Introduction to Biomaterials Science - Aalto to Biomaterials Science Emilia Peltola, DSc 7.9.2015. 4...
Transcript of Introduction to Biomaterials Science - Aalto to Biomaterials Science Emilia Peltola, DSc 7.9.2015. 4...
4
Introduction 1/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Introduction to BiomaterialsScience
Emilia Peltola, DSc
7.9.2015
4
Introduction 2/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Contents
Practicalities
Biomaterials & biocompatibility
Protein adsorption
Criteria for the selection of biomaterials
4
Introduction 3/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
ELEC-E8724 Biomaterials Science
Responsible teacher Emilia Peltola (@aalto.fi)Several visiting lecturers
I Lectures mon/thu 12:15 – 14:00, I-periodI Seminars mon/thu 12:15 – 14:00, 12.-23. Nov
Course requirementsI 4 home assignments (a grade in each is required)I Seminars (seminar work & peer review &
participation into minimum two seminars)I Home exam
Grading: Home assignments (1/3), seminar (1/3),home exam (1/3)
4
Introduction 4/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Course book
Ratner et al., BiomaterialsScience – An Introductionto Materials in Medicine,3rd edition, 2013(available as E-book)
Applicable parts (listed atthe end of slides) only!
4
Introduction 5/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Course aims
I differentiate the biomaterials in medicine and theircentral properties
I understand the requirements set by thebiomedical applications
I know biomaterial-tissue interactionsI comprehend how to modify biocompatibility
4
Introduction 6/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Biomaterials & Biocompatibility
4
Introduction 7/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Brainstorming I
What kind of implants can you name?
http://presemo.aalto.fi/biomaterials/
4
Introduction 8/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Definition of biomaterials
A biomaterial is a material intended to interface withbiological systems to evaluate, treat, augment, orreplace any tissue, organ or function of the body.
ESB Consensus Conference II
4
Introduction 9/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Applications
Biomaterials are integrated into biomedical devices toimprove quality of life
i.e. biomaterials keep the legs moving, heart beating,ears hearing, blood flowing, eyes seeing.
4
Introduction 10/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Examples of biomaterials
Metals Polymers Ceramics Biologicalmaterials
e.g. titanium, e.g. UHMWPE, e.g. alumina, e.g. chitin,stainless steel PMMA bioglass nacre
4
Some history
Sutures(linen,catgut)
Goldin den-tistry
Nacretooth
implant
Pumpsandcell
culture
Intraocularlenses
Hipprost-heses
Vascularprost-heses
Artificialheart,kidney
30,000 B.C. 600 B.C. 1940s 1950s
4
Introduction 12/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Biocompatibility
First generation of implants (1940–80): chemicallyinert materials
I non-toxic, non-immunogenic, non-thrombogenic,non-carcinogenic, non-irritating etc.
Definition was insufficient, because...
1. the host response depends on the application2. biodegradable applications were needed3. bioactive applications were needed
Williams 1987: ”the ability of a material to perform withan appropriate host response in a specific application”
I new kind of applications (tissue engineering, etc.)require more specific definition→
4
Introduction 13/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Definition of biocompatibility
”Biocompatibility refers to the ability of a biomaterial toperform its desired function with respect to a medicaltherapy, without eliciting any undesirable local orsystemic effects in the recipient or beneficiary of thattherapy, but generating the most appropriatebeneficial cellular or tissue response in thatspecific situation, and optimising the clinicallyrelevant performance of that therapy.”
[Williams, 2008]
4
Introduction 14/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterialsBiocompatibility and different applications
Exercise 1
4
Introduction 15/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Some applications
Application Number/Year – WorldJoint replacements 2,500,000Blood vessel prosthesis 200,000Heart valve 400,000Pacemaker 600,000Implantable defibrillator 300,000Stent 1,500,000Catheter 1,000,000,000Contact lens 150,000,000Intraocular lens 7,000,000
[Ratner et al., 2013]
4
Introduction 16/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Some applications - fail
Application StateJoint replacements still a 10-15 yr lifetimeBlood vessel prosthesis no healingHeart valve calcification or thrombosisPacemaker electrode encapsulationImplantable defibrillator electrode encapsulationStent clotting and closureCatheter thrombosis, infectionContact lens discomfort and eye injuryIntraocular lens 25%-50% reoperation rate
4
Introduction 17/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Metals Polymers Ceramics Biologicalmaterials
e.g. titanium, e.g. UHMWPE, e.g. alumina, e.g. chitin,stainless steel PMMA bioglass nacre
What is the similarity between all these widelydifferent materials?
They all have uncontrolled interfacial proteins!
4
Introduction 18/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Protein adsorption consequences
Protein adsorption is energetically favourable
Protein adsorption influencesI activation of complementI blood clottingI bacteriaI cellsI implant functionality
Due to the adsorption the concentration of proteinsmay be a thousand fold higher compared to thesurrounding tissue fluid
4
Introduction 19/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Protein adsorption
Proteins come into contact with the surface throughthese mechanisms:
I diffusionI thermal convectionI bulk flowI a combination thereof
4
Introduction 20/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Modelling of protein adsorption
Concentration, speed and molecular size of theprotein are important variables when modellingadsorption
Fick II:
dndt
= C0(Dπt
)1/2 (1)
where n is concentration of proteins at the interphase,C0 is the concentration of proteins at bulk, D is thediffusion coefficient ja t is time
4
Introduction 21/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Vroman effect
4
Introduction 22/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Structure of proteins
[Griffths et al., 2000]
4
Introduction 23/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Proteinin adsorption is affected by
I The size, charge, amphiphatic nature and stabilityof the protein
I The topography, charge, chemistry andmicrostructure of the surface
I The amount of the protein close to the surface
[Andrade et al., 1992]
4
Introduction 24/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
An example of the size effect
[Dee et al., 2002]
Fibrinogen (340 kDa) 703contacts/molecule
Albumin (67 kDa)77 contacts/molecule
4
Introduction 25/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Example of the structural stability of theprotein
[Thevenot et al., 2008]
4
Introduction 26/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
The role of surface in protein adsorption
Topography Available area for adsorptionChemistry Molecular interactionWettability Hydrophobic interaction strongerHeterogenity Wider scale of
possible interactionsCharge Attraction &repulsionElasticity Possible effects on conformation
4
Introduction 27/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Proteins affect surface
Proteins may damage the surface of a biomaterialI Crevice corrosionI Secretions of cellsI Calcium ions
4
Introduction 28/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Brainstorming II
What kind of issues you need to consider whenyou select a biomaterial for an implant?
http://presemo.aalto.fi/biomaterials/
4
Introduction 29/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Criteria for the selection of biomaterials
Criteria for the selec-tion of biomaterials
Physicalproperties
Biologicalfixation
propertiesCan be
purified, fa-bricated and
sterilizedeasily
Maintainsthe desiredpropertiesin vivo for
the requiredperiodof time
Does notinduce
undesirablehost-implant
reactions
4
Introduction 30/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterialsMuddy cards
4
Introduction 31/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Next time: Properties of materials
I Why are metals, ceramics and polymers different?I Bulk properties and their relevance for implantsI Surface properties and their relevance for
implants
4
Introduction 32/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Seminar topics
Find a pair and choose your topic at MyCourses.
I Smart metals as biomaterials ( Pair 1)I Smart polymers as biomaterials ( Pair 2)I Recent tissue engineering applications (Pair 3)I Biomaterials controlling neurogenesis (Pair 4)I Predicting implant integration with in vitro
experiments (Pair 5)I Biocompatibility challenges in brain (Pair 6)I In vitro testing platforms e.g. artificial lung (Pair 7)I Tissue-integrated sensor (Pair 9)I Non-fouling sensors (Pair 10)I Biomaterials in stimulating biolectrodes (Pair 11)
You may also suggest a topic of your own.
4
Introduction 33/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
References
Andrade, J. D., Hlady, V., and Weibel, A. P. (1992).Adsorption of complex proteins at interfaces.Pure & Appl Chem, 64:1777–1781.
Dee, K. C., Puleo, D. A., and Bizioz, R., editors (2002).An Introduction to Tissue-Biomaterial Interactions.Jon Wiley & Sons.
Griffths, A. J. F., Miller, J. H., T.Suzuki, D., Lewontin, R. C., and Gelbart, W. M. (2000).An Introduction to Genetic Analysis.W. H. Freeman and Company.
Ratner, B. D., Hoffman, A. S., Schoen, F. J., and Lemons, J. E., editors (2013).Biomaterials Science An Introduction to Materials in Medicine.Elsevier.
Thevenot, P., Hu, W., and Tang, L. (2008).Surface chemistry influences implant biocompatibility.Curr Top Med Chem, 8(4):270–280.
Williams, D. F. (2008).On the mechanisms of biocompatibility.Biomaterials, 29(20):2941–2953.
4
Introduction 34/ 34
Emilia Peltola, DSc
Practicalities
Biomaterials &biocompatibility
Protein adsorption
Criteria for the selectionof biomaterials
Course book:
I Introduction - Biomaterials ScienceI A History of BiomaterialsI Chapter I.1.1 - Introduction: Properties of
MaterialsI Chapter II.1.2 - Adsorbed Proteins on
BiomaterialsI Chapter III.1.2 - Sterilization of Implants and
Devices