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Gold Nanoparticle-Modified Carbon Fiber Microelectrodes for Enhanced Neurotransmitter Detection

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posted on 2023-08-04, 09:02 authored by Durga Sanuja Mohanaraj

Carbon-fiber microelectrodes (CFMEs) are the standard biosensors for neurotransmission detection due to their biocompatibility, size, and electrochemical properties. However, unmodified CFMEs have been known to have several limitations for neurotransmitter detection with fast-scan cyclic voltammetry (FSCV). Because carbon-fiber microelectrodes are mostly composed of basal plane carbon, unmodified-electrodes have relatively low electroactive surface areas that lead to poor sensitivities. Additionally, surface fouling may occur with certain neurochemicals that could potentially obstruct further neurotransmitter adsorption onto the electrode surface. These days, there has been an emphasis on improving the sensitivity of CFMEs, and the most widespread method of enhancing electrode functionality is by coating the fiber surface with a conductive polymer or another form of carbon. In the present work, the electrochemical performance of CFMEs for neurochemical measurements is enhanced by electrodepositing gold nanoparticles (AuNP) onto the fiber surface using electrodeposition and cyclic voltammetry. Gold is an ideal electrode material for neurochemical detection as it is a stable, conductive, and relatively inert metal. The modified-electrodes possess improved sensitivity of neurochemical detection than unmodified electrodes. The thin and uniform layer of gold nanoparticles on the fiber-surface increases electroactive surface area for neurotransmitter adsorption, which leads to considerably higher peak oxidative currents and lower limits of detection. The potential separation of the oxidation and reduction peaks (∆Ep) of the AuNP-CFMEs is smaller, suggesting higher conductivity and faster electron transfer kinetics which is ideal for measuring phasic firing of dopaminergic neurons and fast neurochemical changes in the brain. Furthermore, the coated-electrodes also possess uniform stability for dopamine detection for over a four-hour period which is the typical time period for ¬in-vivo experiments. This is significant as it denotes the potential applicability of the AuNP-CFMEs for in-vivo¬ testing. Additionally, a linear rise in peak oxidative currents is observed with the AuNP-modified electrodes with regards to both dopamine concentration and scan rate, indicative of dopamine adsorption control to the electrode surface. However, an asymptotic curve is seen with higher dopamine concentrations suggesting that dopamine is now saturated at the electrode surface with more diffusion control taking place. This study has a myriad of applications for enhanced neurochemical detection and is crucial for the development of novel electrode sensors for in-vivo neurotransmitter measurements to analyze the neurochemical effects of drug abuse and other psychostimulants, Parkinson’s disease, depression, and other behavioral conditions.

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American University

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Degree Awarded: M.S. Chemistry. American University

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http://hdl.handle.net/1961/auislandora:84448

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