By Alexander Zestos, Assistant Professor of Chemistry, American University
The brain is by far the most heterogeneous organ, and it is critically important to monitor various brain regions simultaneously in order to understand complex pharmacological, drug, and behavioral states. High temporal resolution neurochemical measurements must be made to study the phasic firing of neurons in several brain regions concurrently. Fast scan cyclic voltammetry (FSCV) and carbon-fiber microelectrodes (CFMEs) have been utilized used to detect several important neurochemicals in vivo. This work will also discuss the development of carbon fiber multielectrode arrays (MEAs) for neurotransmitter detection with FSCV in multiple brain regions simultaneously. Parylene and silicon insulated carbon fiber microelectrode 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 (PECVD) 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. Carbon multielectrode arrays performed comparably to single channel CFMEs. We were able to apply four different waveforms to four different electrodes simultaneously. Furthermore, we also measured neurotransmitter release in brains slices using the four-channel carbon fiber array. Making multiplexed measurements of multiple brain regions simultaneously will help understand complex brain heterogeneity.