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A Method for Systematic Electrochemical and Electrophysiological Evaluation of Neural Recording Electrodes
Published on: March 3, 2014
Chronically Implanted, Nafion-Coated Ag/AgCl Reference Electrodes for Neurochemical Applications
Parastoo Hashemi1, Paul L Walsh, Thomas S Guillot
1Department of Chemistry, University of North Carolina at Chapel Hill, NC 27599.
ACS Chemical Neuroscience
|November 30, 2011
Summary
Coating silver-silver chloride reference electrodes with Nafion polymer stabilizes dopamine measurements in rats for up to 28 days. This method prevents electrochemical potential shifts caused by glial encapsulation, improving brain electrochemistry research.
Area of Science:
- Neuroscience
- Electrochemistry
- Biomaterials
Background:
- Fast-scan cyclic voltammetry (FSCV) measures dopamine in freely moving rats.
- Chronic implantation of Ag/AgCl reference electrodes causes potential shifts, affecting dopamine detection.
- These shifts, often >0.2 V, occur within days of implantation.
Purpose of the Study:
- To optimize Nafion coating on Ag/AgCl reference electrodes to prevent potential shifts.
- To assess the long-term stability of Nafion-coated electrodes.
- To investigate the interaction between reference electrodes and brain tissue.
Main Methods:
- Coating sintered Ag/AgCl reference electrodes with Nafion.
- Long-term implantation and electrochemical measurements in rats.
- Immunohistochemistry, EDS, SEM, and impedance spectroscopy to analyze electrode-tissue interface.
Main Results:
- Nafion coating stabilized reference electrodes for up to 28 days.
- Nafion coating reduced glial cell adsorption and plaque formation compared to bare electrodes.
- Glial encapsulation did not increase electrode impedance, indicating the shift is chemical, not resistive.
Conclusions:
- Nafion coating effectively prevents electrochemical potential shifts in Ag/AgCl reference electrodes.
- This stabilization is crucial for reliable, long-term dopamine monitoring using FSCV.
- The coating mitigates adverse tissue reactions, ensuring data integrity in brain electrophysiology.
