Polymer Modified Carbon Fiber Microelectrodes and Multielectrode Arrays for Multiplexing Neurochemical Measurements
We have developed novel methods to detect neurotransmitters and their metabolites. Traditionally, carbon-fiber microelectrodes (CFMEs) have been utilized to detect dopamine, serotonin, and other important neurotransmitters. However, this method is limited due to a low sensitivity to detect physiologically relevant concentrations of these neurotransmitters. Polymer modified microelectrodes will be utilized to detect fast changes of neurotransmitters. Furthermore, novel electrode coatings and waveforms will also be utilized to detect several neurotransmitter metabolites such as 3,4-dihydroxy-benzeneacetaldehyde (DOPAL), 3-methoxytyramine (3-MT), and 3,4 dihydroxyphenylacetic acid (DOPAC). There is no current assay to detect metabolites of dopamine utilizing voltammetry. Through waveform modifications and polymer electrode coatings, we develop a novel method for dopamine metabolite detection utilizing fast scan cyclic voltammetry (FSCV), which will help differentiate the cyclic voltammograms of dopamine and dopamine metabolites through the shapes and positions of their respective cyclic voltammograms. Preliminary measurements have been made in zebrafish retina ex vivo. We have also developed multielectrode arrays (MEAs) for neurotransmitter detection with FSCV in multiple brain regions simultaneously. Parylene and silicon insulated CFME arrays measured neurochemicals in multiple brain regions simultaneously when coupled with multichannel potentiostats. Moreover, we have utilized techniques such as plasma enhanced chemical vapor deposition to deposit conductive carbon nanospikes onto the surface of existing metal multielectrode arrays to give them dual functionality as neurotransmitter sensors with FSCV in addition to being used primarily for electrical stimulation and recording. Other assays have shown the utility of electrodepositing carbon nanotubes and polymers such as PEDOT to coat metal arrays with carbon to give them dual sensing capabilities.