Review of fast scan cyclic voltammetry and multiplexing neurochemical detection with carbon fiber multielectrode arrays

Fast scan cyclic voltammetry (FSCV) is an analytical technique that was first developed over 30 years ago. Since then, it has been extensively used to detect dopamine using carbon fiber microelectrodes (CFMEs). More recently, electrode modifications and waveform refinement have enabled the detection of a wider variety of neurochemicals including nucleosides such as adenosine and guanosine, neurotransmitter metabolites of dopamine, and neuropeptides such as enkephalin. These alterations have facilitated the selectivity of certain biomolecules over others to enhance the measurement of the analyte of interest while excluding interferants. In this thesis, we detail these modifications and how specializing CFME sensors allows neuro-analytical researchers to develop tools to understand the neurochemistry of the brain in disease states and provide groundwork for translational work in clinical settings. Multiplexing neurochemical measurements in multiple brain regions simultaneously have long been in demand in the greater neuroscience community. Metal microelectrode arrays have been vastly used for neural recordings but cannot measure biomolecules in the brain. Conversely, carbon fiber microelectrodes (CFMEs) have been known to measure neurotransmitters with FSCV due to their ability to adsorb cationic monoamine neurotransmitters on the surface through electrostatics or pi-pi stacking. Although FSCV in tandem with CFMEs have high temporal and spatial resolution, only a single channel potentiostat and electrodes have been utilized. In this work, we configured the carbon fiber multielectrode array (MEA), to a commercially available 4-channel potentiostat for multiplexing neurochemical measurements. The MEA’s relative performance was compared to single channel CFMEs. Dopamine detection was found to be adsorption controlled on the surface of the multielectrode array. Multiple waveforms were applied to each fiber of the multi array simultaneously to detect four different analytes on each electrode of the MEA. A proof of concept ex-vivo experiment showed that the MEA could record redox activity in the mouse caudate putamen and detect dopamine in a 3mm2 area. To our knowledge, this is the first use of the MEA paired with a commercial multichannel potentiostat for multi-waveform application and neurotransmitter codetection. This novel array may aide in future studies to better understand complex brain heterogeneity, the dynamic neurochemical environment, and how disease states or drugs affect separate areas concurrently.