Katy Fordyce Department of Chemistry Corvallis, OR 97330 Mentor: Dr. Alexey Shvarev
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Transcript of Katy Fordyce Department of Chemistry Corvallis, OR 97330 Mentor: Dr. Alexey Shvarev
Electrochemical Nonseparation Binding/Immunoassays Based
On Solid-State Reversible Polyion Selective Sensors
Katy FordyceDepartment of Chemistry
Corvallis, OR 97330Mentor: Dr. Alexey Shvarev
Electrodes (ISEs)
~ Conduct current through a cell
~ Used to detect specific species
~ Applying new method
Advantages Over Old Methods
~ Nondestructive
~ Noncontaminating
~ Short response time
~ Can be designed for selectivity
~ Unaffected by color or turbidity
Species of Interest
1. Protamine
~ Avg. charge = +20
~ Peptide
~ Arginine Rich
O
NHNH
ONH
O
NH NH2+
NH2
(CH2 )3
NH NH2+
NH2
(CH2 )3
NH NH2+
NH2
(CH2 )3
2. Trypsin
~ Peptidase
~ Specific for Arginine
How Trypsin Is Used
= Protamine
= Trypsin
= Other Species
•For more information about Cystic Fibrosis, please visit www.cff.org
Basic SCE Design
• PVC body
• Graphite core
• Conducting polymer~PEDOT
• Ion selective membrane
~Hydrophobic
Cross Section View:
Membrane Composition: Important!
• Selectivity = Ion exchanger (DNNS+)
Membrane
H+ DNNS-TDDA+
SO3
-
C9H19
C9H19
N
+
C12H25
C12H25C12H25
C12H25
Tetradodecylammonium Dinonylnaphthalenesulfonate
How Do Reversible SCE’s Work?
1. Constant Current
SCE
= Protamine ions
= Na+ ions
SCE
= Protamine ions
= Na+ ions
2. Stripping Current
How Do Reversible SCE’s Work?
Question:Can the method described earlier be used to
detect the enzyme activity of trypsin?
Research Goals:1. Construct electrodes which are
selective for protamine
2. Test the electrodes in a trypsin solution to monitor enzyme activity
Data Collection
Note: Both graphs share the same x-axis!
Measuring Trypsin Response
0 100 200 300 400 500 600-0.01
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
E,
V
Time, s
Units / mL 0 10 30 50
Baseline
Protamine
Trypsin
Calculating Trypsin’s Activity
Step 2. The slope will equal the k, the reaction rate
Step 1. Convert potential Concentration
EXAMPLE
0
2
4
6
0 2 4 6
Time
ln(A
/A0)
k
In Summary
Membrane
DNNS-TDDA+
Acknowledgements
~ Dr. Alexey Shvarev
~ Hasini Perera
~ Dr. Kevin Ahern
~ Group 4
~ The Howard Hughes Medical Institute