterization studies, in vitro performances

of the EGF-loaded GELMA hydrogels will be

performed. At the end, a growth factor loaded hydrogel

system will be produced for the use of diabetic patient’s wounds.

Figure 1 Synthesis of methacrylated gelatin. Gelatin

macromers containing primary amine groups were reacted

with methacrylic anhydride (MA) to add methacrylate pendant

groups (A). To create a hydrogel network, the methacrylated

gelatin was crosslinked using UV irradiation in the presence

of a photoinitiator (B) Taken from Khademhosseini et al.,

2010 [6].

References

[1] Boateng, J. S., Matthews, K. H., Stevens, H. N., &

Eccleston, G. M. (2008). Wound healing dressings and drug delivery systems: a review. Journal of pharmaceutical sciences, 97(8), 2892-2923.

[2] Rothe M, Falanga V. 1989. Growth factors, their biology and promise in dermatologic disease and tissue repair. Arch Dermatol125: 1390–1398.

[3] Moura, L. I., Dias, A. M., Carvalho, E., & de Sousa, H. C. (2013). Recent advances on the development of wound

dressings for diabetic foot ulcer treatment-A review. Acta biomaterialia, 9(7), 7093-7114.

[4] Morgan DA. 1999. Wound management products in the drug tariff. Pharm J 263:820–825.

[5] Brown, G. L., Nanney, L. B., Griffen, J., Cramer, A. B.,

Yancey, J. M., Curtsinger III, L. J., ... & Lynch, J. B. (1989). Enhancement of wound healing by topical treatment with epidermal growth factor. New England Journal of Medicine, 321(2), 76-79.

[6] Nichol, J. W., Koshy, S. T., Bae, H., Hwang, C. M., Yamanlar, S., & Khademhosseini, A. (2010). Cell-laden microengineered gelatin methacrylate hydrogels. Biomaterials, 31(21), 5536-5544.



Adsorptive stripping determination of Ezetimibe in pharmaceutical dosage

forms and biological fluids

L. Karadurmus1,2*, S. Kurbanoglu2, B. Uslu2 and S.A. Ozkan2

1 Adıyaman University, Faculty of Pharmacy, Department of Analytical Chemistry, Adıyaman Turkey

2 Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, Ankara, Turkey


1. Introduction

Electroanalytical methods emerge with the interplay

between electricity and chemistry; in other words they

were used to measure electrical quantities, such as

current, potential, or charge and their relationship with

the chemical parameters. These methods are widely

used in fields like environmental monitoring, industrial

quality control or biomedical analysis [1]. Another field

in which electrochemical methods are extensively used

is drug analysis and these methods have proved to be

highly sensitive due to the straight forwardness, low cost and relatively short analysis time [2].

Glassy carbon electrode (GCE) is the most common

carbon-based electrode because of its excellent

mechanical and electrical properties, wide potential

range, chemically inert nature and impermeability to

gases. They are easily mounted, polishable and

compatible with all common solvents. They allow many

applications in many different areas, since their

performances are relatively reproducible. Ezetimibe

((3R,4S)-1-(4-fluorophenyl)-3-[(3S)-3- (4-fluorophenyl)

-3-hydroxyl propyl)] -4-(4-hydroxy phenyl)-2-azetidinone) is a drug that inhibits cholesterol

absorption from the small intestine, which was

approved by the US Food and Drug Administration for

the treatment of primary hypercholesterolemia [3,4].

2. Experimental

Voltammetric measurements were recorded using BAS

100 W (Bioanalytical System, USA), electrochemical

analyzer with a standard three-electrode configuration.

The three electrode system consisted of a GCE (BAS: Ф

= 3 mm, diameter) as working electrode, a platinum

wire counter electrode, and an Ag/AgCl saturated KCl reference electrode. GCE was polished manually with

aqueous slurry of alumina powder (Ф = 0.01 μm) on a

damp smooth polishing cloth (BAS velvet polishing

pad) just before each measurement. All measurements

were achieved at room temperature.

In this study, the electrochemical behavior of Ezetimibe

was investigated using adsorptive stripping differential

pulse voltammetric method.

3. Results

The electrochemical behavior of Ezetimibe was

investigated with in a wide pH range (pH 0.3-7.0) using

adsorptive stripping differential pulse voltammetric technique at glassy carbon electrode. With adsorptive

stripping differential pulse voltammetric technique,

maximum current was observed in the pH 0.3 sulfuric

acid medium. As a result of scan rate studies, in the pH

0.3 sulfuric acid medium, the electrochemical behavior

of ezetimibe was found adsorption-controlled. From the

relation between Ep and logarithm of scan rate,

Ep=Eo+(2.303.RT/ά.n.F)logv n was calculated as 2.38.

Since ά is accepted as 0.5 for irreversible systems. The

peak potential was shifted to more negative values with

increasing pH. From the slope of the equation Log (Ip) =

0.78 log v – 1.19 (r=0.998) it can be resulted that the

reaction is adsorption controlled since the slope is close to 1. The Ep–pH equation of ezetimibe; Ep=998.49-

50.99 pH indicates that equal numbers of protons and

electrons are involved in the electrode reaction at GCE.

Under optimized deposition time and potential

conditions using adsorptive stripping differential pulse

voltammetric technique Ezetimibe was determined

concentration from 1x10-6 M to 2.5x10-5 M with a limit

of detection as 0.32 nM and limit of quantification as 1

nM. In optimized conditions, Ezetimibe determination

was achieved in human urine, and human serum. For the

validation of the proposed methods, precision and accuracy were examined by assaying five replicate

samples as individual days (within day) and

intermediate precision (between days). Relative

standard deviations (RSD %) and bias % were

calculated to check the precision of the method. After

statistical evaluation the results indicate that method is

analytically acceptable from the view point of precision

[5].

References

[1] J. Wang, “Analytical Electrochemistry”, Wiley-Vch,

New Jersey, 2006. [2] S.A. Ozkan, “Electroanalytical methods in

pharmaceutical analysis and their validation”, HNB

Pub., New York, 2011.

[3] L. L. Brunton, “Goodman and Gilman’s: The

pharmacological basis of therapeutics”, McGraw Hill

Press, New York, 2010.

[4] S. C. Sweetman, “Martindale: The Extra

Pharmacopoeia”, 35th edition. Pharmaceutical Press,

London, 2007.

[5] J. Ermer and J. H. Miller, “Method Validation in

Pharmaceutical Analysis”, Wiley-VCH, Weinheim,

2005.



A Paper-based Platform for Optical Sensing of Dopamine by Graphene

Quantum Dots

M. Esad Sağlam1*, Aylin Arıcı1, Ilker Akin2, Erhan Zor3 and Haluk Bingol4

1 Institute of Science, Necmettin Erbakan University, Konya, Turkey

2 Department of Chemistry, Selçuk University, Konya, Turkey 3 Department of Science Education, Necmettin Erbakan University, Konya, Turkey

4 Department of Chemistry Education, Necmettin Erbakan University, Konya, Turkey


Abstract

Dopamine (DA) given in Figure 1 is one of the most

influential neurotransmitter in mammalian central

nervous system. Thus, its detection is very crucial for

the diagnoses, monitoring and treatments of several

neurological disorders such as Schizophrenia and

Parkinson’s disease. Different analytical methods have

been reported for DA determination, such as

chromatography combined with mass spectrometry,

optical and electrochemical techniques [1]. Although the methods can reach very low detection limits, the

procedures require not only sample pretreatment,

lengthy analysis times and high costs.

Figure 1 Structure of DA

In the recent years, many researchers have focused on

optical and electrochemical paper-based sensors which

are a new alternative technology for fabricating simple,

low-cost, portable and disposable analytical devices [2]. In fabricating paper-based sensors, the choice of

materials that meet the criteria of simplicity and

efficient production process need to be considered.

There are different optical materials involving simple

organic molecules, nanoparticle and quantum dots that

could be used to tune the optical and sensing properties

of the paper-based sensor. Graphene quantum dots

(GQDs), as a class of fluorescent probes, have attracted

considerable attention in recent years. Compared with

metal based quantum dots, GQDs have high photo-

stability, low toxicity, simple synthesis ways as well as tunable fluorescence emission properties, which gained

them increased attention in a variety of applications [3].

Herein, we report a novel, low cost, disposable, rapid

and straightforward paper-based platform embedded

photoluminescent GQDs for optical sensing of DA in

aqueous media. GQDs was prepared by top-down

synthesis based on acidic oxidation cutting of graphene

oxide (GO) following the literature [4]: GO firstly

synthesized using the improved Hummers method was

re-oxidized in HNO3 for 20 h at 90˚C. The mixture was

further dialyzed in a dialysis bag (MWCO: 2 kDa). The

GQDs were characterized by FT-IR, Raman, XPS and TEM. The water-soluble fluorescent GQDs is

transferred onto a commercial paper for “yes/no” type

optical sensing of DA by spotting and then dried to

remove the solvent. The orange emitting GQDs exhibit

excitation independent PL behavior. On excitation of the

absorption band of 470 nm, the PL spectrum of GQDs

exhibits a highest peak at 580 nm with a Stokes shift of

110 nm as can be seen in Figure 2. The fluorescence

intensity of the GQDs in aqueous media turned out to

decrease sensitively when interacted with DA molecules

(the inset of Fig. 3). It displayed the fluorescence

change as a function of the concentration of DA from

6.0 µM to 120.0 µM in harmony with the literature [5].

The charge transfer between GQDs and DA molecules linked by hydrogen bonding and electrostatic interaction

was suggested to be responsible for the fluorescence

quenching of the GQDs.

Figure 2 The fluorescence excitation and emission spectra of

the GQDs dispersed in water

Figure 3 The fluorescence sensing of DA by commercial paper embedded GQDs.

Figure 3 demonstrates the fluorogenic detection of DA

using GQDs on the commercial paper. Once the paper-

based sensor was fabricated, the DA solution was

dropped onto the loading zone. The PL quenching showed the presence of DA in aqueous media.

Acknowledgement: The authors are grateful to the Scientific Research Projects of Necmettin Erbakan University (161310004) for financial support.

References [1] Polo, E. and Kruss S. Anal Bioanal Chem. 408 (2016), 2727-41.

[2] Liana D.D. et al., Sensors, 24 (2012), 11505-26.

[3] Zheng X.T. et al., Small, 11 (2015), 1620–1636. [4] Fan L. et al., Talanta, 101 (2012), 192–197.

[5] Zhao et al., Sensors & Actuators, B: Chemical, 223 (2016), 246-251.



Electropolymerized Films of 1,3-Bis(2-pyridylimino)isoindolato-palladium

Complex: Biosensor Applications

Metin Ak1, Tuğba Soğancı1, Tuğçe Yazıcı Tekbaşoğlu2, Atıf Koca3 and M. Kasım Şener2*

1 Department of Chemistry, Pamukkale University, 20017 Denizli, Turkey

2 Department of Chemistry, Yıldız Technical University, 34210 İstanbul, Turkey 3 Department of Chemical Engineering, Marmara University, 34722 İstanbul, Turkey


1. Introduction

The chemistry of isoindolines has been the key for the

development of phthalocyanines as well as related

macrocycles and chelating ligands [1]. Among the

isoindoline-based chelating ligands, bis(2-

pyridylimino)isoindolines (BPI) have been the focus of

interest because they are readily synthesized and easily

modified. [2]. Most of the published papers about bis(2-

pyridylimino)isoindolines and their metal complexes

focused on structural characterization and main application areas of these compounds are homogeneous

catalysis and biomimetics [3]. Here, we present first

time a new bis(2-pyridylimino)isoindolato-palladium

complex bearing electropolymerizable EDOT (3,4-

(ethylenedioxy)thiophene) substituent and show it may

be used for glucose sensing as heterogeneous catalytic

system.

2. Experimental

Monomer palladium complex EDOT-PdBPI was

synthesized from EDOT-BPI [4] (Figure 1).

Polymerization of synthesized monomer and

copolymerization with HKCN [5] were carried out by an electrochemical method. In addition to all of these, a

simply fabricated amperometric glucose sensor based on

glucose oxidase (GOx), P(EDOT-PdBPI-co-HKCN)

modified graphite rod electrode was improved.

O O

S

O

NN N

N NPd

Cl

NS S

NHO

NH2

EDOT-PdBPI HKCN

O O

S

O

HNN N

N N

EDOT-BPI

Figure 1. Structural formulas of monomers


In our matrix, amino groups which are arising from the

HKCN were used for the enzyme immobilization. On

the other hand, the presence of EDOT-PdBPI serves an

extra electron by reason of the oxidation of H2O2 to O2. Amperometric detection was carried out following

oxygen consumption at -0.7 V vs. the Ag reference

electrode in phosphate buffer (50 mM, pH 6.0). The

proposed sensor showed a linear amperometric response

for glucose within a concentration range of 0.25 mM to

2.5 mM (LOD: 0.176 mM). Amperometric signals at 1

mM of glucose were 17.9 μA under anaerobic

conditions. Amperometric signals of the P(EDOT-

PdBPI-co-HKCN)/GOx electrode decreased by 13%

within eight week. The P(EDOT-PdBPI-co-

HKCN)/GOx electrode showed excellent selectivity in

the presence of ethanol and phenol. This result shows

that, modification of the proposed sensor by glucose oxidase led to the fabrication of a glucose biosensor

with excellent performance (Figure 2).

Figure 2. Amperometric biosensor response of

P(HKCN)/GOx, P(EDOT-PdBPI)/GOx,

P(EDOT-PdBPI-co-HKCN)/GOx

Acknowledgments: This work was supported by

TÜBİTAK (Project Number: 115Z555).

References

[1] I-S. Tamgho, J. T. Engle, C. J. Ziegler, Tetrahedron Lett., 2013,

54, 6114-6117.

[2] M. K. Şener, U. Avcıata, J. Chem. Research, 2007, 3, 138-140.

[3] R. Csonka, G. Speier, J. Kaizer, RSC Adv., 2015, 5, 18401-18419.

[4] M. K. Şener, T. Yazıcı, A. Koca, 18. JCF-Frühjahrssymposium, Book of Posters, 2016, 222.

[5] H. C. Söyleyici, M. Ak, Y. Şahin, D. O. Demirkol, S. Timur, Mater. Chem. Phys., 2013, 142, 303-310.



Graphene/nafion nanocomposite based electrochemical biosensor for detecting

Hypoxanthine

M.Kurtulgu

1,2* and S.Çete

3

1Institue of Natural Sciences, University of Gazi/ 2Department of Basic Science, Turkish Military Academy

3Department of Chemistry, Gazi University, Ankara, Turkey


1. Introduction

Graphene (GR), emerging as a true two-dimensional material, has received increasing attention due to its

unique physicochemical properties such as high surface

area (2630 m2g-1), excellent conductivity (200.000

cm2V-1s-1 for single layer), high mechanical strength,

and ease of functionalization and mass production. [1]

Xanthine mainly act to oppose the actions of the

sleepiness-inducing adenosine, and increase alertness in

the central nervous system. They also stimulate the

respiratory center, and are used for treatment of infantile

apnea. Due to widespread effects, the therapeutic range

of xanthine’s is narrow, making them merely a second-line asthma treatment. Also increasing the amount of

xanthine in tissue increases the risk of heart attack. [2]

The therapeutic level is 10-20 micrograms/mL blood;

signs of toxicity include tremor, nausea, nervousness,

and tachycardia/ arrhythmia. Also hypoxanthine is an

critical metabolite of adenine nucleotide degradation,

which is mainly accumulated in biological tissues .[3]

The level of hypoxanthine is used in the food industry

for evaluating the freshness of fish. So, the

determination of hypoxanthine has considerable

importance for quality control of fish and other

products in the food industry.[4]

2. Experimental Details

The synthesis of graphene from graphite was performed

according to the method of Hummer with some

modifications. [5] GR/PtNPs was synthesized from graphene oxide using single-step reduction method with

some modifications. [6] The quantification of xanthine

can be achieved via electrochemical detection of the

enzymatically released H2O2. The immobilization of

xanthine oxidase (XO) has been achieved by cross-

linking with glutaraldehyde. The performances of the

biosensor have been investigated by electrochemical

method at an optimum potential of +0.6 V in pH 8.0

phosphate buffer. All the electrochemical measurements

were performed with a conventional three-electrode

system.

3. Conclusion

There are many reports regarding the electro catalytic

activity of graphene based sensors for the applications

of H2O2. Some of them are listed in Table1. In our study

xanthine biosensor based on immobilization of XO in Pt

nanoparticles/ graphene/ nafion nanocomposite film is responsive to a low concentration of H2O2 (~5µM) and

two different linear determination ranges of 10-5

-10-4

M

and 10-3-10-1 M with R2= 0,999 and R2= 0,967

respectively. According to literature our sensor has low

detection limit and long linear range among to other

studies with good R2 values. This property shows us our

sensor is good candidates for biosensor applications.

Table–1 Comparison of the performance of H2O2 sensor

Potential (V)

Linear range Limit of detection

Ref.

−0.3 100 μM to 100 mM 31.3 μM [7]

−0.3 0.10–50 mM 4 μM [8]

−0.05 20 μM to 0.2 mM 1.9 μM [9]

−0.4 20 μM to 6.25 mM 2.5 μM [10]

−0.4 20 μM to 2.1 mM 9.4 μM [11]

+0.6

I.10 μM to 100 μM

II.1 mM to 100 mM

5 μM This

work

References

[1] Yuyan Shao, Jun Wang, Hong Wu, Jun Liu, Ilhan A. Aksay, Yuehe Lin,

Electroanalysis 2010, 22, No. 10, 1027 – 1036

[2] Bhagavan N.V, Xanthine oxidase reaction Medical Biochemistry,652-

654,1990.

[3] Zhang , J. ; Lei , J. ; Pan , R. ; Xue , Y. ; Ju , H. Biosens. Bioelectron. 2010 ,

26 , 371 .

[4] Hernandez-Cazares , A. S. ; Aristoy , M. C. ; Toldra , F. Food Chem. 2010 ,

123 , 949 .

[5] W.S.Hummers, R.E.Offeman, Preperation of graphitic oxide,

J.am.Chem.Soc.80 (1958) 1339

[6] G. Zhiguo, Y. Shuping, L. Zaijun, S. Xiulan, W. Guangli, F. Yinjun, L.

Junkang. Chim. Acta, 701 (2011), p. 75

[7] S. Liu, J.Q. Tian, L. Wang, X.P. Sun. Carbon, 49 (2011), p. 3158

[8] R. Ning, W.B. Lua, Y.W. Zhang, X.Y. Qin, Y.L. Luo, J.M. Hu, A.M. Asiri,

A.O. Al-Youbi, X.P. Sun Electrochimica Acta, 60 (2012)

[9] E. Jin, X.F. Lu, L.L. Cui, D.M. Chao, C. Wang Electrochimica Acta, 55

(2010), p. 7230

[10] X.X. Liu, H. Zhu, X.R. Yang Talanta, 87 (2011), p. 243

[11] S. Woo, Y.R. Kim, T.D. Chung, Y. Piao, H. Kim Electrochimica Acta, 59

(2012), p. 509


https://en.wikipedia.org/wiki/Adenosine

https://en.wikipedia.org/wiki/Central_nervous_system

https://en.wikipedia.org/wiki/Therapeutic_range


Layer-by-layer Films of Polydopamine and Gold Nanoparticles

G. Bakirci Dündar1, M. Yilmaz1,2* and Gokhan Demirel1

1Bio-inspired Materials Research Laboratory (BIMREL), Department of Chemistry, Gazi University 2 Department of Bioengineering, Sinop University

*Presenter:

Introduction

Many practical applications of coinage metal

nanoparticles strongly depend on their optical

properties, arising from localized surface plasmon

resonances (SPRs). The SPRs can be tuned by varying

parameters such as size and shape of nanoparticles,

dielectric environment (refractive index of

medium/solvent and of coating shells), and interparticle

distance. Recently, the layer-by-layer (LbL) technique

has been proposed as a versatile, easy, and inexpensive

bottom-up nanofabrication technique for the preparation

of nanoparticle-containing ultrathin multilayer films. By

employing this technique, individual and collective SPRs can be created from intralayer or interlayer

interparticle interactions. However, in most cases the

LbL technique usually necessitates the deposition of

oppositely charged polyelectrolytes on substrates. This

issue leads to complicated and time-consuming process,

limiting their use in practical applications.In this study,

to overcome the major drawbacks of nanoparticle-

containing LbL thin films, we proposed gold

nanoparticle-containing (AuNP) films of polydopamine

(PDOP) through oxidative polymerization of dopamine.

Seminal work by Messersmith and co-workers depicted that PDOP can bedeposited on almost all types of

inorganic and organic substrates with easily controllable

thickness, robust stability, and excellent

biocompatibility and as a result of its functional groups

including catechol, amine and imine, metallic

nanoparticles may be easily formed in situ in a

controlled manner without the use of any additional

reductants or metallic seed particles [1]. To this end, the

substrates were immersed sequentially into dopamine (2

mg/ml in Tris-buffer) and chloroauric acid (0.1 mg/ml)

solutions until the creation of desired multilayer films.

Surface enhanced Raman spectroscopy (SERS) of the relevant films were investigated in detail.


According to our previous study, we set the PDOP deposition time as 3 h to form an approximately 10 nm-

thick layer and 12 h for the in situ growth of AuNPs [2].

As shown in Fig. 1, it is observed that the density and

average size of the deposited AuNPs were dramatically

changed with the number of layers. When the number

of layers increased in the fabricated films, the size of the

AuNPs also increased, and average particle size ranged

from 30 nm to 110 nm for the (PDOP/AuNP)2 film and

from 40 nm to 120 nm for the (PDOP/AuNP)3 film. In

UV-vis spectra of films strong absorption peak maxima

were found in the range of 532–572 nm. The emergence

of multilayer films lead to obvious red-shifting and broadening, along with increased absorbances due to

collective SPR characteristics of AuNP-containing

multilayer films with a proper interparticle distance.

Figure 1 Top and cross-section SEM micrographs of (PDOP/AuNP)n LbL films for different layer (n) numbers: n . 1 (a, d), n . 2 (b, e) and n . 3 (c, f), and UV-visible absorption spectra of (PDOP/AuNP)n LbL thin films (g) [3].

In SERS studies (Fig. 2), for the multilayer

(PDOP/AuNP)2 and (PDOP/AuNP)3 films, additional

SERS enhancement was observed compared to the

single layer film ((PDOP/AuNP)1). In those cases, the collective SPR between nanoparticles within adjacent

layers was mainly responsible for the generation of hot

spots with extremely high electric field enhancement.

Figure 2 (a) Representative SERS spectra of methylene blue (MB) on the (PDOP/NP)n LbL thin films with different layer (n) numbers (n . 1, n . 2, and n . 3) and (b) reproducibility of SERS spectra of MB collected on 30 randomly selected spots of (PDOP/AuNP)3 LbL thin films [3].

References

[1] Lee et al. Science, 2007, 318, 426–430.

[2] Akin et al. J. Mater. Chem. B, 2014, 2, 4894–4900.

[3] Yilmaz et al. RSC Adv., 2016, 6, 12638–12641.



Rosmarinic acid modified screen-printed electrode for NADH sensor

M. Bilgi1,2, E.M. Sahin2* and E. Ayranci2

1 Department of Chemistry, Çankırı Karatekin University, Çankırı, Turkey

2 Department of Chemistry, Akdeniz University, Antalya, Turkey


Abstract

Rosmarinic acid (RA) is a hydroxycinnamic acid

derivative and a naturally occurring phenylpropanoid

that is commonly found in species of the Boraginaceae

family, the subfamily Nepetoideae of the Lamiaceae

family, and in lower plants such as ferns and hornworts.

The antioxidants are redox agents, and both

electrochemical and chemical oxidations of these

compounds have been studied [1]. Dehydrogenase

based biosensor need nicotinamide adenine dinucleotide

(NAD+) as a coenzyme. Reduced form NADH generated in the enzymatic reaction is oxidizing on the

electrode surface at suitable potantial and

electrooxidation of NADH is detected. Electrooxidation

of NADH at high overvoltage causes irreversible

formation of enzymatically inactive forms of NAD+ and

contamination (fouling) of electrode surface due to

adsorption of these products which results in

background currents leading to interferences in real

samples. In order to decrease the high overpotential and

to minimize the side reactions, various mediators,

polymers and nanomaterials (NMs) have been widely used in modification of electrodes [2]. The main aim of

the present research is used by RA as new redox

material to the electrooxidation of NADH at lower

potential. As the sensor application of RA modified

SPCE is utilized determination of NADH.

RA was deposited on SPCE by potential cycling

between -0.1 to +0.8 V for 5 cycles in at a scan rate of

20 mV s-1 a solution containing 1 mM RA, 50 mM pH

7.0 PBS. Figure 1 represents the cyclic voltammograms

of 1 mM NADH and buffer obtained with SPCE/RA. The cyclic voltammograms were obtained in a series of

concentrations of NADH and are given in Figure 2. The

anodic current was an enhancement with the addition of

NADH. NADH was detected amperometrically by

applying a potential of +0.25 V (vs. Ag pseudo

reference electrode). Measured current plotted vs

NADH concentration gave a sensitivity and a

correlation coefficient of 8.82 μA.mM-1 and 0.991,

respectively.

Figure 1. CVs obtained with SPCE/RA at a

scan rate of 50 mV s-1 in 50 mM pH 7.0 PBS

(in 0.1 M KCl) containing no NADH (inner

CV) and containing 1 mM NADH (outer CV)

Figure 2. Dependence of CVs response on

NADH concentration for a SPCE/RA in in 50

mM pH 7.0 PBS (in 0.1 M KCl) at 50 mV s-1.

NADH concentrations are 0.1, 0.25, 0.50,0.75,

1.0, 1.5, 2.0, 3.0, 5.0 mM from inner to outer

cycles, respectively.

References

[1] Park, S.U.; Uddin, M.R.; Xu, H.; Kim, Y.K.; Lee,

S.Y.; Afr. J. Biotechnol., 2008, 7, 4959-4965.

[2] Sahin, M.; Ayranci, E., Electrochimica Acta 166

(2015) 261–270.

-15

-5

5

15

25

-0,1 0,1 0,3 0,5

Cu

rren

t/µ

A

Potential/V

-10

0

10

20

30

40

-0,1 0,1 0,3 0,5

Cu

rren

t/µ

A

Potential/V



The Comparison of the Development and Performance of The Biosensor

For Determination of Aminoglycoside Antibiotics In Animal Products On

The Ultrasensitive Aptamer Based Biosensor

Mert Muhammed Koc1*

, Merve Kucukoflaz1, Yagmur Guler

1, Şengül Kurtuluş and Mustafa Oguzhan Caglayan

1

1Nanotechnology Engineering Department, Cumhuriyet University, Sivas, Turkey


1. Introduction

Antibiotics bacteria are chemical compounds that kill or

slow their growth and are useful in treating bacterial

infections. But it consist of a danger as the development

of resistant bacteria against that antibiotic use excessive

or unnecessary use of the drug, Taken together with

residual nutrients consumed through the food chain

antibiotics, super bacteria to form and cause damage to

organs such as the liver and kidney. Therefore,

monitoring of residual levels of antibiotics in the food

chain is important is also a necessity. Also, aminoglycoside antibiotics are ototoxic in terms of

human health and nephrotoxic. Therefore, environ

mental monitoring of antibiotic levels including food

waste, will reduce the risk of forming dangerous multi-

drug resistant strains of bacteria.


Aminoglycoside antibiotics are ototoxic in terms of

human health and nephrotoxic. Therefore also including

your food remnants, the environ mental monitoring of

antibiotic levels will reduce the risk of developing drug-

resistant bacteria at multivariate dangerous species. İn

many countries in terms of contamination with antibiotics, such as kanamycin and neomycin, are

controlled foods of animal origin. The limit until they

are admitted, on the kanamycin 150ng/ml, and

streptomycin for 500ng/ml, and neomycin for 500ng/ml.

Therefore, the animal source of the determination of

antibiotic residues in foods on the new method are

targeted to improve access. Due to the high affinity of

the aptamers show, kanamycin and neomycin, based on

the aptamer and spectroscopic ellipsometry (SE) and

fortified by surface plasmon resonance - sincere

biosensor was developed using the methods of the full reflection ellipsometry (SPRe-TIRE). Quite different

from each other on the use of specified methods to

optimize both the immobilization has been carried out

of route conditions.


In this study, toxic effects should both be in the food

chain due to the accumulation and transfer super-

bacteria that can cause it to form aminoglycoside groups

are apta-sensor been implemented with the appointment

of two antibiotics. Aptasensor target is measured can be

converted to form the actual phisicochemical caught

after the change has been preferred on the ellipsometry which will be used as a converter. Ellipsometric round

of two different techniques, spectroscopic ellipsometry

and sincere exact reflection (TIRE) are

compared. When used because the techniques are

slightly different from the sensor surface were followed

two different paths immobilization. Silicon flakes and

gold coated glass slide surface immobilization methods

of the specified aptamer groups on the optimized obtain

this study, the target, the other can compete with

antibiotics residual analysis techniques and the

development of an unlabeled detection methods.

Kanamycin or neomycin using such study presented on

the spectroscopic ellipsometry and ellipsometry sincere

exact reflection of two different types of sensors have

been developed and compared. Such study used all

aptamers and SE with SPRe - TIRE sensors are nearly gave similar analytical results. Determination of the

lowest limit of the kanamycin on the 100 pM, the

highests interest of 4.00 nM, all sensors in the

determination of possible limit there has been between 1

uM. for neomycin lowest LOD 360 pM, the highest

has be 6.88 nM.

Table 1 selectivity of the sensor (For SE)

Sensor Response (Δ)

Aptamer Tobramycin

(not avaible)

Tobramycin

(available)

Tobramycin

(purely)

AntiKnm3 4.3068±0.057 4.6083±0.087 0.3015±0.100

AntiNeo5 4.8776±0.087 5.0727±0.131 0.4389±0.116

Table 2 selectivity of the sensor (For SPRe-TIRE)

Sensor Response (Δ)

Aptamer Tobramyci

n (not

avaible)

Tobramyci

n

(available)

Tobramycin

(purely)

AntiKnm

1

7.4985±0.0

70

8.5337±0.13

4

0.2481±0.09

2

AntiNeo1 6.49622±0.

134

8.6066±0.22

9

0.60660±0.1

48

It should be noted, the connection of the sensor

structure must be a straight answer measure. Therefore

offered ranges, are expressed as a range measure. The

result between the detection limit of the working range,

the lowest detection limits obtained in this study,

working in a relatively narrow range of enumeration.

Obtained sensor performance, although kanamycin and neomycin the under limit of the (500ng/ml) wich

designated the clipboard, at the same time, kanamycin

and neomycin on reported ELİSA method based,

when compared (respctively 0.83ng/mL and 2.73ng

/mL) are compared inside limits.



Investigation of the use of Periodic Nanobump Surfaces for Detecting Myoglobin

Protein

Merve Çelik1*, Sevde Altuntaş1 and Fatih Büyükserin2

1 Biomedical Engineering Graduate Program, TOBB University of Economics and Technology, Ankara, Turkey 2 Department of Biomedical Engineering, TOBB University of Economics and Technology, Ankara, Turkey


Abstract

Acute myocardial infarction is the most common cause

of mortality worldwide.[1] Because of the difficulties of

distinguishing the physical symptoms and the need for

urgent medical intervention, early diagnosis of this

disease is crucial. Apart from the physical symptoms of

acute myocardial infarction, abnormalities in the ST

segment of electrocardiogram of the patient and the

concentration of some proteins like myoglobin which

starts to be secreted 1 hour after the symptoms and

troponin which starts to be secreted 3-6 hours after the symptoms is the markers of this disease.[2] Current

protein detection methods like ELISA and

electrophoresis are high-cost and requires expertise.[3] It

is crucial to design a simple and ultra sensitive protein

detection method for early diagnosis in order to increase

the survival rate of the patients and overcome the

problems mentioned.

Surface-enhanced Raman spectroscopy (SERS) is a

powerful technique used for molecular analysis that

provides molecular fingerprint information and has the

potential to detect down to single molecule.[4] Despite

the ultra sensitivity and specificity of this technique,

SERS can not be used as a routine sensing tool.[5] This

is because of the poor reproducibility of SERS signals.

In order to provide highly reproducible SERS signals,

reproducible strong SERS-active substrates should be

designed.

Properties of an ideal SERS substrate are stated in

previous researches.[5] The most important properties

are high signal enhancement and signal reproducibility

which periodic nanostructured arrays satisfy. In the

current studies these periodic nanostructures are usually

created by lithography.[6] But this technique is time consuming, high cost and can not be applied to large

surface areas.

In the proposed system, nanostructured anodic

aluminum oxide (AAO) membranes are used for SERS

signal enhancement. These membranes are a class of

special biomaterials that are produced from high purity aluminum via two step anodization methods. The

production of the substrates are easy and highly

controllable with this method and compared to

lithography it is cost-effective. It is possible with this

procedure to produce AAO membranes with different

column structures and thicknesses depending on voltage

and anodization time. The produced membranes are

used aluminum-free and the nanobumpy barrier side of

the membrane is used as the SERS platform. Then this

barrier side will be treated with acidic solutions to form

crater on the surface to create a different surface

topography with potentially enhanced SERS signals as

predicted with previous simulations.

Figure 1 SEM images of the produced images

nanobumpy array(left), nano crater array (right)

The prepared surfaces will be modified with Au and the

Raman-active dye, Rhodamine 6G. SERS signal

enhancements of the surfaces will be determined. In the

last part of this study protein detection will be

performed with the surface that has the highest signal

enhancement. As the earliest biomarker of acute

myocardial infarction, in order to achieve early

diagnosis myoglobin will be detected on this biosensing

platform.

References

[1] Straface, Angela L., et al. "A rapid point-of-care cardiac

marker testing strategy facilitates the rapid diagnosis and management of chest pain patients in the emergency department." American journal of clinical pathology 129.5 (2008): 788-795. [2] Newby, L. Kristin, et al. "Value of serial troponin T measures for early and late risk stratification in patients with acute coronary syndromes." Circulation 98.18 (1998): 1853-1859. [3] Sharma, Vikash, et al. "Electrochemical impedance

immunosensor for the detection of cardiac biomarker Myogobin (Mb) in aqueous solution." Thin Solid Films 519.3 (2010): 1167-1170. [4] Choi, Dukhyun, et al. "Self Organized Hexagonal Nanopore SERS Array." Small 6.16 (2010): 1741-1744. [5] Cialla, Dana, et al. "Surface-enhanced Raman spectroscopy (SERS): progress and trends." Analytical and bioanalytical chemistry 403.1 (2012): 27-54.

[6] Banholzer, Matthew J., et al. "Rationally designed nanostructures for surface-enhanced Raman spectroscopy." Chemical Society Reviews 37.5 (2008): 885-897.



Determination of Spread-Based Biosensor TIRE Multiprecision micropatterned,

and Development of Oligonucleotide and Protein Immobilization Method for

Chip and the Sensor Performance

Merve Kucukoflaz1*, Mert Muhammed Koc1 , Şengül Kurtuluş1 ,Yagmur Guler1 and Mustafa Oguzhan Caglayan1


* Presenter: [email protected]

1. Introduction

Biosensors provide reliable and quick response analysis

achieved with the combination of appropriate

transducers and utilization of selectivity and specifity of

bioaffinity. However, it is required, the reactions those

are fast and selective, occuring on biosensors, to be

defined quickly with the same accuracy. Surface

plasmon resonance (SPR) and ellipsometry based on

optical transducers provide an accurate and an on-line

analysis. In this study, development of a micro-

patterned biosensor system available for multiple and

qualitative/quantitative determination of one or more

bio-molecules with a single and modified biosensor chip which implements both of total internal reflection

ellipsometry and surface plasmon resonance techniques

was aimed.


In the first step, a multiple step micro-patterning was

applied on designed biosensor chip, then, self assembled

monolayer was formed by using various chemical

methods on micro-patterned biosensor chip, and finally

by using “layer by layer” approach, appropriate probes

selected from bio-affinity pairs were immobilized on

formed monolayers. For this purpose, these steps were performed, briefly: (a) combination of surface plasmon

resonance technique and total internal reflection

ellipsometry; (b) application of different metal films

yielding surface plasmon resonance phenomena on

same chip surface; (c) micro-patterning of surface

plasmon resonance enchanted (SPRe) total internal

reflection ellipsometry (TIRE) sensor chip; (d)

application of appropriate modification on micro-

patterned chip surface by layer by layer approach; and

(e) evaluation of performance of produced sensor chip.

This project consists of 4 work packages (IPs). In the

IP1, substrate preparation for sensor chip and micro-patterning of this chip surface by photolithography

technique were performed. In the IP2, micro-patterned

chip substrate was functionalized by using protective

and multi-step modification method. Oligonucleotide

probe which has specific sequence for Avian Influenza

(H1, N1) and Protein A probe were immobilized on to

functionalized micro-patterns to get a specific pattern

(IP3). Finally, performance of designed sensor chip on

SPRe-TIRE configuration was evaluated. At this step,

sensor signal was acquired against reaction duration,

while complementary ODN (target) and H-IgG (target) molecules are interacted with the sensor chip under

certain conditions. Bio-molecular determination was

realized in a short time and with small concentrations of

target; by using the advantages of SPRe-TIRE

phenomena and detection limit decrement using

appropriate sensor chip design giving SPR.


In this study, avian influenza (bird flu) Influenza A

group pathogen assay for the gradual immobilization

techniques of a sensor that can run as simultaneous

protein sensor with synthetic ODN-based sensor

micropattern that eseasl array (array) structure has been

developed.

Protein-protein interactions based on protein A-IgG

interaction is modeled for the second micropattern

Detection limits for IgG was determined to be 80 nM.

Both sequences in 100 minutes on the same chip and

ODN target protein produced a signal that reaches

equilibrium.In addition, the sensor only when used for

on-off signal of the chip (on a signal to noise ratio) and ODN as well as the time appointed for the target protein

is around 30 minutes.for InfA

Figure 1 – 2B- Ellipsometric image of the micro-

patterned substrat

es

Figure 2 – IgG- interaction of Protein A sensor

response.



Evaluation of Methods for the Detection of Oxygen in

Packaged Food Products

Meryem Yılmaz

1*, Elif Atay

1 and Aylin Altan

1

1Department of Food Engineering, Mersin University, Mersin, Turkey


Abstract

Detection of oxygen is very important to packaged food products. Food has respiration capability and the gas

composition in the package can change as a result of

interaction of food with its environment [1]. Therefore,

oxygen in the gas composition can be one of the main

cause of food spoilage, resulting in aerobic microbial

growth, oxidation of food components such as lipids

and micronutrients, and changes in color, flavor, bad

smell, etc [2]. Therefore, intensive studies have been

made to develop oxygen sensors and oxygen indicators

which can simply detect oxygen gas. In contrast to

oxygen sensors which are able to detecting oxygen

molecules and transforming the detecting information into electrical signals in a quantitative manner, oxygen

indicators are described as devices that enable people to

recognize changes in the optical absorbance of organic

dyes or pigments according to the oxygen concentration

in the form of changes in color in a semi-quantitative or

a rather qualitative manner. Therefore, oxygen

indicators can offer many advantages over oxygen

sensors due to their impregnability from electrical and

electromagnetic interferences, strength, tiny size and

their low expense [3]. One of the established method for

the detection of oxygen, fluorescent-based oxygen sensors have been used to remote measurement of

headspace gases inside packaged products. Sensors

designed in this study normally have been taken place a

fluorescent or phosphorescent dye encapsulated in a

solid polymer matrix and added to a suitable support

material. If there are molecular oxygen in the packaged

products, it quenches the luminescent dye and can be

quantified against predetermined calibrations. The

process is reversible and there are not side products [4].

Another method used for the detection of oxygen is

colorimetric method. With colorimetric method,

methylene blue based on the nafion film has been prepared and chemical reactions in contact with active

oxygen species have been estimated. Methylene blue

used for colorimetric oxygen indicator has been

preferred for that one of redox dyes. Therefore, in this

study, decolorization mechanism of the film due to

exposure of the active oxygen species has been

discussed [5].

Other method used for the detection of oxygen, UV-

activated oxygen indicator has been developed by using

electrospinning in this study. By dispersing TiO2

nanoparticles, glycerol and methylene blue in poly ethylene oxide solution using aqueous ethanol as a

solvent, the oxygen indicator has been prepared. As a

result, this study showed that TiO2-based indicator has

been promising for oxygen detection in modified

atmosphere packaging applications [6]. There are many established methods for the detection of

oxygen, involving colorimetric, fluorescent and

conductivity methods, however, such instruments are

costly, required trained users to operate, lack of

portability and time consuming to allow full quality

assurance. Therefore, there is an increasing interest in

cheap and simple developments today for using oxygen

indicators [6-7].

In recent years electrospinning method is an open for

improvement and popular technology because it offers

advantages such as control over morphology, porosity

and composition by using simple equipment. Nowadays, this method can be used for production of

biosensors to detect of oxygen in packaged products.

References

[1] De Jong, A.R., Boumans, H., Slaghek, T., Van

Veen, J., Rijk, R., Van Zandvoort, M. 2005. “Active and

intelligent packaging for food: Is it the future?” Food

Additives & Contaminants, 22: 975-979.

[2] Vermeiren, L., Devlieghere, F., Van Beest, M., De

Kruijf, N., Debevere, J. 1999. “Developments in the

active packaging of foods”, Trends in Food Science

Technology, 10:77-86. [3] Sumitani, M., Takagi, S., Tanamura, Y., Inoue, H.

2004. “Oxygen Indicator Composed of an

Organic/Inorganic Hybrid Compound of Methylene

Blue, Reductant, Surfactant and Saponite”, Analytical

Science, 20: 1153-1157.

[4] Hogan, S.A., Kerry, J.P. 2008. “Fluorescent Based

Oxygen Sensors”, In Smart Packaging Technologies for

Fast Moving Consumer Goods.

[5] Iwamori, S., Nishiyama N., Oya, K. 2015. “A

colorimetric indicator for detection of hydroxyl radicals

in atmosphere using a methylene blue dye based on

nafion film”, Polymer Degradation and Stability, 123:131-136.

[6] Suramya, D. F. Mihindukulasuriya, Loong-Tak, L.

2013. “Oxygen detection using UV-activated

electrospun poly (ethylene oxide) fibers encapsulated

with TiO2 nanoparticles” Journal of Materials Science,

48: 5489-5498.

[7] Wolfbeis, O. S. 1991.“Fibre Optic Chemical Sensors

and Biosensors”, CRC Press.



Sensitive detection of Melanoma-associated antigen by regenerative

immunosensor based on ITO modified with self-assembled silane

monolayers

Aslı Gündoğdu1, Münteha Nur Sonuç Karaboğa

2,3* and Mustafa Kemal Sezgintürk

1

1 Department of Chemistry, Namik Kemal University, Tekirdag, Turkey

2 Department of Chemistry , Institute of Science, Namik Kemal University, Tekirdag, Turkey 3 School of Health, Namik Kemal University, Tekirdag, Turkey


1. Introduction

Melanoma-associated antigens (MAGE), a group of

well-characterized members of the Cancer/testis

antigens (CTA) family. The MAGE family has been

divided into two big categories: MAGE-I and MAGE-II

based on their tissue-specific gene expression and

chromosomal location. [1-2] Most of them are highly

expressed in various forms of cancer, normally

expressed in testis, trophoblast, and placenta. [3] Since

MAGE antigens are strictly tumor-specific, they have

the potential to become the ideal targets for cancer immunotherapy. [4] To date, the protein expression of

the MAGE family and their correlation with clinico-

pathological characteristics has been carried out in

various solid tumors including hepatocellular

carcinoma, lung cancer , renal cell carcinoma, epithelial

ovarian cancer , gastric and colorectal cancers , and

lymphoma. In addition, a larger cohort exploration

concerning MAGE expression was also performed in

head and neck squamous cell carcinoma (HNSCC). [5]

From this view, present study aimed to a novel,

disposable and, cost-effective immunosensor based on

indium tin oxide (ITO) sheets modified with silane

chemistry to selectively analyze MAGE-1, a potentional

biomarker.


In present study, the novel and simple biosensor system was developed to detect MAGE. Carboxyethyl silane

etriol was used firstly as a self assembled monolayer

agent. The activation of -COOH groups was carried out

using 1-ethyl-3-(3-dimethylaminopropyl) carbodimide

(EDC) /N-hydroxysuccinimide (NHS) couple.

Analytical characteristics of constructed biosensor such

as square wave voltammetry, linear determination range,

repeatibility, reproducibility and regeneration of

biosensors are determined. All characteriation steps are

monitored by electrochemical impedance spectroscopy

(EIS) and cyclic voltammetry (CV). The presented biosensor has wide determination range (0.004 pg/mL-

0.2 pg/mL). To investigate long shelf life of the

fabricated biosensor, the immunosensors were stored at

4°C for periods ten weeks. Beside, binding kinetics of

MAGE to anti-MAGE is monitored by single frequency

technique in real time. Moreover, Kramers Kronig

transformations were performed for validation of

obtained EIS data in all steps of biosensor fabrication.

In the end, the presented biosensor was performed to

real serum and compared with standart literature

findings. Morphological characteristics of constructed

biosensor were observed by scanning electron

microscopy (SEM).

Consequently, the present biosensor system has

significant advantages and these biosensor give hope in

terms of applicability in clinical diagnosis of some

cancer types.

Acknowledgement: Support from TÜBİTAK (The


Turkey, Project number: 113 Z 678) is greatly

acknowledged.

References

[1] Xu X, Tang X, Lu M, Tang Q et al., Exp Mol

Pathol. 2014, 97(3):579-84

[2] Sang M1, Wang L, Ding C, Zhou X, Wang

B, Cancer Lett. 2011 Mar 28;302(2):85-90

[3] Achim A. Jungbluth, Wilson A. Silva, Jr., Kristin

Iversen, Denise Frosina Cancer Immun. 2007; 7:

15.

[4] Nathalie Vigneron, Biomed Res Int. 2015; 2015:

948501

[5] Achim A. Jungbluth, Klaus J. Busam , Denise

Kolb International Journal of Cancer Volume

85, Issue 4, pages 460–465


http://www.ncbi.nlm.nih.gov/pubmed/?term=Xu%20X%5BAuthor%5D&cauthor=true&cauthor_uid=25445503

http://www.ncbi.nlm.nih.gov/pubmed/?term=Tang%20X%5BAuthor%5D&cauthor=true&cauthor_uid=25445503

http://www.ncbi.nlm.nih.gov/pubmed/?term=Lu%20M%5BAuthor%5D&cauthor=true&cauthor_uid=25445503

http://www.ncbi.nlm.nih.gov/pubmed/?term=Tang%20Q%5BAuthor%5D&cauthor=true&cauthor_uid=25445503

http://www.ncbi.nlm.nih.gov/pubmed/25445503


http://www.ncbi.nlm.nih.gov/pubmed/?term=Sang%20M%5BAuthor%5D&cauthor=true&cauthor_uid=21093980

http://www.ncbi.nlm.nih.gov/pubmed/?term=Wang%20L%5BAuthor%5D&cauthor=true&cauthor_uid=21093980

http://www.ncbi.nlm.nih.gov/pubmed/?term=Ding%20C%5BAuthor%5D&cauthor=true&cauthor_uid=21093980

http://www.ncbi.nlm.nih.gov/pubmed/?term=Zhou%20X%5BAuthor%5D&cauthor=true&cauthor_uid=21093980

http://www.ncbi.nlm.nih.gov/pubmed/?term=Wang%20B%5BAuthor%5D&cauthor=true&cauthor_uid=21093980

http://www.ncbi.nlm.nih.gov/pubmed/?term=Wang%20B%5BAuthor%5D&cauthor=true&cauthor_uid=21093980


http://www.ncbi.nlm.nih.gov/pubmed/?term=Jungbluth%20AA%5Bauth%5D

http://www.ncbi.nlm.nih.gov/pubmed/?term=Silva%20WA%5Bauth%5D

http://www.ncbi.nlm.nih.gov/pubmed/?term=Iversen%20K%5Bauth%5D

http://www.ncbi.nlm.nih.gov/pubmed/?term=Iversen%20K%5Bauth%5D

http://www.ncbi.nlm.nih.gov/pubmed/?term=Frosina%20D%5Bauth%5D

http://www.ncbi.nlm.nih.gov/pubmed/?term=Vigneron%20N%5Bauth%5D


Hydrodynamic Trapping of Micro-Liter Droplets and Biological Samples

Adil Mustafa1, Nima Bavili*1, Melikhan Tanyeri2, Ahmet Erten3 , Alper Kiraz1

1 Department of Physics, Koç University, İstanbul, Turkey 2 Department of Electrical Engineering, Özyeğin University, İstanbul, Turkey

3 Department of Electrical Engineering, Osmaniye University, Osmaniye, Turkey


1. Introduction

Hydrodynamic trapping has been introduced recently as

a powerful tool for trapping and manipulation of micro

beads, DNA molecules, cells or generally any

micron/nano sized particles. The technique finds its

novelty in its non-contact based trapping.

2. Experiments

One of the major and most recent applications of this

method is investigating the dissolution of liquid micro

droplets in aqueous solutions [1]. One parameter characterizing the dissolution is diffusion coefficient or

in other terms, mass transfer coefficient. Diffusion

coefficient is an important parameter for industrial

applications such as separation/sorting processes and

drug delivery/design [2-4]. Work is under progress on

implementing hydrodynamic trapping method for

biological samples such as RBC. Experiments are also

being performed on measuring deformation of

hydrodynamically trapped low surface tension micro

droplets, which is also applicable to biological samples.

3. Results

We have observed the dissolution using micro droplets

of benzyl benzoate and n-decanol trapped in water and

surfactant (DSS) solution at different flow rates. The

results show that rate of dissolution of micro droplets increases at high flow rates. The rate of dissolution also

changes from benzyl benzoate to n-decanol with

ndecanol dissolving faster than benzyl benzoate. The

results also showed that dissolution also is affected by

amount of surfactant in the solution. Obtained data from

experiments were analyzed and used to modify the

Epstein-Plesset equation [5].

References

[1] A. Mustafa, A. Erten, R. M. A. Ayaz, O.

Kayıllıoğlu, A. Eser, M. Eryürek, M. Irfan, M.

Muradoglu, M. Tanyeri, and A. Kiraz, Enhanced

Dissolution of Liquid Microdroplets in the Extensional

Creeping Flow of a Hydrodynamic Trap. Langmuir, 2016, 32 (37), pp 9460–9467

[2] Duncan, P. B.; Needham, D. Microdroplet

dissolution into a second-phase solvent using a

micropipet technique: test of the Epstein-Plesset model

for an aniline-water system. Langmuir 2006, 22,

4190−4197.

[3] Harland, R. S.; Gazzaniga, A.; Sangalli, M. E.;

Colombo, P.; Peppas, N. A. Drug/polymer matrix

swelling and dissolution. Pharm. Res. 1988, 5, 488−494.

[4] O’Donnell, P. B.; McGinity, J. W. Preparation of

microspheres by the solvent evaporation technique. Adv. Drug Delivery Rev. 1997, 28, 25−42. [5] Epstein,

P.; Plesset, M. On the Stability of Gas Bubbles in

Liquid-Gas Solutions. J. Chem. Phys. 1950, 18,

1505−1509.



Determination of protein activated kinases 2 (PAK 2) by a sensitive

electrochemical biosensor

Nergiz Kılınç1* and Mustafa Kemal Sezgintürk1

1 Namik Kemal University, Faculty of Arts and Science, Chemistry Department, Biochemistry Division, Tekirdag,

Turkey


1. Introduction

Among the many different signaling molecules that

regulate cell survival and cell death are the p21

activated protein kinases (PAKs). PAKs are activated in

re

sponse to extracellular signals and regulate cell shape

and motility as well as cell survival and programmed

cell death. The mammalian PAK family consists of six members that can be divided into two subfamilies

according to sequence homology. The first subfamily

consists of PAK-1 (alpha-PAK), PAK-2 (gama-PAK),

and PAK-3 (beta-PAK). PAK-1 and PAK-3 are tissue-

specific with the highest levels in brain, whereas PAK-2

is ubiquitous. The second subfamily consists of the

more recently identified PAK-4, PAK-5, and PAK-6.

p21-activated protein kinases (PAKs) are a family of

serine/threonine protein kinases that are activated by

binding of the p21 G proteins Cdc42 or Rac. The

ubiquitous PAK-2 (gama-PAK) is unique among the PAK isoforms because it is also activated through

proteolytic cleavage by caspases or caspase-like

proteases. In response to stress stimulants such as tumor

necrosis factor alfa or growth factor withdrawal, PAK-2

is activated as a full length enzyme [1]. Silica gel is an

amorphous inorganic polymer composed of siloxane

groups (Si-O-Si) in the inward region and silanol groups

(Si-OH) distributed on the surface. Modification of

silica gel by inorganic or organic functional groups has

been the subject of considerable interest due to many

possibilities of application. Surface modifications are

usually achieved with silanization using an appropriate organosilane agent. One of the most widely applied

organo-functional alkoxysilanes is 3-

glycidoxypropyltrimethoxysilane (3- GPTMS). Its

epoxide groups are convenient for the covalent binding

of enzyme and proteins. The O-C and N-C bonds

formed by the epoxide groups are extremely stable, so

that the epoxide-containing polymers can be used for

the immobilization of enzyme and proteins [2].


In this study, we designed a novel biosensor to detect

PAK-2 biomarker constructed on modified indium tin oxide (ITO) disposable electrodes. Anti-PAK2 was

immobilized through covalent with 3-

glycidoxypropyltrimethoxysilane which formed a self-

assembled monolayers (SAMs) on modified ITO

electrodes. Analytical characteristics such as square

wave voltammetry, linear determination range,

repeatibility, reproducibilty and regeneration of

biosensors were determined. All characterization steps

were monitored by Cyclic voltammetry (CV), and

electrochemical impedance spectroscopy (EIS)

techniques. To achieve reproducible and repeatable

biosensor system, all parameters such as SAMs concentration, antibody concentration and antibody

incubation time were optimized. The presented

biosensor has wide determination range (5 fg-75

fg/mL).

Acknowledgement: We are thankful for financial

support from the Scientific and Technological Research

Council of Turkey (TÜBİTAK, Project number: 113 Z

678).

References

[1] Rolf Jakobi, Corine C. McCarthy, Mark A. Koeppel, and Daniel K. Stringer.’’ Caspase-activated PAK-2 Is

Regulated by Subcellular Targeting and Proteasomal

Degradation*.Vol. 278, No. 40, Issue of October 3, pp.

38675–38685, 2003 Printed in U.S.A.

[2] Seung Won Park, Jeewon Lee, Suk In Hong, Seung

Wook Kim.’’ Enhancement of stability of GL-7-ACA

acylase immobilized on silica gel modified by epoxide silanization. Process Biochemistry 39 (2003) 359/366




Preparation of Poly(thionine) Supported Platium Nanoparticles For

Electrocatalytic Applications

N. Çoşkun Kurt1* and M. Sönmez Çelebi1

1Department of Chemistry, Faculty of Science and Arts, Ordu University, 52200, Ordu, Turkey


1. Introduction

Fuel cells are regarded as promising energy sources for

the future to replace the traditional systems which use

fossil fuels. During the operation of a fuel cell, the

chemical energy of the fuel (hydrogen, methanol,

ethanol, formic acid, etc.) and the oxidant (oxygen gas

or hydrogen peroxide) is catalytically converted to

electricity at the active interface regions between the

electrodes and the electrolyte. Fuel is oxidized in the

anode whereas reduction of the oxidant takes place in

the cathode [1,2] The catalyst layer on the electrodes

contains precious (often Pt) or non-precious metal particles which are generally supported on a suitable

material. Pt-based catalysts are used frequently for

construction of both anodes and cathodes while non-

precious metals are generally used in the cathode

compartment. Therefore, electrode materials are of great

importance for increasing the efficiency and reducing

the cost of a fuel cell system. Metal nanoparticles have

interesting and unique properties compared to larger

corresponding metal particles. Metal particles with nano

and uniform sizes have many applications in optics,

electronics, magnetic devices and as catalysts,

photocatalysts, adsorbents and sensors. Generally, the small particle size and high dispersion of metal particles

will result in high electrocatalytic activity [3]. Metal

nanoparticles supported on functional polymers have

many advantages such as generation of metal

nanoparticles with a controlled size and size distribution

and influencing the chemical behavior of metal

nanoparticles via interaction with the polymer bound

functional groups [4]. In the current work, synthesis of

poly(thionine) (PTH)-supported Pt particles on pencil

graphite electrode was described. Pt particles were

incorporated into the polymer matrix via cyclic voltammetric scans in aqueous K2PtCl4 solution without

supporting electrolyte. The Pt complexes immobilized

in the redox polymer matrix were then reduced by

chemical reduction using hydrazine as the reducing

agent. The Pt nanoparticles were tested for

electrocatalytic oxidation of methanol for fuel cell

applications.

2. Experimental

In electrochemical studies, a pencil graphite electrode

(PGE) (r = 0.25 mm) was used as the working electrode.

A saturated calomel electrode (SCE) was used as the

reference electrode and a Pt wire was used as the

counter electrode. Cyclic voltammetry studies were

carried out with CH Instruments System, Model 600E.


Thionine was electrochemically polymerized onto the

PGE surface by cyclic voltammetry from aqueous

solution of TH containing 0.5 M H2SO4 as the

supporting electrolyte. Polymerization profile of PTH is

given in Figure 1.

Figure 1 Polymerization profile of TH

Pt particles were incorporated into the polymer matrix via cyclic voltammetric scans in 2 mM K2PtCl4 solution

without supporting electrolyte. The Pt complexes

immobilized in the redox polymer matrix were then

reduced by chemical reduction using hydrazine as the

reducing agent.

The PTH supported Pt nanoparticles prepared as

described above showed excellent catalytic activity

towards electrooxidation of methanol (Figure 2). It can

be stated that PTH supported Pt nanoparticles can be

used as anode catalysts for direct methanol fuel cells.

Figure 2 CV of 0.5 M methanol + 0.5 M H2SO4

References

[1] J. Yuan, B. Sunden, Int J Heat Mass Tran, 69, 358 (2014)

[2] Y, Wang, K.S. Chen, J. Mishler, S.C. Cho, X.C. Adroher Appl Energ, 88,

981 (2011)

[3] M. Adlim, M.A. Bakar, K.Y. Liew, J. Ismail, J. Molecular Catalysis: A

Chemical, 212, 141 (2004).

[4] M. Kralik and A. Biffis, J. Molecular Catalysis: A Chemical, 177, 113

(2001).



Molecularly Imprinted Electrochemical Sensor for Selective Determination of

Proline

Nihal Ermiş1*, Melike Baskaya and Nihat Tinkiliç1

1 Department of Chemistry, Ondokuz Mayıs University, Samsun, Turkey

*Presenter: [email protected].

tr

1. Introduction

Proline is a very important amino acid because of its

vital role in protein synthesis and structure. Besides it

takes part in wound healing, antioxidative reactions [1].

In general, molecular imprinting method is used via

polymerization of proper monomers around a selected

template. By using an elution agent, template molecules

leave complementary cavities to its three dimensional

structure. On interaction with the imprinted polymer

and template molecule containing solution, via these

cavities polymer behaves as a recognition element. [2] Through mixing this method and electrochemical

techniques, analyte selectivity and specifity can be

gained. In this study, the fabrication of a highly

selective and sensitive proline sensor was investigated

using a polypyrrole (PPy) polymer as an artificial

recognition element. Pyrrole and piroline were used as

the functional monomer and template molecule,

respectively. Electropolymerization on gold electrode

was used to prepare a novel sensor for detecting piroline

without any extra reagent like enzyme or mediator.

2. Experimental

All electrochemical experiments and

electropolymerization were performed on a VersaStat 3

electrochemical system (Princeton Applied System)

connected to a personal computer. The three-electrode

system was consisted of Au (1.6 mm in diameter),

Ag/AgCl/KCl (saturated) electrode and Pt wire, as

working, reference and auxillary electrode, respectively.

The surface of the gold electrode was polished on a

microcloth with 1.0 and 0.05 μm aqueous slurry of alumina. After this it was cleaned in an ultrasonic bath

in water for 5 min to remove any particles on the

surface and then allowed to dry at room temperature.

The electrosynthesis of PPy film was performed by

cyclic voltammetry (CV), between -0.2 and 1.2 V vs.

Ag/AgCl, at a scan rate of 100mV/s. Under same

conditions, without template molecule a non-imprinted

polymer (NIP) was synthesized in order to examine

difference. For electrochemical characterization of MIP

and NIP modified electrode, CV was used.

Electroanalytical measurements were performed with different concentrations of piroline solutions between 1

and 25 nM with square wave voltammetry (SWV)

technique. The selectivity of the imprinted electrode to

tyrosine was evaluated by SWV with the other two

similar molecules, leucine and valine . After template

removal, MIP modified electrodes were immersed in

solutions of this similar molecules

The prepared imprinted sensor was applied for the

detection of piroline levels in honey samples with

standart addition method. Honey was obtained from a

local market. As a comparative study, piroline content in

honey was analysed through Ough method also. The

results were satisfactory.


Electrochemical characterization of MIP electrode was

made via CV technique as seen on Figure 1. Same

technique was also used to show up the difference between NIP and MIP modified electrodes. According

to the results of selectivity analysis, the adsorption

capacity of NIP modified electrode was almost the same

for each molecule while MIP electrode showed higher

selectivity to proline instead of other selected

molecules.

Figure 1 Difference between bare and MIP modified electrode (blue-bare ;red-MIP

electrode)

Consequently a novel sensor which can detect piroline,

in a wide range levels and lower detection limit was

synthesized. According to the results specificity,

sensitivity, reproducibility were also good and through

MIP method higher selectivity and sensitivitiy gained.

References

[1] Wu Guoyao. et al. Proline and hydroxyproline metabolism: implications for animal and human nutrition (Amino Acids. 2011 Apr; 40(4): 1053–1063 [2] Vasapollo G. et al. , Molecularly Imprinted Polymers : Present and Future Perspective, International Journal of Molecular Sciences 12 (2011) 5908-5945

0 0,2 0,4 0,6 0,8

Cu

rren

t (u

A)

Volt (V)



Guanin Signal Enhancement at DNA Biosensor Using Metal Nanoparticules-

Mixed Silica Gel: Application to Hybridization Detection on Biosensor Surface

Nilay Aladag Tanik1*, Elif Demirkan1 and Yakup Aykut2

1 Department of Biology, Uludağ University, Bursa, Turkey

2 Department of Textile Engineering, Uludağ University, Bursa, Turkey


1. Introduction

In this study, we have detected the hybridization electrochemically on the pencil graphite electrode

(PGE) surface and we used to cobalt (Co) nanoparticles

and silica gel for the signal enhancement. For

determining the mutation or polymorphism, RFLP, RT-

PCR, and DNA sequencing methods are generally used.

But, these methods are expensive and they also requires

expertise and quite time-consuming sample preparation

processes. It was found that to be possible the detection

of hybridization with label-free methods which are

based on a guanine signal.

2. Experimental

Oxidation signal of most electroactive and stable DNA’s

base, guanine, approximately at about +1.0V is used in

this study. It is the first time that pencil graphite

electrode (PGE) surface is coated with silica gel which

is containing metal nanoparticles. PGE modification

was performed by immersing the PGE in ultrapure

water containing different concentration of silica gel

with different concentration of silver, zinc and cobalt

nitrate salts. After the PGE surfaces coated with silica,

PGEs were placed outside to dry. Probe was

immobilized onto the modified PGE containing probe.

After immobilization, probe-modified PGEs were rinsed for the removing of the unbound DNA at the electrode

surface. Probe modified PGE were immersed into the

target solutions and waited at the room temperature for

immobilization. After hybridization, non-specific

adsorption effects were minimized with the following

washing step. The treated and washed electrode was

transferred into ABS (pH 4.80) and the oxidation signal

of guanine was measured by using DPV in ABS by

scanning +0,75 to +1,25 V. Silica gel and metal ion

concentrations, selection of buffer solution for probe,

for hybridization and for measurement, probe and target concentrations, probe immobilization time,

hybridization time and washing time after the

hybridization were studied in order to find optimum

analytical performance of the developed sensor.


For the determining of optimum operation conditions, it

was based on that the oxidation signal of guanin signal

at the single-strand DNA (ssDNA) is more than the

signal at the double-strand DNA (dsDNA). The

conditions which give the best possible distinction

between the ssDNA, dsDNA were determined as the

optimum conditions of assay.

In Fig. 1, we compared the guanine signals obtained

from probe by using only silica gel, silver, cobalt, zinc nitrate salts and silica gel with silver, cobalt, zinc nitrate

salts. First of all, 20% silica gel, silver, cobalt, zinc

nitrate solutions and silica gel solution with 20% silver,

cobalt, zinc nitrates were prepared in ultrapure water.

The highest signal ratio was observed with solution of

silica gel and cobalt nitrate salts and this surface

modification was used for further experiments.

Figure 1. The guanine signals and percentage increase

guanine signals of probe coated surface under different

surface modifications.

Figure 2. Voltammograms of guanine signals

4. Conclusions

These results showed that the developed biosensor

selectively connect to the target and showed that it is

possible to determination of hybridization. Our method

is easy to apply, no need to expensive equipment, fast

response system, and no using of any toxic or

radioactive agents. For these reasons, it is powerful

alternative to classical methods.



Self-Powering Biosensors for Biofuel Cell Applications

Nilgün Dükar1*, Mehmet Yılmaz2, Gökhan Demirel2 and Filiz Kuralay1

1Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey

2Department of Chemistry, Faculty of Sciences, Gazi University, 06500 Ankara, Turkey


Abstract

Biofuel cell (BFC) is a type of fuel cell that uses

microorganisms to produce electricity, rather than

precious metals. They work on the same general

principles as all fuel cells: use a catalyst to separate

electrons from a parent molecule and force it to go

around an electrolyte barrier to generate an electric

current. There are 2 types of biofuel cells: Enzymatic

biofuel cells and microbial fuel cells.

An enzymatic biofuel cell is a specific type of fuel

cell that uses enzymes as a catalyst to oxidize its fuel, while a microbial fuel cell is a bio-electrochemical

system that drives a current by using bacteria and

mimicking bacterial interactions found in nature.

Enzymatic biofuel cells have attracted considerable

interest owing to their ability to provide sustainable

energy from renewable fuel sources under mild

conditions [1-5]. The ability to engineer these devices to

process various renewable biochemical species holds

considerable promise for the utilization of BFCs as

implantable power sources for biomedical devices.

In this study, we describe a self-powered enzyme- based

biosensors for biofuel cell applications (Figure 1). The

anode of the study consisted of a glucose oxidase (GOx)

entrapped peptide nanostructures (using diphenylalanine

peptides) modified screen printed gold electrode. The

enzyme immobilized nanostructured anode used glucose

as the fuel and Meldola’s Blue as the mediator. The

vertical aligned peptide nanostructures were fabricated

in a conventional physical vapor deposition system onto

the electrode.6 Then, GOx immobilization was

performed onto the electrode. Lactate dehyrogenase (LDH) entrapped poly(3,4-ethylenedioxythiophene)

coated gold electrode was used as the cathode material

of the study. 3,4-ethylenedioxythiophene monomer was

electropolymerized in the presence of LDH at a constant

potential of +0.8 V vs. Ag/AgCl onto the electrode.

Acknowledgments: F. Kuralay acknowledges Turkish

Academy of Sciences (TÜBA) as an associate member

and TÜBA-GEBİP programme.

Figure 1 Schematic representation of the work

References

[1] M. Zhou, N. Zhou, F. Kuralay, J.R. Windmiller, S.

Parkhomovsky, G. Valdes-Ramirez, E. Ktaz, J.

Wang, Angew. Chem. Int. Ed. 51 (2012) 2686.

[2] M. Zhou, F. Kuralay, J.R. Windmiller, J. Wang, Chemical Communications 48 (2012) 3815.

[3] E. Katz, A.F. Bückmann, I. Willner, J. Am. Chem.

Soc. 123 (2001) 10752.

[4] Y. Hu, Y. Zhang, C. Xu, L. Lin, R.L. Snyder, Z.L.

Wang, Nano Letters 11 (2011) 2572.

[5] M. Gamella, N. Guz, S. Mailloux, J.M. Pingarron,

E. Katz, Electroanalysis 26 (2014) 2552.

[6] G. Demirel, U. Tamer, Nanotechnology 23 (2012)

225604.



Electrochemical Biosensor for Penicillin G Detection

Nilgün Dükar1* and Filiz Kuralay1



Abstract

Antibiotics play an important role in biological systems. They are large and natural groups of pharmaceuticals

used in animals and humans for the treatment of

diseases. However, the use of antibiotics may lead to

drug residues and accumulation of antibiotics. The

accumulation of antibiotics in food-producing animals

has become a concern, because of their potential to

cause serious threats to public health. Penicillin G

belongs to the β-lactam group of antibiotics. The

presence of penicillin residues might be responsible for

allergenic reaction in human. Penicillin G residues may

also be responsible for the development of resistant strains of bacteria [1-3].

Electrochemical techniques used in biosensing

technology which are capable of high sensivity, good

stability, low-cost instrumentation and probability for-

on site monitoring have received tremendous attention.

Recently, most common materials used in biosensor

technology are nanaomaterials such as nanoparticles,

carbon nanotubes and graphene. Among these

nanomaterials, carbon nanotubes are of great interest.

Carbon nanotubes have captured the interest of

researches world-wide due to their small size with large surface area, high electrical conductivity, chemical

stability, and mechanical strength. [4].

In this study, we present a multiwalled carbon nanotubes

(MWCNTs) modified disposable screen printed gold

electrode for the detection of Penicillin G. In the first

part of the study, MWCNTs, prepared at different

concentrations, were modified on the disposable gold

electrode surface. The electrochemical behavior of the

electrodes were investigated in 0.1 M KCl solution

containing 5 mM Fe(CN)6 3-/4-

redox probe (Figure 1). Penicillinase enzyme was then immobilized and

amperometric detection of Penicillin G was performed.

Cyclic voltammetric behaviors of the modified

electrodes were also examined. The biosensor

monitored the catalytic hydrolysis of Penicillin G in a

very sensible manner.




Figure 1. Cyclic voltammograms of (a) 2.5 mg mL-1

MWCNTs modified electrode, (b) 2.0 mg mL-1 MWCNTs

modified electrode, (c) unmodified electrode, (d) 1.0 mg

mL-1 MWCNTs modified electrode in 0.1 M KCl

containing 5 mM Fe(CN)6 3-/4-.

References [1] P. Thavarungkul, S. Dawan, P. Kanatharana, P.

Asawatreratanaku, Biosensors and Bioelectronics 23

(2007) 688.

[2] Z. Yan, N. Gan, T. Li, Y. Cao, Y. Chen, Biosensors

and Bioelectronics 78 (2016) 51.

[3] L.M. Gonçalves, W.F.A. Callera, M.D.P.T.

Sotomayor, P.R. Bueno, Electrochemistry

Communications 38 (2014) 131.

[4] F. Kuralay, M. Dumangöz, S. Tunç, Talanta 144

(2015) 1133.



Gold Nanoparticle-based Colorimetric Assay for Chiral Discrimination of

D-/L-Alanine Enantiomers

Nisa Bekar1*

and Erhan Zor2

1 Department of Chemistry Education, Necmettin Erbakan University, Konya, Turkey

2 Department of Science Education, Necmettin Erbakan University, Konya, Turkey


4. Introduction

The development of a simple and efficient method for

enantioselective chiral discrimination is tremendously

valuable for drug discovery, pharmaceuticals and

biochemical processes [1]. In recent years, great success

has been attained in chiral discrimination by high-

performance liquid chromatography, gas

chromatography and electrochemical techniques. Apart from the conventional application of these techniques,

one of the most pressing challenges in chiral

discrimination is to achieve rapid and simple visual

discrimination of enantiomers by naked-eye.

Considerable effort has been devoted to the synthesis

and characterization of chiral selective metal

nanoparticles. However, the field of colorimetric chiral

discrimination using metal nanoparticles still remains

unexplored. In recent decades, the use of gold

nanoparticles (AuNPs) as optical label leads to a wide

range of applications in (bio)sensors due to their characteristics such as ease of synthesis and their

intense red color easy to be detected even by naked eye

[2]. Taking advantage of AuNPs, we herein report a

colorimetric assay for chiral discrimination of D/L-

alanine enantiomers. The mechanism is based on the

inherent chirality of citrate-capped gold nanoparticles

that can be used as chiral selector for D- and L-alanine.

2. Experimental

AuNPs were synthesized according to Turkevich

method [3]. Briefly, a sodium citrate solution (1%, 1.25

mL) was rapidly added to a boiled HAuCl4 solution

under vigorous stirring. The mixed solution was boiled

for 10 min while observing the color change from deep

blue to wine-red. The resulting solution was cooled to

room temperature and stored in the refrigerator (4 ˚C).


Figure 1 shows TEM image of the as-synthesized

spherical AuNPs with the average size 8 nm. Aiming at

examining the chiral recognition ability of the AuNPs D-/L-alanine were added into the AuNPs solution, then

visual and spectroscopic detection was performed.

Figure 2 shows UV-Vis spectra of as-synthesized

AuNPs, D-alanine/AuNPs and L-alanine/AuNPs

solutions. An absorption maximum was observed at 518

nm originating from the surface plasmon absorption of

the dispersed AuNPs. The absorption maximum was

red-shifted in the presence of L-alanine whereas no

change was monitored in the presence of D-alanine.

These results indicate L-alanine could selectively induce

aggregation of AuNPs, but D-alanine shows no effect.

Figure 1 TEM image of the as-synthesized AuNPs

The inset in Figure 2 displays the colorimetric assay of

chiral discrimination in which a well-marked red-to-

blue color change was observed in the presence of L-

alanine, whereas no color change could be observed in

the presence of D-alanine.

Figure 2 Absorption spectra of AuNPs in the presence

of D-alanine, L-alanine. The inset shows the

colorimetric assay photographs

Taking advantage of the inherent chirality of AuNPs,

it can be concluded that the proposed simple sensor can

be used as a convenient colorimetric probe to

discriminate alanine enantiomers, which can be a

promising model for discrimination of other biologically

important enantiomers of chiral molecules.

4. References

[1] Wattanakit et al., Nature Commun., 2014, 3325, 1-8.

[2] Quesada-Gonzalez and Merkoçi, Biosens. Bioelectron., 2015, 73,

47-63.

[3] Turkevich et al., Discuss. Faraday. Soc. 1951, 11, 55–75.



Double-Arm Schiff Bases-Tagged Nanomaterial; Synthesis and

Acetylcholinesterase Immobilization

N. Kurnaz Yetim1,2*, E. Hasanoğlu Özkan1, E. Karmaz1 and N. Sari1

1 Department of Chemistry, Gazi University, Ankara, Turkey 1 Department of Chemistry, Kırklareli University, Kırklareli, Turkey


Introduction

Recently there has been a considerable interest in the

material chemistry of nanoparticules involving metal

ion because of their potential medicine and industrial

applications [1]. The use of nanoparticules in medicine

and more specifically drug delivery is set to spread

rapidly. Nanoparticules involving metal ion play a very

important role not only in chemical reactions

(enzymatic reactions) in the human body but also in

industrial chemical processes [2]. AChE biosensors have been used to detect unknown toxic mixtures, but

there are some problems with the identification of toxic

mixtures in samples. Therefore, new methods are being

investigated by authors. One of these methods is the

immobilization of enzymes onto nanospheres. There has

been an increase in studies on enzyme immobilization

on nanospheres due to their small size and large surface

area.4,5 Nanospheres are useful for improving the

operational stability of immobilization. Therefore

enzyme immobilization into or onto various

nanoparticles has been proposed and reported.

Experimental

To prepared such a support, the N-{2-[Bis(2-

aminoethyl)amino]ethyl}aminomethyl-polystyrene

(2AEPS) reacted with 2-bromo salicylaldehyde by

means of condensation method.

4.1. Immobilization of AChE on nanomaterial

(2AEPS-SalBr)

After dissolving enzyme in pure water (50 mL, 3.6 x 10-

4 gL-1), 2AEPS-SalBr polymer (0.5 g) was placed to a 2

mL of 3.6 x 10-4 gL-1 of AChE. This solution was diluted to 10 ml and at room temperature in a shaking

water bath for 8 h. The immobilized polymer was

separated and the free enzyme was removed by washing

with phosphate buffer and then stored at + 4 °C.

Conclusion

The apparent kinetic parameters of the immobilized

enzyme and free enzyme were compared, and this

showed that the Michaelis constant (Km) of the

immobilized AChE was higher than that of the free

AChE, while there was a significant difference in the

maximum reaction rates (Vmax).

Figure 1 Mechanism for the catalytic activity of AChE

Kinetic parameters were studied for free AChE and

immobilized AChE optimum at pH=8.0 and optimum

temperature (50 oC). Km/Vmax values were calculated

from Lineweaver-Burk plots for immobilized AChE to

the novel support, 1.443 mM and 0.251 mMmin-1

respectively for 50 °C. patterns because they may not be

reproduced properly.

Table 1Kinetic parameters (Km/Vmax; mM/mM min−1)

for free AChE and immobilized AChE

pH Temp.

(°C)

Km/Vmax

(mM/ mM

min−1

)

Free Enzyme 8

50 0.146/1.85

AChE-2AEPS-

SalBr

8 50 1.443/0.251

References

[1] M.C.Daniel, D. Astruc, J. Chem. Rev. 104 (2004) 293.

[2] W.H. De Jong, P.J.A. Borm, Int. J. Nanomed. 3 (2) (2008) 133.

[3] E. Hasanoğlu Özkan, N. Kurnaz Yetim, D. Nartop and N. Sarı, J. Indian Eng. Chem., 25 (2015), 180.

[4] N. Özdem, E. Hasanoğlu Özkan, N. Sarı, F. Arslan and H. Tümtürk, Macromol. Res. 22(12) (2014) 1282.



A Sensitive Electrochemical Biosensor for Determination of Gallic Acid Based on

Polyimide Modified Electrode

Aziz Paşahan1, Nurcan Ayhan1*, İmren Özcan, Serap Titretir Duran1, Süleyman Köytepe1

İnönü University, Faculty of Arts and Science, Chemistry Department, 44280, Malatya, Turkey

*Presenter: nurcan1658hotmail.com

Abstract

Gallic acid (GA), a type of phenolic acid, is occurring in

plants in the form of free acids, esters, and catechin

derivatives[1]. It is commonly used in the

pharmaceutical industry and food industry[2]. Gallic

acid is used as a standard for determining

the phenol content of various analytes. In recent years,

many methods such as chemiluminescence

spectrophotometry and capillary electrophoresis as

well as chromatography were introduced to determinate

of phenolic compounds[3-4]. Electrochemical methods

were used for determination of GA due to low detection

limit, very fast response time, high sensitivity and simplicity[5].

In the present study, a novel polyimide film as selective

membranes was synthesized from 1,5-

diaminonaphthalene and 3,3',4,4'-benzophenonetetra-

carboxylic dianhydride through polycondenzation

reaction and thermal imidization. The prepared

polyimide films were characterized for their structure, morphology, and thermal behavior by Fourier transform

infrared spectroscopy (FTIR), scanning electron

micrograph (SEM), X-ray diffraction (XRD) and

thermal analysis (DTA/TGA/DSC) techniques. The

polyimide membrane was exhibited the highest Tg

because of the rigid heterocyclic unit. The polyimide

were formed by casting the film on the surface of bare

platinum electrodes in one-step procedure. For the

preparation of PI electrode, firstly, a solution of polymer

was made by dissolving about 0,1 g of the obtained dark

amber powdery polyimides in 1 ml of NMP. Then, the

prepared polyimide solution (2 µL) was cast on the surface of bare platinum working electrodes and

polyimide film was dried at room temperature for at

least 2 days.

Differential Pulse Voltammetry (DPV) technique was

used to investigate the electrochemical behavior of the

GA and interference species at modified electrode.

Therefore, it is claimed that the polyimide film can be

used as selective matrix for the rapid and accurate

detection of gallic acid in the presence of various

interferant molecules.

Fig 1. DPV behaviours of 2 mM gallik acid, 2 mM

caffeic acid, 2 mM Ascorbic acid and 2 mM coumaric acid at polyimide modified electrode.

References

[1] M. Naczk, F. Shahidi, J. Pharm. Biomed. Anal. 41

(2006) 1523–1542

[2] S. M. Fiuza, C.Gomes, L.J. Teixeira, MT. Girao da

Cruz, M. N. D. S. Cordeiro, N Milhazes, F.Borges,

M.P.M. Marques, Bioorganic & Medicinal

Chemistry 12 (2004) 3581–3589.

[3] X. Shao, L.S Lv, T. Parks, H. Wu, C.T. Ho, S.M.

Sang, J. Agric. Food Chem. 58 (2010) 12608–

12614.

[4] R.L.C Chen, C.H. Lin, C.Y. Chung, T.J. Cheng, J.

Agric. Food Chem 53 (2005) 8443–8446.

[5] B.B. Petkovic, D. Stankovic M. Milcic, S.P. Sovilj,

D. Manojlovic 132 (2015) 513–519


https://en.wikipedia.org/wiki/Standard_solution

https://en.wikipedia.org/wiki/Phenol


Electrochemical and nonenzymatic glucose biosensor based on

MDPA/MWNT/PGE nanocomposite

Özge Sürücü1*, Gulcin Bolat1 and Serdar Abaci1

1 Department of Chemistry, Hacettepe University, 06800, Beytepe, Ankara, Turkey


1. Introduction

Multi-walled carbon nanotubes (MWNTs) are multiple

layers of graphite superimposed and form a tubular

shape rolling in on themselves. Organic dyes, especially

azo dyes can combine with MWNTs with strong π-π

interactions to form stable hybrids [1]. Electrocatalytic

activity of MWNTs and azo dyes combinations exhibit

excellent properties such as high mechanical stability

and sensitivity for different electrochemical techniques

possessing excellent responses to various substances

such as as redox proteins, drugs, small biomolecules,

hormones, and so on.

A number of studies have been carried out to monitor

blood glucose levels [2]. Among these studies,

electrochemical and optical methods have been

extensively developed to monitor glucose. The

electrochemical and nonenzymatic sensing of glucose is

a cost-effective and rapid approach. Recently, various

nanomaterials have been developed as excellent nanocatalysts to provide new surfaces for fabricating

novel nonenzymatic glucose sensors.

The nonenzymatic sensing of glucose has been widely

investigated in a variety of fields ranging from

biomedical applications to ecological approaches.

Among these fields, electrochemical methods contain

great advantages such as high electrocatalytic ability,

high sensitivity and good selectivity to the electrooxidation of glucose. In this study, the strong

noncovalent adsorption of novel synthesized (E)-4-((5-

methylthiazole-2-yl)diazenyl)-N-phenylaniline (MDPA)

on the surface of MWNT/PGE was performed

electrochemically, and the prepared stable, uniform and

sensitive film (MDPA/MWNT/PGE) was used for

nonenzymatic and direct determination of glucose. The

surface of modified electrodes was characterized using

scanning electron microscopy (SEM) and

electrochemical impedance spectroscopy (EIS)

techniques. The improvement of electrooxidation response of glucose was completed using MDPA/

MWNT/PGE nanocomposite. The effects of scan rate

and pH on the peak potential and peak current of

glucose signal were determined. The limit of detection

and linear range were calculated using various

concentrations of glucose. Interference studies were

performed using coexisting substances including metal

ions such as Al3+, Cu2+, Fe3+ and ascorbic acid to

determine the selectivity of MDPA/MWNT/PGE for

glucose.


Electrocatalytic performance of the modified surfaces

towards the oxidation of glucose was investigated by

SWV between -0.8 V and 0.0 V vs. Ag/AgCl in 0.1 M

NaOH solution containing 5.0 mM glucose. SWVs of

1.0 mg mL-1 MWNT and 1.0 mM MDPA co-deposited

PGE, 1.0 mM MDPA over 1.0 mg mL-1 MWNT

deposited PGE, 1.0 mg mL-1 MWNT over 1.0 mM

MDPA deposited PGE and bare PGE were represented

in Figure 1. Oxidation process of glucose started at -0.8

V following two oxidation peaks at -0.6 V and -0.4 V

vs. Ag/AgCl. The results indicated that the modification improved the electrocatalytic activity towards the

oxidation of glucose. The former peak was oxidation of

glucose to glucolactone and the other was originated

from consequent oxidation of glucolactone [3]. The

main differentation of MDPA over MWNT deposited

PGE (red line) was obtained at -0.6 V vs. Ag/AgCl

observing 5-folds higher current enhancements from

bare PGE (green line) and the proposed surface was

titled as MDPA/MWNT/PGE.

Figure 1. Square wave voltammograms of 1.0 mg mL-1

MWNT and 1.0 mM MDPA co-deposited PGE, 1.0 mM

MDPA over 1.0 mg mL-1 MWNT deposited PGE, 1.0

mg mL-1 MWNT over 1.0 mM MDPA deposited PGE

and bare PGE between -0.8 V and 0.0 V vs. Ag/AgCl in

0.1 M NaOH solution containing 5.0 mM glucose.

References

[1] C. Hu, S. Hu, Journal of Sensors, Volume 2009,

Article ID 187615, 40 pages.

[2] A. Caduff, M. S. Talary, P. Zakharov, Diabetes

Technol. Ther., 2010, 12, 1–9.

[3] L. Larew, D. Johnson, J. Electroanal. Chem., 1989,

262, 167–182.



pH/Redox-Sensitive Hybrid Nanocarriers for Triggered Delivery

R. Tekiner1,2* and G. Birlik Demirel1,2

1Department of Chemistry, Polatli Faculty of Arts and Sciences, Gazi University, Ankara, Turkey 2 Life Sciences Research and Application Center, Gazi University, Ankara, Turkey


Abstract

Cancer remains one of the world’s most devastating

diseases, with more than 10 million new cases

every year[1]. In traditional treatment methods, anti-

cancer drug molecules circulate freely in the blood and

do not exhibit targeted release and kill the healthy cells

besides cancer cells. Because of these reasons and

considering the emerging technology, the scientists

from many disciplines study intensively for the

development of new-generation nanocarrier systems [2,3]. Nanocarriers have many advantages compared to

traditional methods. First of all, the drug molecules are

trapped into the nanocarriers and the toxicity of drug

can be decreased in minimum levels. Thus uncontrolled

delivery can be prevent and the drug dose can be

adjusted to minimum but effective levels. In the light of

the existing information scientists have focused on the

multifunctional and routable nanocarrier systems which

can do selective and controlled release [4-6]. In this

study, we have developed a novel pH/redox-sensitive

hybrid nanocarrier system for controlled drug delivery as seen in Scheme 1.

Scheme 1. Schematic mechanism of the intracellular

pH/redox-controlled release of designed hybrid system

Multifunctional and ellipsoidal hybrid nanoparticles

(Fe3O4@SiO2@PLH-PEG/PEG-FA) composed of an

ellipsoidal Fe3O4 core, a mesoporous silica shell and pH/redox-responsive poly(histidine)-co-poly(ethylene

glycol) (PLH-co-PEG) polymer as gatekeeper and PEG-

Folic acid (PEG-FA) polymer as targeted agent to

obtain an excellent platform for anticancer drug

delivery. In particular, the PLH-co-PEG gatekeeper on

the surface of the hybrid nanoparticle play a key role in

accommodating anticancer drug molecules in the pore

of the silica shell without premature release until

crosslinked polymer shell gatekeepers are cleaved by glutathione (GSH). In addition to PEG-FA polymers

provide to enhance the targeted cellular uptake of the

particles by cancer cells. The experimental results

showed that smart nanoparticles exhibit fast dissociation

in the presence of 10 mM GSH, due to the reductive

cleavage of intermediate disulfide bonds of PLH-PEG

polymer. It can be said that this multifunctional polymer

shell is active for the controlling drug molecules in-and-

out of silica channels. Moreover, the ellipsoidal smart

nanoparticles allowed the perfect release profile under

cellular pH environment. As a result, this study which

involve the experimental and applied research, will help the development of new generation nanocarrier systems.

In our belief, the obtained each result from every step

will be very precious to reach excellent systems in this

field and will provide very big contribute to the

literature.

Acknowledgement: This work was supported by the

TUBITAK Grant No. 115R280.

References

[1] Stewart, B. W., Kleihues, P. 2003. “World cancer

report world health organization press”, Genova, 9-11.

[2] Drbohlavova, J., Chomoucka, J., Adam V.,

Ryvolova, M., Eckschlager, T., Hubalek, J., Kizek, R.

2013. “Nanocarriers for anticancer drugs - new trends in

nanomedicine”, Current Drug Metabolism, 14, 547-564.

[3] Duncan, R. 2006. “Polymer conjugates as anticancer nanomedicines”, Nat. Rev. Cancer, 6, 688–701

[4] Cho, K. J., Wang, X., Nie, S. M., Chen, Z., Shin, D.

M. 2008. “Therapeutic nanoparticles for drug delivery

in cancer”, Clin. Cancer Res., 14, 1310-1316.

[5] Mishra, B., Patel, B. B., Tiwari, S. 2010. “Colloidal

nanocarriers: a review on formulation technology, types

and applications toward targeted drug delivery”,

Nanomed.-Nanotechnol. Biol. Med., 6, 9-24.

[6] Peer, D., Karp, J. M., Hong, S., FaroKhzad, O. C.,

Margalit, R., Langer, R. 2007. “Nanocarriers as an

emerging platform for cancer therapy”, Nat. Nanotechnol., 2, 751-760.



Preparation of a Biosensor for Determination of Choline

R. Baskın1*, E. (Aynacı) Koyuncu1, H. Arslan2 and F. Arslan2

1Department of Chemistry, Institute of Sciences, Gazi University, Ankara, Turkey

2Department of Chemistry, Faculty of Science, Gazi University, Ankara, Turkey


1.Introduction

Choline is an amino alcohol and a component of

lecitines [1,2]. It has many important biochemical roles.

It is one of the fundamental components of cell

membranes, a major component of phospholipids

(phosphatidylcholine) [3]. Furthermore, choline is the

precursor molecule for significant neurotransmitter

acetylcholine in both peripheral and central nervous

system of mammals [4,5]. So, choline detection and

determination is very important for clinical analyses. In

this study, we report a new choline oxidase (ChO) and Toluidine Blue O (TBO) based amperometric choline

biosensor for the determination of choline.


In this study, an amperometric choline biosensor with

immobilization of TBO (as a mediator,), ChO onto

polypyrrole-polyvinylsulphonate (PPy-PVS) film was

accomplished on the surface of a platinum electrode.

ChO and TBO were immobilized by a

glutaraldehyde/bovine serum albumin crosslinking

procedure onto PPy-PVS film after the

electropolymerization process. The effects of substrate concentration, pH and temperature on the response of

the choline biosensor were investigated. The operational

and storage stability of the biosensor were also studied.

The amperometric response was based on the

electrocatalytic properties of TBO. The changes in the

anodic current at -0.23 V vs Ag/AgCl produced by TBO

was proportional to the choline concentration changes in

sample (Figure 1).


In this study, a novel amperometric choline biosensor

with ChO, and TBO onto PPy-PVS film was

accomplished. The optimum working conditions with

respect to the substrate concentrations were

investigated. The effects of pH and temperature were

investigated and optimum parameters were found to be

7.0 and 30.0 ˚C, respectively. The storage stability and

operational stability of the enzyme electrode were also

studied and linear range was determined. Interfering

effect of some common substances was investigated.

The experimental results clearly showed that the choline

biosensor was sensitive and selective and its operational

stability and long-term storage stability were found to

be good. This biosensor was also easy to prepare and

was highly cost effective.

Figure 1 Reaction scheme for the detection of choline

7. References

[1] Özdemir, M., Arslan, F. and Arslan, H. (2012). An

amperometric biosensor for choline determination

prepared from choline oxidase immobilized in

polypyrrole-polyvinylsulfonate film. Artificial Cells,

Blood Substitutes, and Biotechnology, 40, 280-284.

[2] Langer, J.J., Filipiak, M., Kęçińska J., Jasnowska, J.,

Włodarczak, J. and Buładowski, B. (2004). Polyaniline

biosensor for choline determination. Surface Science, 573, 140-145.

[3] Galban, J., Sanchez-Monreal, O., Andreu, Y., de

Marcos, S, and Castillo, J.R. (2004). Choline

determination based on the intrinsic and the extrinsic

(chemically modified) fluorescence of choline oxidase.

Analytical Biochemistry, 334, 207-215.

[4] Aynacı, E., Yaşar, A. and Arslan, F. (2014). An

amperometric biosensor for acetylcholine determination

prepared from acetylcholinesterase-choline oxidase

immobilized in polypyrrole-polyvinylsulpfonate film.

Sensors and Actuators B: Chemical, 202, 1028-1036. [5] Garguilo, M.G. and Micheal, A.C. (1995).

Optimization of amperometric microsensors for

monitoring choline in the extracellular fluid of brain

tissue, Analytica Chimica Acta, 307, 291-299.


https://en.wikipedia.org/wiki/Acetylcholine


Ascorbic acid, dopamine and uric acid determination using a novel, highly

selective and sensitive rGO/PPy-Pt sensor

Fatih Sen1, Sait Bozkurt1* and Ceyda Uluturk1


Turkey


Abstract

We report here an efficient and simple approach for the

preparation of a partially reduced graphene oxide

polypyrrole zinc oxide modified glassy carbon electrode

(RGO-Ppy-Pt/GCE). The modification of the RGO-

GCE consists of three steps. These include (i) chemical

synthesis of graphite oxide by a modified Hummer's method,1 (ii) exfoliation of graphite oxide to graphene

oxide (GO) by ultra-sonication and (iii) controlled

partial electrochemical reduction in 0.1 M phosphate

buffered medium (pH 3.0) via potentiodynamic cycling

(2 cycles) to obtain a partially reduced graphene oxide

modified glassy carbon electrodes (RGO-GCE). The

behaviour of the RGO-GCE towards ascorbic acid

(AA), dopamine (DA) and uric acid (UA) was

investigated by differential pulse voltammetry, with an

enrichment time of 3 minutes.2-3 Morphological (SEM

and TEM) and electrochemical characterization studies

were also reported. Finally, the performance of the RGO-GCE based sensor was successfully tested for

analysing UA and quantitative recoveries of AA and DA

in serum samples.

Figure: (a) DPV results of AA, DA and UA at GCE,

rGO/PPy-Pt modified electrodes

References

[1] O. Arrigoni and M. C. D. Tullio, Biochim. Biophys.

Acta, 2002, 1569, 1.

[2] J. H. Kim, J. M. Auerbach, J. A. R. Gomez, I.

Velasco, D. Gavin, N. Lumelsky, S. H. Lee, J. Nguyen,

R. S. Pernaute, K. Bankiewicz and R. McKay, Nature,

2002, 418, 50.

[3] V. S. E. Dutt and H. A. Mottola, Anal. Chem., 1974,

46, 1777.



-0,2 0,0 0,2 0,4 0,6 0,8

-120,0µ

-60,0µ

0,0

60,0µ

120,0µ

180,0µ

240,0µ

300,0µ

360,0µ

420,0µ

AAI/A

E/V

Forward scan

DA

UA

Increase in scan no.

Incorporating PPy with ZnO Nanorods on Rgo: A Potentiometric Strategy for

Selectivity and Detection of Dopamine, ascorbic and uric acid

Fatih Sen1, Sait Bozkurt

1* and Ceyda Uluturk

1

1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupinar University.


Abstract

In this study, the investigation regarding the fabrication

of a reduced graphene oxide-polypyrole-platin

(rGO/PPy-ZnO) was carried out. The reduced graphene

oxide modified glassy carbon electrodes (rGO/PPy-

ZnO) were obtained by following procedure; graphite

oxide production, graphene oxide synthesis and finally, rGO/PPy-ZnO fabrication; chemical synthesis, ultra-

sonication and electrochemical reduction via

potentiodynamic cycling were used, respectively. The

differential pulse voltammetry (DPV) was utilized to

check rGO/PPy-ZnO performance against ascorbic acid

(AA), dopamine (DA) and uric acid (UA). At pH 3.0,

as-prepared electrode exhibits high sensitivity and give

precise and separate data for AA, DA and UA, they can

be examined separately and instantly. With 1x10-6 to

1,5x10-5 M detection limit, the series of the amounts of

2x10-1 M AA, 2x10-1 M DA and 1x10-1 to 2x10-1 M UA

were determined as the sensing intervals for as-prepared electrode. The as-obtained electrode was characterized

by morphologically and electrochemically. At the end,

for the analytical determination of UA and for

discovering the amount of AA and DA in serum

specimen, the rGO/PPy-ZnO was used [1-3].

Figure: (a) CV results of AA, DA and UA (each 1 x 10-3

M, scan rate 50 mV s-1) at GCE, rGO/PPy-ZnO

modified electrodes.

References

[1] O. Arrigoni and M. C. D. Tullio, Biochim. Biophys.

Acta, 2002, 1569, 1.

[2] J. H. Kim, J. M. Auerbach, J. A. R. Gomez, I. Velasco, D. Gavin, N. Lumelsky, S. H. Lee, J. Nguyen,

R. S. Pernaute, K. Bankiewicz and R. McKay, Nature,

2002, 418, 50.

[3] V. S. E. Dutt and H. A. Mottola, Anal. Chem., 1974,

46, 1777.



Nanomaterials-based DNA Damage Detection

Selma Tunc1* and Filiz Kuralay1



Abstract

Deoxyribonucleic acid (DNA) is the largest, well-

defined and also the most important molecule of life.

DNA plays an important role in the life process since it

carries heritage information and instructs the biological

synthesis of proteins and enzymes through the process

of replication and transcription of genetic information in

living cells [1-3].

Damage to DNA may result in critical disturbances in

the cell life. As a result of the damage, serious impacts

on human’s health can occur. DNA damage can lead to diseases such as Alzheimer, Parkinson’s disease and

cancer [4,5]. Thus, there is a considerable interest in the

development of highly sensitive and accurate sensing

platforms for the detection of DNA damage. Different

detection techniques have been employed responding to

DNA damage, including fluorescence, surface plasmon

resonance, quartz crystal microbalance and

electrochemistry.

Electrochemical techniques are well suited for rapid and

direct detection of DNA damage since DNA bases are electroactive. Furthermore, electrochemistry have

attracted great attention for the construction of sensitive,

selective, low-cost, rapid and simple sensing platforms.

Electrochemical biosensors can be operated in turbid

media, have comparable instrumental sensitivity and are

more amenable to miniaturization [6,7].

In this study, we present a graphene modified disposable

pencil graphite electrode (GN/PGE) for the detection of

DNA damage. DNA damage was investigated in the

presence and absence of Fenton reagents (Fe2+/H2O2) according to the changes in the oxidation signals of

DNA bases (Guanine, Adenine, Thymine, Cytosine). In

the first part of the study, we synthesized graphene

according to the modified Hummers’s method and

modified the synthesized graphene onto the graphite

electrode surface [8]. Unmodifed PGE and GN/PGE

were characterized by scanning electron microscopy

(SEM) (Figure 1) and cyclic voltammetry (CV). Then,

DNA damage was performed using Fenton reagents.

Electrochemical detection of the damage was carried

out with differential pulse voltammetry (DPV).

Improved electrochemical responses were obtained with the nanomaterials-based electrode compared to the

unmodified (bare) electrode. Well-defined oxidation

signals of DNA bases were observed using graphene

modified disposable graphite electrode, which later on

provided a better sensing platform for monitoring the

changes in the oxidation signals of DNA bases after the

damage.

Figure 1 SEM images of (a) unmodified PGE, (b)

GN/PGE

Acknowledgments: This work has been supported by L’Oréal-UNESCO For Women in Science Programme.

F. Kuralay acknowledges Turkish Academy of Sciences

(TÜBA) as an associate member and TÜBA-GEBİP

programme.

References [1] E. Palecek, Talanta 56 (2002) 809.

[2] F. Kuralay, S. Campuzano, J. Wang, Talanta 99

(2012) 155.

[3] F. Kuralay, A. Erdem, S. Abacı, H. Özyörük, A. [1]

Yıldız, Electrochem. Commun. 11 (6) 1242.

[4] M. Fojta, Electroanalysis 14 (2002) 1449. [5] E. Palecek, M. Fojta, Anal. Chem. 73 (2001) 74A.

[6] V. Ostatna, F. Kuralay, L. Trnkova, E. Paleček,

Electroanalysis 20 (13) 1406.

[7] F. Kuralay, A. Erdem, Analyst 140 (8) 2876.

[8] M. Zhou, Y. Zhai, S. Dong, Anal. Chem. 81 (2009)

5603.



Electrochemical Investigation of the Effect of Antioxidants on DNA

Damage

Selma Tunc1* and Filiz Kuralay1



Abstract Antioxidants are molecules that inhibit the oxidation of

other molecules. Chemical reactions-based on oxidation

can produce free radicals, leading to chain reactions that

may damage cells. It is well-known that antioxidants

such as glutathione, catalase, melatonin, uric acid,

Vitamin A, Vitamin C (ascorbic acid) (Figure 1) and

Vitamin E terminate these chain reactions [1,2].

The reactive oxygen species produced in cells include

hydrogen peroxide (H2O2) and free radicals such as the

hydroxyl radical (·OH) and the superoxide anion (O2−).

The hydroxyl radical is particularly unstable and reacts

rapidly and non-specifically with most biological

molecules. This species is produced from hydrogen

peroxide in metal-catalyzed redox reactions such as

the Fenton reaction. These oxidants can damage cells by

starting chemical chain reactions such as by oxidizing

DNA [3-5]. This damage to DNA can

cause mutations and possibly cancer, if not reversed

by DNA repair mechanisms. Researches have been

presented that antioxidant molecules can inhibit this

DNA damage [6].

In the present work, we investigate the effect of ascorbic

acid, glutathione and uric acid on the DNA damage

produced by Fenton reagents (Fe2+/H2O2). A graphene

modified disposable pencil graphite electrode

(GN/PGE) was used for the construction of the

biosensing platform for the investigation of the effect of

antioxidants on DNA damage. Graphene is a two-

dimensional (2D) carbon-based nanomaterial (sp2

hybridized carbon) which has unique properties such as

good thermal, electrical, optical and mechanical

properties, having high specific surface area and ultrahigh carrier mobility [7]. The invention of graphene

has been one of the milestones in nanotechnology. It has

been a great potential for various researches such as

electrochromic devices, lithium batteries,

supercapacitors, solar cells and (bio)sensing devices.

Thus, in the current study, graphene provided a

convenient interface on the graphite electrode by

enhancing the electrochemical properties of the sensing

surface, including good electrical conductivity, high

electroactive surface area and high mobility transport

performance.

Electrochemical detection of the effect of antioxidants

was carried out with differential pulse voltammetry

(DPV) using different concentrations of ascorbic acid,

glutathione and uric acid. The effect of different

interaction times were also examined in the study. It was

found that these molecules had the ability to inhibit the DNA damage.

Figure 1 Chemical structure of Vitamin C (ascorbic

acid)

Acknowledgements: This work has been supported by

L’Oréal-UNESCO For Women in Science Programme.

F. Kuralay acknowledges Turkish Academy of Sciences

(TÜBA) as an associate member and TÜBA-GEBİP

programme.

References [1] J. Labuda, M. Buckova, L. Heilerova, S. Silhar, I.

Stepanek, Anal. Bioanal. Chem. 376 (2003) 168.

[2] O. Korbut, M. Buckova, J. Labuda, P. Grundler,

Sensors 3 (2003) 1.

[3] A. Sancar, Chem. Rev. 103 (2003) 2203.

[4] K. Cahova-Kuchaříkova , M. Fojta ,T. Mozga, E. [1]

Palecek, Anal. Chem. 77 (2005) 2920.

[5] M. Fojta, Electroanalysis 14 (2002) 1449.

[6] Y. Yang, J. Zhou, H. Zhang, P Gai, X. Zhang, J.

Chen, Talanta 106 (2013) 206. [7] J. Wang, Analyst 130 (2005) 421.


https://en.wikipedia.org/wiki/Superoxide

https://en.wikipedia.org/wiki/Catalysis

https://en.wikipedia.org/wiki/Fenton_reaction

https://en.wikipedia.org/wiki/Mutation

https://en.wikipedia.org/wiki/DNA_repair

http://pubs.acs.org/author/Cahov%C3%A1-Kucha%C5%99%C3%ADkov%C3%A1%2C+Kate%C5%99ina

http://pubs.acs.org/author/Fojta%2C+Miroslav

http://pubs.acs.org/author/Mozga%2C+Tom%C3%A1%C5%A1


Plasma Enhanced Preparation of Graphene/Polyfuran Nanocomposites

Gamze Celik Cogal1,2, Sadik Cogal2, Filiz Kuralay3, Selma Tunc3*, Maria Omastova4, Matej Micusik4, Lutfi Oksuz5 and

Aysegul Uygun Oksuz1

1Department of Chemistry, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey

2Department of Polymer Engineering, Mehmet Akif Ersoy University, 15030 Burdur, Turkey 3Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey

4Polymer Institute, Dúbravska cesta 9, 845 41 Bratislava, Slovakia 5Department of Physics, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey


Abstract

Graphene is a 2D structure of carbon, which composed

of sp2-bonded single-layer carbon atoms with

honeycomb lattice. In the recent years, graphene has

received increasing attention due to its unique electrical,

optical, mechanical and termal and chemical stability

properties [1].

(a) (b)

Figure 1 Molecular structure of graphene (a) and

polyfuran (b)

Conducting polymers (CP) have also attracted

significant importance in different areas due to their ability to prepare polymer materials with similar

electrical and optical properties to semiconductors or

even metals. Among CPs, polyfuran is interesting

because of its possible technological applications such

as sensors and optoelectronic devices [2]. However, it

has been less studied due to difficulty of synthesis.

Although CPs exhibit excellent properties, some

properties such as electrical conductivity are not

sufficient for some applications and need to be

developed. One approach is combining the CPs with

graphene. The combination of the excellent properties of GR and conducting polymers in composite structures

enhanced the electrical conduction and electrocatalytic

activity of CPs.

In this study, graphene/polyfuran nanocomposites and

polyfuran homopolymers were synthesized using RF-

rotating plasma (Fig. 2) [3], which is fast, versatile and

environmentally friendly process. During the

experiment the plasma chamber was rotated under

constant rate for obtaining uniform coating of polyfuran

on the surface of graphene. The collected graphene coated with polyfuran was directly characterized

without further treatment.

Figure 2 RF-rotating plasma system used for

preparation of composites

The prepared materials were characterized by using

fourier transform-infrared spectroscopy (FT-IR),

scanning electron microscopy (SEM), thermal

gravimetric analysis (TGA) and electrochemical measurement.

Acknowledgements: This work has been supported by

TUBITAK-114M877 project.

References [1] Z. Yin, J. Zhu, Q. He, X. Cao, C. Tan, H. Chen, Q.

Yan, H. Zhang, Graphene-based materials for solar cell

applications, Adv. Energy Mater., 4 (2014) 1300574.

[2] M. Ates, A review study of (bio)sensor systems

based on conducting polymers, Materials Science and Engineering C, 33 (2013) 1853.

[3] A. Uygun, L. Oksuz, A.G. Yavuz, A. Guleç, S. Sen,

Curr. Appl. Phys., 11 (2011) 250.



Electrochemical Behavior of Cefuroxime Axetil

on Graphene Oxide Modified Glassy Carbon Electrode

S.Erdoğan Kablan1* and N. Özaltın1

1Department of Analytical Chemisty, Hacettepe University, Faculty of Pharmacy


Abstract The electrochemical oxidation behavior of Cefuroxime Axetil

(CEFA) on graphene oxide modified GCE was investigated by voltammetric methods in pH 2 Britton-Robinson buffer. A well-defined peak was observed at 1.30 V vs. Ag/AgCl for electrooxidation of CEFA at modified glassy carbon electrode (M-GCE) by using square wave voltammetry (SWV). Current type, reversibility of electrode reaction and the number of electrons transfered were investigated by using cyclic voltammetry (CV), chronoamperometry (CA) and chronocoulometry (CC). Besides the calculation of diffusion

coefficient and rate constant of electron transfer, the oxidation mechanism was also proposed.

1.Introduction

Cephalosporins are derived from Cephalosporium which is species of mushroom. They are antibiotics with a broad spectrum of antimicrobial and antibacterial properties and classified into four generations. CEFA is a second-generation cephalosporin and an oral prodrug formulation of the

injectable antibiotic cefuroxime (CEF). Chemical structure of CEFA is shown in Fig. 1. CEFA is the 1-acetoxyethyl ester of CEF. This ester product increases the lipophilicity and the oral bioavailability of the parent compound [1].

Figure 1. Chemical Structure of CEFA

There has not been a method described for the electrochemical

behaviors of CEFA using bare glassy carbon electrode (GCE) and graphene oxide modified glassy carbon electrode (M-GCE). Therefore, the aim of this work was to investigate the electrochemical behaviors of CEFA at M-GCE, and to propose the oxidation mechanism, by using SWV, CV, CA, and CC methods. Graphene/graphene oxide has gained technological importance in several years [2]. The oxidation peak current of

CEFA on bare GCE was too low for investigation (Fig.2). Thats why it has been decided to modify the GCE electrode with graphene oxide to increase the peak current. In this study the peak current (Ip) enhanced for 7-fold, compared to that bared GCE, in the presence of graphene oxide due to the increased surface area and improved electrical conductivity that occured by using graphene oxide modified GCE (Fig.2).

Figure 2. The Effect of Graphene Oxide Amount on Peak Current of 38.0 mg L-1 CEFA in Modification Process

There is no cathodic peak on the cyclic voltammogram of CEFA and the peak potential shifted to positive values with increasing scan rate, so CEFA oxidation is irreversible on M-GCE (Fig. 3). The Slope of (log Ip) vs (log v) graph was obtained 0.1396, which is lower than 0.50 indicates that oxidation current of CEFA was diffusion controlled. Because of the thin film on modified electrodes, the slope of (log Ip) vs (log v) decreases from 0.5 to lower values [3].

Figure 3. Cyclic Voltammograms of 16.13 µg mL-1 CEFA at different scan rates a) Supporting Electrolyte b)25 c)50 d)75 e)100 f)250 g)500 mV s-1

References

[1] A. Finn, A. Straughn, M. Meyer, J. Chubb, Effect of dose and food on the bioavailability of cefuroxime axetil, Biopharmaceutics & drug disposition 8 (1987) 519-526. [2] M. Pumera, Electrochemistry of graphene: new horizons for sensing and energy storage, The Chemical Record 9 (2009) 211-223. [3] M. Vilas-Boas, C. Freire, B. De Castro, A. Hillman, Electrochemical Characterization of a Novel Salen-Type

Modified Electrode, The Journal of Physical Chemistry B 102 (1998) 8533-8540.



Electrochemical Studies on the Anti-Parkinson Drug Pramipexole:Square Wave

Voltammetric Determination on Graphene Oxide Modified Pencil Graphite

Electrode and Investigation of Drug-DNA Interaction

Sevilay Erdoğan Kablan1* and Ceren Yardımcı1

1Department of Analytical Chemistry, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey


1. Introduction

Pramipexole is an orally active non-ergoline dopamine

agonist with selective activity at dopamine receptors

belonging to the D2 receptor subfamily (D2, D3, D4

receptor subtypes) and with preferential affinity for the

D3 receptor subtype. It is approved as monotherapy in

early Parkinson’s disease and as adjunctive therapy to

levodopa in patients with advanced disease experiencing

motor effects because of diminished response to

levodopa [1].

The widespread use of pramipexole and the need for

clinical and pharmacological study require fast and

sensitive analytical techniques to assay the presence of

the drug in pharmaceutical dosage forms and also in

biological samples. Electroanalytical methods have

proved to be useful for development of very sensitive

and selective methods for the determination of organic

molecules, including drugs and related molecules in

dosage forms and biological fluids.

The interaction of DNA with drugs is an important issue

in life sciences. The investigation based on DNA

interactions has great importance in understanding the

mechanism of action of many drug compounds,

designing of new DNA-drug biosensors and screening

of the drugs in vitro. Electrochemical DNA biosensors

enable the study of the interaction of DNA immobilized

on the electrode surface with analytes in solution.

In this study, the voltammetric behavior of pramipexole

at a graphene oxide modified pencil graphite electrode

and at a DNA biosensor is presented.

2. Method

The electrochemical behavior of pramipexole was

studied over a wide pH range (3.0–10.0) at graphene

oxide modified pencil graphite electrode using cyclic

and square wave voltammetry. The best definition of the

analytical signals was found in Britton Robinson buffer

(pH 4.0) at 0.8 V (versus Ag/ AgCl).

The peak current obtained in square wave voltammetry

is dependent on various instrumental parameters. The

optimized parameters can be summarized as follows:

frequency 40 Hz, amplitude 5 mV and pulse size 50

mV.

For investigating the interaction between DNA and pramipexole, differential pulse voltammetry and

guanine oxidation signal monitoring before and after

interaction between drug and DNA is used. The DNA

was immobilized on a pretreated pencil graphite

electrode by applying a potential at +0.5 V in 0.5 M

acetate buffer solution containing 0.02 M NaCl. The DNA modified pencil graphite electrode was immersed

in the blank 0.5 M acetate buffer (pH 4.8) containing

0.02 M NaCl and the oxidation signals of guanine were

recorded using differential pulse voltammetry. The

procedure was repeated using a new pencil graphite

electrode, the electrochemical response of pramipexole

was investigated using bare and DNA attached pencil

graphite electrode.


In this work, we combined the advantages of disposable

pencil graphite electrode and unique physicochemical

properties of graphene oxide. The relationship between

oxidation peak current and concentration of

pramipexole was linear. Validation parameters such as

sensitivity, accuracy, precision, and recovery were evaluated. The proposed method was employed for

quantification of pramipexole in different

pharmaceutical formulations. In addition, the DNA

modified pencil graphite electrode was used in

combination with differential pulse voltammetry to

obtain the information about the interaction between

DNA and pramipexole.

References

[1] M. Dooley, A. Markham, Drugs & Aging, 12 (1998)

495-514.



Catechol determination using a novel electrochemical nanobiosensor

S.Kurbanoglu1, 2*, Lourdes Rivas2, Sibel A. Ozkan1 and Arben Merkoçi2, 3

1Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, Ankara, TURKEY 2Nanobioelectronics & Biosensors Group, ICN2- Institut Catala de Nanociencia i Nanotecnologia, Campus

UAB, 08193 Bellaterra, Barcelona, Spain, 3ICREA, Barcelona, Catalonia, Spain


1. Introduction

Biosensors have great potential for achieving detect-to-

protect devices: devices that can be used in detections of

pollutants and other threating compounds/analytes

protecting citizens’ life [1].

Enzymes have high affinities toward corresponding

substrates being able to catalyze several biochemical

reactions without being permanently changed. The

recognition system of a biosensor directly depends on

the enzyme-substrate relation, which is measured by the transducer onto which surface enzymes are immobilized

[2].

Use of nanomaterials offers to biosensing platforms

exceptional optical, electronic and magnetic properties.

Nanomaterials can increase the surface of the

transducing area of the sensors that in turn increases

catalytic behaviors [3].

2. Experimental

Tyrosinase (Tyr) from mushroom (Z1000 unit/mg),

catechol was purchased from Sigma-Aldrich (St. Louis,

MO). As the electrochemical detector, screen printed carbon electrodes (SPEs) consisted of a set of three

electrodes: carbon working electrode with a diameter of

3 mm, Ag/AgCl pseudo reference electrode (with a

potential of 10 mV with respect to a commercial

Ag/AgCl electrode) and carbon counter electrode with

an approximate thickness of 4 μm were used.

In this study, a novel biosensing platform, for the

determination of catechol was designed, using carbon

nanotubes (CNTs), polythionine (pThi), Iridium oxide

nanoparticles (IrOx NPs) and tyrosinase.

3. Results In order to immobilize Tyr, firstly carbon nanotubes are

dropped on the surface of the screen printed electrodes.

0.5 mM Thionine was polymerized on the surface of

SPE/CNT between -0.4 V and 0.4 V with 50 mV/s scan

rate for 20 cycles in 0.1 M phosphate buffer. 0.25 %, 5

µL glutaraldehyde, 5 µL IrOx NPs and Tyrosinase were

added to immobilize tyrosinase.

To optimize the amperometric catechol response

different number of scans (5-30 CVs), different amount

of IrOx NPs (1-7 µL) and Tyr (2-10 µL) were studied.

Scanning Electron Images were obtained to follow the

surface changes by carbon nanotubes polythionine, Iridium oxide nanoparticles and tyrosinase (Figure 1).

Chronoamperometric responses of SPE modified with

SPE/CNT/pThi/IrOx/Tyr for continuous additions of 0.2

µM catechol while applying a -200mV potential.

Figure 1. SEM images of the designed biosensor. Scale

bars of SEM images are 200 nm. The SEM images were

obtained using backscatter electrons (BE) mode (right

column) and secondary electron (SE) mode (left

column).

The analytical characterization of the

SPE/CNT/pThi/IrOx/Tyr evaluated by continuous

additions of catechol at different concentrations. A

linear response for catechol with r= 0.99 0.2 to 48 µM

was observed. Within 10 s after each addition of

catechol, sensitive bioelectrocatalytic response reaches

about 95% of the steady-state current. Limit of detection

(LOD) and limit of quantitation (LOQ) values of the

developed biosensor were calculated according to the

3s/m and 10s/m criteria, respectively, where ‘s’ is the

standard deviation of the peak currents of low concentration of the analyte and ‘m’ is the slope of the

related calibration graph. LOD and LOQ values are also

calculated as 0.08 and 0.2 µM catechol, respectively.

Relative standard deviation (RSD) values were lower

than 15% for between day repeatability and lower than

10% for within-day repeatability [4].

References

[1] Thévenot, D. R., Toth, K., Durst, R. A., Wilson, G. S. (2001). Electrochemical biosensors: recommended definitions and classification. Biosensors and Bioelectronics, 16(1), 121-131. [2] Datta, S., Christena, L. R., Rajaram, Y. R. S. (2013). Enzyme immobilization: an overview on techniques and

support materials. 3 Biotech,3(1), 1-9. [3] Marín, S., Merkoci, A., Nanomaterials Based Electrochemical Sensing Applications for Safety and Security Electroanalysis 2012, 24, No. 3, 459 – 469 [4] S.A. Ozkan, “Electroanalytical methods in pharmaceutical analysis and their validation”, HNB Pub., New York, 2011.



Protein Adsorption and Real Time Cell Analysis of SAM Modified Au Surfaces

S. Eren1*, D. Hür2, L. Uzun3, B. Garipcan1 and Filiz Kuralay4

1 Institute of Biomedical Engineering, Boğaziçi University,

2 Department of Chemistry, Anadolu University, 3Department of Physics, Chemistry, and Biology, Linköping University

4Department of Chemistry, Ordu University


1. Introduction

Cell-surface interaction is one of the important topics that attract attention of researches to investigate effect of surface properties on cell behavior. Surface properties, such as wettability, chemistry, topography and stiffness have effect on cell adhesion. However, it should be considered that protein adsorption is occurred before cell adhesion. Due to this reason, protein adsorption has a key role that affects cell adhesion indirectly [1-3]. In this study, according to these

knowledge, protein adsorption and cell studies were run via Quartz Crystal Microbalance (QCM) biosensor and real time cell analyzer (RCTA) to observe effect of surface modifications on protein adsorption and cell adhesion.


In this study, novel amino acid (histidine, leucine, serine, and tryptophan) conjugated SAMs were synthesized in our laboratory, which have special affinity to Au surfaces and attracted by chemisorption [4].

Substrates were modified in-situ in flow cell during QCM (SRS, CA, USA) frequency measurement. 10mM SAM

solutions were used for modifications. In addition, water contact angle and XPS analysis were done to prove modifications.

Protein adsorption experiments were run after surface modifications with human albumin, fibrinogen for human plasma, and immunoglobulin G via QCM system with different concentrations.

xCellgance (ACEA Bioscienses, Boston, USA, kindly supplied by ELIPS, Turkey) was used for real time cell analysis. Before cell analysis, the Au electrodes of the system were modified with SAMs immersing method, and then cell analysis experiment was conducted for 48 hours with osteoblast cells. During experiment, cell culture medium and the application of a low voltage create an electric field between the electrodes, which is called cell index [6].

3. Results and Discussions

Proteins have significant role in determining the biocompatibility and cell adhesion according to amount, interaction strength, and conformation [5]. Aim of protein adsorption investigation part was manipulation of the protein adsorption by surface modifications. The surface modifications were proved by QCM frequency measurement,

water contact angle measurement, and XPS analysis before protein adsorption investigations.

According to results of the protein adsorption study,

fibrinogen has shown the highest affinity to Leu-SAM. In addition, Leu-SAM has highest affinity for all proteins than the other SAMs.

The cell index results of RCTA showed that Ser-SAM

modified surfaces have higher viability for cells than Leu-SAM modified surface. Leu-SAM modified surfaces have shown less effect on cell viability as a result of comparison with control group.

Figure 1 Osteoblast cells and Ser-SAM, Leu-SAM modified surfaces interaction real time analysis ,incubated at 37°C, 5% CO2 for 48 hours

References

[1] T. Jacobs, R. Morent, N. de Geyter, P. Dubruel, C. Leys, “Plasma surface modification of biomedical polymers:Influence of cell-material interaction”, Plasma Chem Plasma Process, 32, 1039-1073, 2012 [2] E. Psarra, U. König, Y. Ueda, C. Bellmann, A. Janke, E. Bittrich, KJ. Eichorn, P. Uhlmann, “Nanostructured

Biointerfaces: Nano-architectonics of Thermoresponsive Polymer Brushes Impact Protein Adsorption and Cell Adhesion”, ACS Appl Mater Interfaces, 17, 12516-29, 2015 [3] S. Hong, “Quantitative Analysis of Cell-Surface Interactions and Cell Adhesion Process in Real-time”, Phd. Thesis, Drexel University, 2008 [4] C.K. Akkan, D. Hür, L. Uzun, B. Garipcan, “Amino Acid Conjugated Self Assembling Molecules for Enhancing Surface

Wettability of Fiber Laser Treated Titanium Surfaces”, Applied Surface Science, 366, [5] C. Fornaguera, G. Caldero, M. Mitjans M.P. Vinardell, C. Solans, C. Vauthier, ”Interactions of PLGA nanoparticles with blood components: protein adsorption, coagulation, activation of the complement system and hemolysis studies” Nanoscale, 7, 6045-58, 2015 [6] J.M. Serra, “xCELLigence system for real-time label-free

monitoring of growth and viability of cell lines from hematological malignancies”, Onco Targets Ther, 7,985-994, 2014



Preparation of Poly(thionine) Supported Palladium Nanoparticles For

Biosensing Applications

S. Kırlak* and M. Sönmez Çelebi

Department of Chemistry, Faculty of Science and Arts, University of Ordu, 52200, Ordu, Turkey


1. Introduction

Conducting polymers have been widely studied due to their

potential applicability in fields like catalysis, electronic devices and sensor and biosensors design. Their ability to enhance electron transfer along with good sensitivity and versatility has attracted much interest in the use of conducting polymer films, namely polypyrrole, polythiophene and polyaniline, as suitable matrices for biomolecules immobilisation. For this purpose, the presence of free functional groups, appropriate for the interaction with biomolecules, provide further advantage [1].

Thionine (TH) is a phenothiazine redox dye which can be easily dissolved in water and ethanol. The chemical structure

of TH is a small planar molecule with two –NH2 groups symmetrically distributed on each side. Both thionine monomer and the electrogenerated poly-thionine (PTH) have excellent electrocatalytic activity toward the redox of small molecular compounds. Thionine has been used in many sensor applications [2].

Metal nanoparticles are objects of great interest in modern chemistry and materials research possessing physical as well as chemical properties, which are distinct both from the bulk phase and from isolated atoms and molecules. Metal nanoparticles supported on functional materials have many

advantages over unsupported nanoparticles. In connection with metal nanoparticles as the catalytically active moieties, the use of functional polymers offers some features, namely:

it allows the generation of metal nanoparticles with a controlled size and size distribution;

it provides a mean to influence the chemical behavior of the metal nanoparticles through the direct interaction of the metal surface with the polymer-bound functional

groups. The aim of the current study is to prepare a H2O2 sensor based on palladium (Pd) nanoparticles supported on poly(thionine) (PTH). Cyclic voltammetry was used for polymerization of TH from aqueous solution. Pd nanoparticles were immobilized onto the polymer matrix by bulk electrolysis with coulometry from aqueous K2PdCl4 solution without supporting electrolyte.

2. Experimental

In electrochemical studies, a glassy carbon electrode (GCE) (r = 1.5 mm) was used as the working electrode. A saturated calomel electrode (SCE) was used as the reference electrode

and a Pt wire was used as the counter electrode. Bulk electrolysis with coulometry and cyclic voltammetry studies were carried out with CH Instruments System, Model 600E.


PTH was coated onto the GCE surface by cyclic voltammetric scans between -0.4 V and +0.1 V vs. SCE from aqueous solution of TH containing 100 mM phosphate buffer (PBS, pH = 7.0) (Figure 1). PTH coated GCE was then washed with

distilled water and placed in a blank solution containing 100

mM PBS at pH 7.0 in order to record the cyclic voltammogram (CV) of the polymer film (Figure 2).

Oxidation and reduction peaks of the polymer were observed at -0.198 V and -0.233 V respectively. When we compare Figures 1 and 2, it is clear that the peak potentials are different than that of the monomer stating the formation of PTH.

Figure 1 Polymerization profile of TH

Figure 2 CV of PTH coated GCE

After this step, Pd nanoparticles were incorporated into the polymer matrix by bulk electrolysis from 2 mM K2PdCl4 solution at -0.8 V. It was observed that the so-prepared Pd/PTH modified GCE showed excellent catalytic activity towards reduction of H2O2 molecule which is involved in several biological events and is the by-product of many enzymatic reactions. So it is concluded that PTH supported Pd nanoparticles can be used to prepare an amperometric H2O2

biosensor.

References

[1] V. Ferreira, A. Tenreiro, L.M. Abrantes, Sensors and Actuators B, 119, 632 (2006). [2] A.W. Shi, F.L. Qu, M.H. Yang, G.L. Shen, R.Q. Yu, Sensors and Actuators B, 129, 779 (2008).



Electrochemical Impedimetric Immunosensor Based on Gold Nanoparticles

Functionalized Screen-Printed Gold Electrode for Carcinoembryogenic Antigen

(CEA) Tumor Marker Detection

Ş. Sultan1*, Ç. K. Rabia1 and K. Merve2

1 Department of Bioengineering, Yıldız Technical University, İstanbul, Turkey

2 Department of Medical Biology, S¿leyman Demirel University, Isparta, Turkey


Abstract

Impedimetric immunosensors are constructed with

antibody immobilization of working electrode and their

working principle is that occuring a correlation between

antigen concentration and obtained resistance after an

electrochemical Ab-Ag interaction. EIS is generally used to characterize these type detections in biosensor

applications [1]. Electrochemical impedimetric

biosensors have significant advantages for sensitive

detection of cancer biomarkers which are being smaller,

faster, more sensitive, cheaper devices, without

radiation hazards, allowing label-free, concurrent

detection, simple production, less time consuming, rapid

detection, having longer shelf life, and not complicated

procedure. These properties will substantially get easier

early dianostic of cancer at beginning phases.

Carcinoembryogenic antigens which are cell surface

glycoproteins [2] are used as an important biomarker in human serum associated with colorectal, lung, breast

cancer and ovarian carcinoma [3, 4]. CEA

quantification analysis with electrochemical impedance

spectroscopy promotes early diagnosis of cancer which

is crucial for the successful treatment of the disease and

increases health standards of people[5]. The gold layer

has various advantages during immobilization process

thereby the easy adsorption of biomaterials relates to

hydrophobic and thiol–gold interactions. In recent years,

gold nanoparticles (AuNPs) are commonly used to

enhance more sensitive electrochemical immunoassay for immobilization of antibody. AuNPs provide strongly

adsorbtion of antibody on working electrode during

immobilization due to its large specific surface area,

good biocompatibility, surface free energy of nanosized

particles [6, 7]. AuNPs facilitate electron transfer

between redox proteins and electrode surfaces, provide

effective mass transport in electrochemical biosensor

applications as making closer redox protein

(monoclonal CEA antibody) to the electrode via

nanosized structure. In the other words, AuNPs is a

desirable intermediator for immobilization of antibodies

[8]. In this study, the gold electrode is modified with thiol and AuNPs to develop an impedimetric biosensor

to detect CEA as an important cancer biomarker.

References

[1] M.I. Prodromidis, Impedimetric immunosensors-A

review, Electrochimica Acta, 55 (2010) 4227-4233.

[2] M. Taheri, U. Saragovi, A. Fuks, J. Makkerh, J.

Mort, C.P. Stanners, Self recognition in the Ig superfamily - Identification of precise subdomains in

carcinoembryonic antigen required for intercellular

adhesion, Journal of Biological Chemistry, 275 (2000)

26935-26943.

[3] X.L. Li, R. Yuan, Y.Q. Chai, L.Y. Zhang, Y. Zhuo, Y.

Zhang, Amperometric immunosensor based on toluidine

blue/nano-Au through electrostatic interaction for

determination of carcinoembryonic antigen, Journal of

Biotechnology, 123 (2006) 356-366.

[4] J. Wu, J. Tang, Z. Dai, F. Yan, H. Ju, N. El Murr, A

disposable electrochemical immunosensor for flow

injection immunoassay of carcinoembryonic antigen, Biosensors & Bioelectronics, 22 (2006) 102-108.

[5] J. Wang, Electrochemical biosensors: Towards point-

of-care cancer diagnostics, Biosensors & Bioelectronics,

21 (2006) 1887-1892.

[6] S.Y. Xu, X.Z. Han, A novel method to construct a

third-generation biosensor: self-assembling gold

nanoparticles on thiol-functionalized poly(styrene-co-

acrylic acid) nanospheres, Biosensors & Bioelectronics,

19 (2004) 1117-1120.

[7] D. Hernandez-Santos, M.B. Gonzalez-Garcia, A.C.

Garcia, Metal-nanoparticles based electroanalysis, Electroanalysis, 14 (2002) 1225-1235.

[8] J.M. Pingarron, P. Yanez-Sedeno, A. Gonzalez-

Cortes, Gold nanoparticle-based electrochemical

biosensors, Electrochimica Acta, 53 (2008) 5848-5866.




Custom fabricated MEMS-based Microgripper for Biological Cell

characterization

T. M. Khan1*, M. Yilmaz1, K. Topalli1, , and N. Biyikli1

1Bilkent University-UNAM, Institute of Materials Science and Nanotechnology, Ankara, Turkey

* Presenter: [email protected]

Abstract

We present Micro-Electro-Mechanical-Systems

(MEMS) based microgripper that is used for biological

cell characterization. The electrostatically actuated

microgripper is fabricated using a custom

microfabrication process which includes 3 mask

lithographic processes followed by non-conventional

jaw release methodology. The microgripper is tested for

micro-particles ranging from 10-30 µm size and a co-relation is established to further verify its effectiveness

in cell characterization using electrostatic comb sensing.

Introduction

MEMS-based microgripper is essentially a miniaturized

robotic hand. They have a number of applications

ranging from pick and place of micro-objects to material

characterization. Microgrippers can be actuated or

sensed used thermal, electrostatic and magnetic

techniques [1]. We use electrostatic comb drive with a

common ground to be used as both sensor and actuators. The conventional microfabrication of MEMS devices

include SOI-MUMPS (Silicon on Insulator-Multi user

MEMS Process) by MEMSCAP Inc. that are patterned

from both sides to release the structures and are further

diced. This adds a limitation to integration of structures

that are outlying the main chip area. A microgripper for

example, requires its jaws to reach out well outside the

actuation area to grasp the object. In order to overcome

this problem, we add custom patterns that can be

scribed off to suspend the jaws. Additionally a three

pronged jaw deign is introduced to actively release samples, after manipulation. The jaws are designed to

hold cells from 10-30 µm in size. The third beam works

as a plunger to remove adhered cells off the jaws to

make them usable again (Figure 1)

The fabrication process starts with a double side

polished SOI wafer with structural layer of 15 µm with

2 µm oxide and 500 µm of handle layer. Initially a

lithographic process is made followed by metal

deposition using e-beam evaporation and patterned via

lift-off for metal bonding. The top layer is then

patterned using standard lithography process and Dry

etch is achieved to reach the oxide layer (Figure 2). Wafer is then flipped and back side is patterned using

Deep Reactive Ion Etching (DRIE) in Inductively

Coupled Plasma (ICP). The Microgripper is then scribed

into smaller dies and then exposed to a Vapor HF

process to remove the underlying silicon dioxide layer.

In order to release the jaws, we introduced special

patterns that are used to scribe off the undesired areas.

The Microgripper is then bonded to a readout circuitry

to actively receive sensing output. The microgripper is

initially tested with polymer micro particles to better

understand the sensing mechanism before characterizing

biological cells.

The proposed custom fabrication for MEMS

microgripper is simple and effective for cell

characterization. The details of fabrication and

measurement results will be discussed in the full paper and at the conference.

Figure 1 Three pronged jaws to actively hold

Biological cells.

Figure 2 Microgripper with patterned top layer.

References

[1] Y. Jia and Q. Xu, “MEMS Microgripper Actuators

and Sensors: The State-of-the-Art Survey”, Recent Patents on Mechanical Engineering 2013, Vol. 6,

No. 2



NO gas sensing properties of CuO nanostructure at low operating temperature

Tuğba Çorlu1*, Irmak Karaduman1, Memet Ali Yıldırım2, Aytunç Ateş3 and Selim

Acar1

1 Department of Physics, Science Faculty, Gazi University, Ankara, Turkey

2Department of Electric Electronics Engineering, Engineering Faculty,

Erzincan University, Erzincan, Turkey

3Department of Material Engineering, Engineering and Natural Sciences Faculty, Yıldırım Beyazıt University, Ankara, Turkey


Abstract

Recently, much attention related to health care has been

growing as life expectancy is remarkably extended due

to the advancement of medical treatment and early diagnosis. As medical technologies develop, individuals

receive more medical benefits and expect more

convenient ways in diagnosis. According to the recent

developments of technology, physical conditions of

human body can be easily monitored by analyzing

biomarker gases from human breath [1]. Concentration

of these biomarker gases in exhaled breath of the patient

are prone to substantial increase compared to that in the

breath of healthy people. Among them, NO gas is a

critical marker of respiratory diseases [2]; the accurate

detection of NO in human breath can give early diagnosis of asthma and lung cancer. Therefore, NO

sensors with high sensitivity and fast response are

required for environment monitoring, combustion

emission control and human health diagnosis. Many

efforts have been made to develop NO sensors with

good performance [3].

Among the sensors investigated and developed, CuO

based sensors received much attention since they can detect a wide variety of gases with high sensitivity,

good stability and also low production cost [3]. Copper

oxide is a well-known p-type semiconductor with a

narrow band gap of 1.2 eV and has been extensively

studied becauseof its versatile applications, such as

catalysts, magnetic storagemedia, gas sensors, lithium

batteries, amperometric sensors, etc. Because the

practical performances of CuO nanomaterials are close related to its morphology and size, which ultimately

depends on the preparation methods and reaction

conditions , various methods have been developed to

synthesize CuO nanostructures, for example, thermal

oxidation of copperfoil, hydrothermal route, vapor-

liquid-solid synthesis, ultra sound irradiation, thermal

decomposition of precursors, SILAR, etc. [4]. The

SILAR method is low cost, simple and suitable for large

area deposition. Thin films can be used since the

deposition is carried out at or near to room temperature.

by Successive ionic layer adsorption and reaction

(SILAR) method with 15 cycle and investigated the gas

sensing properties. The gas sensing properties of the

CuO nanostructures were measured at different

operating temperatures and depending on different NO

and CO concentrations in air. It can be noted that the

sample exhibited acceptable response to 1 ppm NO gas

concentration. The possible sensing mechanism between the producing method and the sensing surface were

proposed.

Figure 1 SEM image of CuO film with 15 cycle

Acknowledgement: This work is supported by The

Scientific and Technological Research Council of Turkey

(TUBITAK) under Project No: 115M658 and Gazi

University Scientific Research Fund under Project No:

05/2015-09.

References

[1] A. Rydosz, A. Szkudlarek, Sensors 15, (2015) 20069-

20085

[2] Y. B. Li, Z. W. Huang, S. Q. Rong, Sensors Materials

18 (2006) 241-249

[3] Z. –X Cai, H. –Y. Li, X. –N. Yang, X. Guo Sens.

Actuators B 219 (2015) 346-353

[4] M. A. Yıldırım, Y. Akaltun, A. Ateş Solid State

Sciences 141 (2012) 1282-1288




Improvement of Immobilization and Spotting Techniques of Biosensors

Including Oligonucleotid Probe

Yagmur Guler1*, Mert Muhammed Koc1, Merve Kucukoflaz 1, Şengül Kurtuluş 1, Mehmet Ali Boz1 and Mustafa

Oguzhan Caglayan1



1.Introduction

DNA microarray technologies have been used in

molecular biology since 20 years. With the

improvement of this technology, the new applications

techniques like protein microarray techniques, cells on

chips and comparative genomic hybridization have also

been used and new integrated devices like micro total

analysis systems (µTAS) and lab-on-a-chip have been

improved. However, these techniques often face some

reliability problems. In order to use DNA series

optimally, during the analytical application the actual situations and the physicochemical events for each

operation must be understood exactly. The most

important step during biosensor production is the

volatilization of the solvent in immobilization step,

irrespective of the analytical method being used. During

volatilization, ODN concentration in the droplet

increases and as a result, the immobilization kinetics

accelerates. During the volatilization of the droplet, by

dispersion of the ODNs in the droplet/ spot irregularly,

the cyclic morphology of spot occurs in demilunar or

any kind of undesired form. These kinds of

inhomogenities in and between spots cause errors in obtaining sensor signals and interpreting the results. The

most ideal case is each spot should be similar to

immobilized ODN probe and dispersed uniform.

2.Materials and Methods

In the presented project, for determining the appropriate

immobilization conditions, researching the conditions of

the spots volatilization on microarrays is being purposed

considering both the material interactions between

probe – base and direct adsorption situations. The

project were completed by improving the conditions of

the immobilization of the probes (ODN and/or protein probe) on to substrate modified by self-assembled

monolayers which reacts with these different reactive

groups by using (micro)spotting techniques; developing

a general mechanism for commercial ODN probes

which are approximately 30 base pair (bp) and

determination of the general volatilization conditions;

improving the volatilization conditions by adding non-

Newtonian fluids (polymeric components and/or

nanofluids) in the solution forming the ODN probes and

researching the volatilization conditions and

immobilization kinetics; and finally, by providing the

most appropriate geometry and spotting conditions for non-Newtonian fluids added ODN solutions.

3.Results

After obtaining function using droplets of the Young-

Laplace equation modeling it was performed and the

modeling results with measurement results with

functions with droplets function were compared.

Comparative process was performed on the contact

angle values are obtained. This method was carried out

with the contact angle measurements are obtained using

different fluids on the Si substrate compared to the

normal measurement process.

Table 1 The contact angle which was obtained by using

different fluids and Si substrates values and standard

deviation values (not including modeling)

Base Material

Fluid Left Right Average

Si wafer %80 Tripropylene glycol - %20 water

38.1±2.4 39.4±2.6 38.6±2.6


59.6±2.6 57.4±2.7 58.2±2.9


68.9±2.9 69.1±2.8 68.3±2.4


78.4±2.8 80.1±2.2 79.1±2.4

Table 2 The contact angle which was obtained by using

different fluids and Si substrates values and standard

deviation values(including Young- Laplace modeling)

Base Material

Fluid Left Right Average

Si wafer %80 Tripropylene

glycol - %20 water

37.3±1.2 38.1±1.6 37.7±1.1


57.3±1.3 57.4±1.7 57.2±1.2


66.3±0.9 66.1±0.8 66.2±0.6


76.2±0.8 76.5±1.2 76.1±0.9

In this Project results were obtained: Droplet model

obtained by solving the equation was used to Young-

Laplace using contact angle measurement on different

substrates. Droplet model with the measurement results

obtained contact angle was seen with ow Standard

deviation of 2σ’s. There is a significant relationship

between the kinetics of ODN probes immobilized by contact angle measurements. In studies that use TRIS an

PBS buffer solutions which SH functional end on the Au

surface as stated in the literatre TRIS buffer

immobilization of ODN probes was observed that a

beter performance. A biolgical agent such as Tween 20,

the use of immobilization solution increases the

immobilization rate. The effects of nanoparticles, in all

the buffer solution may be for interacting with the

tertiary structure ODN. The most important output of

the project, diffirent substrate is also suitable for an

improved measurement method.



Preparation and Characterization of Graphene/Conducting Polymer

Composites Coated Surfaces

Yaşar Bayramlı1*, Filiz Kuralay1 and Bora Garipcan2


2Institute of Biomedical Engineering, Boğaziçi University, 34684 Istanbul, Turkey


Abstract

Conducting polymers (CPs) are organic polymers that

conduct electricity. They are of quite importance with

respect to various materials in terms of application since they have unique electrical and optical properties. These

polymers have porous structures and high surface areas.

According to their oxidation states and doped/undoped

forms, their volumes change. Thus, conducting

polymers are widely used in many areas such as

biochemistry, medicine, pharmacy and nanotechnology.

Electropolymerization of their monomers result in

polymer films, which are uniform and strongly adherent

to the electrode surface [1,2].

Graphene (GR) is a single layer of carbon atoms packed

into a two-dimensional honeycomb lattice. Graphene-

based nanomaterials have drawn considerable interest

due to its unique physicochemical, thermal and

mechanical properties including large specific surface

area, excellent electrocatalytic activity, good electrical

conductivity, high mobility of charge carriers and

unique transport performance. It has been a great

potential for various researches, such as electrochromic

devices, lithium batteries, supercapacitors, solar cells and sensing devices [3,4].

In this study, preparation of graphene/conducting

polymer nanocomposites coated electrodes were

achieved using cyclic voltammetry (CV) and constant

potential electrolysis. For the electropolymerization

process, pyrrole and 3,4-ethylenedioxythiophene

monomers were used. Thus, graphene/polypyrrole and graphene/poly(3,4-ethylenedioxythiophene) coated gold

electrode (AuE), platinum electrode (PtE) and glassy

carbon electrode (GCE) were obtained. The

electrochemical behaviors of the coated surfaces were

examined with cyclic voltammetry and electrochemical

impedance spectroscopy (EIS). Various cyclic scans and

electropolymerization times were used in order to

investigate the changes in the electrochemical behaviors

of the coated electrodes. We believe that the coated

electrodes later on can be used for different applications

such as biosensing and biofuel cell applications.




References

[1] F. Kuralay, A. Erdem, Analyst 140 (2015) 2876-

2880.

[2] F. Kuralay, H. Özyörük, A. Yıldız, Sensors and

Actuators B: Chemical 109 (2005) 194-199.

[3] M. Pumera, The Chemical Record 9 (2009) 211-223.

[4] B. Pérez-López, A. Merkoçi, Microchimica Acta

179 (2012) 1-16.


http://link.springer.com/article/10.1007/s00604-012-0871-9#author-details-1

http://link.springer.com/article/10.1007/s00604-012-0871-9#author-details-2


Sensitive Determination of Ceftizoxime by Graphene Oxide/Gold Nanoparticle

Modified Pencil Graphite Electrode

Yeşim Tuğçe Yaman1*, Ceren Yardımcı2 and Serdar Abacı3

1 Department of Chemistry, Graduate School of Science and Engineering, Hacettepe University,

Ankara, Turkey 2Department of Analytical Chemistry, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey

3Department of Chemistry, Faculty of Science, Hacettepe University, Ankara, Turkey


Introduction

Ceftizoxime (CFX), is the third generation

cephalosporin antibiotic. It interferes the formation of

the bacterium’s cell wall causing the wall to rupture

which results the death of bacteria [1]. There are many

studies that have been published regarding the detection

and analytical control of CFX by chromatographic and

spectroscopic methods which are highly sensitive and

have low detection limit, they have high costs, a time-

consuming process and require trained technicians.

Because of these drawbacks in this study, determination

of CFX was performed by electrochemical methods.

Method

Cyclic voltammetry (CV) was performed for identifying

oxidation peak of CFX and to show the effect of

modified electrode for the peak current response of

CFX. Square wave anodic stripping voltammetry

(SWASV) was recorded from the 0.6 V to 1.0 V (vs.

Ag/AgCl) after 300 seconds and 0.6 V (vs. Ag/AgCl)

accumulation time and deposition, respectively. Square

wave voltammetry parameters were examined. The

optimized values were amplitude 4 mV, pulse size 50

mV, frequency 50 Hz.


Surface morphology of bare and modified electrodes

was performed by scanning electron microscopy (SEM).

Fig.1.a shows that bare PGE surface has irregular

graphite layer. Because of the GO sheet entangled with

each other, the single- or few-layer GO nanosheets were

with lots of wrinkles (Fig.1.b). When AuNP was

deposited onto the PGE by electrolysis, AuNP was

formed as spherical structure (Fig.1.c,d).

Figure 1. SEM images of a) Bare PGE, b) GO modified PGE, c) AuNP modified PGE, d) AuNP/GO modified

PGE. (Magnitude: 35000)

The electrochemical behavior of CFX was investigated

by cyclic voltammetry (CV) at bare and modified PGE

surfaces. (Figure 1).

Figure 2. Cyclic voltammogram of 50 µM CFX at (a)

bare, (b) GO modified, (c) AuNP modified, (d)

AuNP/GO modified PGE. (e) blank solution pH 3 BRT.

(Scan rate:100 mVs-1)

In Figure 2, after the surface modification with

AuNP/GO, oxidation peak current of CFX was

increased. This result shows the catalytic effect of

AuNP/GO surface on the CFX oxidation peak current.

Parameters affecting the experimental conditions, such

as the electrodeposition time of AuNP, physical

adsorption time of GO, pH, accumulation time, deposition potential, etc., were investigated for the

maximum performance of the electrode. Under

optimized conditions, the limit of detection and the limit

of quantity were found to be 0.4 nM and 1.2 nM for

CFX, respectively. This new sensor system offered the

advantages of simple fabrication, low cost, fast

response, high sensitivity, low background current and

low detection limit for CFX. This new sensor system

was successfully tested for the quantitative detection of

the CFX in a pharmaceutical preparation.

Acknowledgement: The authors thank to Research

Council of Hacettepe University for financially supporting to this study (THD-2015-7394).

References

[1] S. Shahrokhian, S. Ranjbar, M. Ghalkhani,

Electroanalysis. 28 (2016) 469–476.




Modeling of a Photonic Crystal Fiber Based Dye Laser

Z. Rashida, K. Çiçeka, and A. Kiraza,b*

a Koç University, Department of Physics, Sariyer, Istanbul

b Koç University, Department of Electrical and Electronics Engineering, Sariyer, Istanbul

*Preenter:: [email protected]

Abstract

Photonic crystal fiber (PCF) is a new class of

microstructured optical devices which confine and

guide light by the structural modifications and not

only by the refractive index contrast. PCFs are

finding applications in highly sensitive gas sensors,

biesensors and fiber lasers because of augmented

light matter interaction in the transparent core or the

neighbourhood. PCF is a promising technology for enhancing the power levels of fluidic lasers because

of its increased flexibility in singlemode core sizes,

the increased numerical aperture of pump cores in

doubleclad fiber configurations and the high

thermal stability of lowloss allglass structures.

Associated with less bending loss, controlled

dispersion and variable group velocity, the use of

photonic crystal fibers as host medium for the active

biological gain medium to develop a fiber laser

opens new prospects due to photobleaching and self

healing in the field of biophotonics.

We present a mathematical model of a PCF

laser based on coupled first order rate equations

incorporating rhodamine B dye as a gain medium in

the air cladding region of the suspended core PCF.

The mode profile of the pump and signal is

examined by finite element method which is used to

calculate the effective mode index and pump and

signal filling factors. We analyze the behavior of the system under different dopant concentration, length

of the fiber, scattering loss at pump and signal

wavelengths and input pump power. The parametric

study, as a result, computes the threshold pump

power, slope efficiency, pump and signal power

distribution in both directions, fraction of number of

atoms in upper level of the energy state and

optimum length.



Amperometric Uric Acid Biosensor Based on Magnetite Nanoparticles Modified

Carbon Paste Electrode

Z.Ö.Erdoğan1*, S.Küçükkolbaşı1, P.E.Erden2 and E. Kılıç2

1Department of Chemistry, Faculty of Science, Selcuk University, 42075 Konya, Turkey 2Department of Chemistry, Faculty of Science, Ankara University, 06100 Ankara, Turkey


Abstract

Uric acid (2,4,6-trihydroxypurine) is an end product

from purine derivatives in human metabolism.

Abnormal levels of uric acid in biological fluids is a

symptom of many diseases such as gout, hyperuricemia,

diabetes, renal disease and Lesch-Nyhan syndrome.

Therefore, fast and reliable determination of uric acid in

biological fluids is routinely required for diagnosis and

treatment. [1]. Various methods, including

spectrophotometry, enzymatic testkits, high-

performance liquid chromatography, capillary electrophoresis, chemiluminescence and

electrochemical techniques, is used for the detection of

uric acid. Nevertheless, most of these methods are very

laborious, expensive, time-consuming and/or complex

to perform [2, 3]. Among these methods, especially

electrochemical technique for the determination of uric

acid is very interesting, because this technique directly

provides real-time and on-line data analysis without

need for pre-seperation process.

Figure 1 Uric Acid

In this study, carbon paste enzyme electrode based on

Fe3O4 nanoparticles for uric acid determination was

fabricated. The carbon paste electrode was prepared by

mixing magnetite nanoparticles (Fe3O4), uricase

enzyme, graphite powder and paraffin oil and the paste

was placed into a teflon electrode body. Electron

transfer properties of unmodified and Fe3O4

nanoparticles modified carbon paste electrodes were investigated by cyclic voltammetry.

The voltammetric study indicated that the presence of

Fe3O4 nanoparticles results in increased electroactive

surface area and enhanced electron transfer. The

parameters affecting the analytical performance of the

enzyme electrode such as enzyme loading, nanoparticle

amount, pH, buffer concentration and working potential

were investigated. Analytical characteristics of the presented biosensor were also studied. The working

range of the enzyme electrode was 1-1000 μM,

detection limit was 1μM and response time was 50 s.

Figure 2 The mechanism of the biosensor

In conclusion the cost of the biosensor is low and its

fabrication process is very simple. The biosensor exhibit good operational and storage stability. Therefore, the

presented biosensor offers a good promise for practical

applications in real samples. Our future study will be

focused on the the use of the enzyme electrode for uric

acid determination in real samples.

References:

[1] K. Jindal, M. Tomar, V. Gupta, Biosensors and

Bioelectronics 38 (2012) 11-18.

[2] J. Arora, S. Nandwani, M. Bhambi, C.S. Pundir,

Anal. Chim. Acta 647 (2009) 195-201.

[3] Erden, P.E., Kılıç, E., Talanta, 107, (2013) 312–323.



Electrodeposition and Characterization of Cu3Te2Te2 Thin Films

ZehraYazar Aydın1* and Serdar Abacı2

1Hacettepe University, Graduate School of Science and Engineering, Department of Nanotechnology

and Nanomedicine, Ankara, Turkey 2Hacettepe University, Faculty of Science, Department of Chemistry, Ankara, Turkey


Introduction

Today, synthesis of compound semiconductors is both

technologically and scientifically very important

because of many applications in the optoelectronic and

high efficiency solar cells. Thin chalcogenide films are

of particular interest for the fabrication of large area

photodiode arrays, solar cells, photoconductors, sensors, etc [1]. This study, Cu3Te2Se2 nanofilms were

synthesized using underpotential deposition (UPD)

based electrochemical codeposition from the same

solution at constant potential.

Method

Cu3Te2Te2 nanofilms were synthesized by the UPD-

based electrochemical codeposition technique at room

temperature from a solution containing both Cu+2 and

HTeO2+, H2SeO3. Cyclic voltammetry and potential-

controlled electrolysis methods were used for the

electrochemical characterization. Cu3Te2Se2 thin films were deposited via potential-controlled electrolysis on

Au plate. The synthesized nanofilms were characterized

by X-ray diffraction (XRD) and X-ray photoelectron

spectroscopy (XPS).


The electrochemical behaviors of Cu, Te, Se and

Cu3Te2Se2 system in the UPD and bulk regions were

investigated on polycrystalline Au electrodes by cyclic

voltammetry measurements (Figure 1).

Figure 1. a) Cyclic voltammograms 0.1 M H2SO4 at pH

0.5 on Au electrode. 2 mM CuSO4 (black), 2 mM TeO2

(red) and 0,2 mM SeO2 (green) b) Cyclic

voltammogram recorded in 0.1 M H2SO4 (blank

solution) for CuTe deposited at 0.1 V electrolysis (blue)

Figure 2 shows the 20°–80° 2θ range of the XRD pattern of the CuTe nanofilm deposited at 0.2 V onto an

Au substrate.

Figure 2. XRD pattern of a Cu3Te2Se2 nanofilm

deposited onto an Au substrate.

XRD results showed that the Cu3Te2Se2 films are crystalline and a single phase (Figure 2).

The stoichiometric ratios of the components in the

deposited films were determined via XPS. According to

calculations based on the XPS data, the Cu:Te:Se ratio

in the deposited films is approximately 3:2:2.

Consequently, the synthesis of copper chalcogenides

nanofilms using underpotential deposition (UPD) based

electrochemical codeposition method can be inexpensively and easily performed under atmospheric

conditions without requiring difficult-to-use and

expensive equipment.

Acknowledgements: This work was funded by the


Turkey (TUBITAK) under project number 138366

References

[1] Sakr, G.B., Yahia, I.S., Fadel, M., Fouad, S.S.,

Romcevic, N. 2010. Journal of Alloys and Compounds.

507, 557–562.



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