Enhanced dopamine detection sensitivity by PEDOT/graphene oxide coating on in vivo carbon fiber electrodes
By Taylor, I. Mitch; Robbins, Elaine M.; Catt, Kasey A.; Cody, Patrick A.; Happe, Cassandra L.; Cui, Xinyan Tracy
Published in Biosensors and Bioelectronics
2017
Abstract
Abstract Dopamine (DA) is a monoamine neurotransmitter responsible for regulating a variety of vital life functions. In vivo detection of {DA} poses a challenge due to the low concentration and high speed of physiological signaling. Fast scan cyclic voltammetry at carbon fiber microelectrodes (CFEs) is an effective method to monitor real-time in vivo {DA} signaling, however the sensitivity is somewhat limited. Electrodeposition of poly(3,4-ethylene dioxythiophene) (PEDOT)/graphene oxide (GO) onto the {CFE} surface is shown to increase the sensitivity and lower the limit of detection for {DA} compared to bare CFEs. Thicker PEDOT/GO coatings demonstrate higher sensitivities for DA, but display the negative drawback of slow adsorption and electron transfer kinetics. The moderate thickness resulting from 25 s electrodeposition of PEDOT/GO produces the optimal electrode, exhibiting an 880% increase in sensitivity, a 50% decrease in limit of detection and minimally altered electrode kinetics. PEDOT/GO coated electrodes rapidly and robustly detect DA, both in solution and in the rat dorsal striatum. This increase in {DA} sensitivity is likely due to increasing the electrode surface area with a PEDOT/GO coating and improved adsorption of DA's oxidation product (DA-o-quinone). Increasing {DA} sensitivity without compromising electrode kinetics is expected to significantly improve our understanding of the {DA} function in vivo.