Conductive Polymer-Graphene Oxide Composite Fibers as High-Performance Microelectrodes for Dopamine Sensing

Carbon fiber microelectrodes have been used for the detection of neurochemicals due to their wide potential window, functional groups for adequate adsorption and biocompatibility. Researchers primarily concentrate on coating carbon fiber microelectrodes with diverse materials to improve sensitivity, selectivity and detection limits: however little research has been done on alternative fiber composites that provide better tunability and functionalization. Carbon nanotube yarn electrodes have been tested as novel material for neurochemical detection, yet widespread adoption has been limited due to necessity of having expensive reactors or access to state-of-the-art carbon synthesis equipment. Here, we report the fabrication of novel composite fibers made of polyethylene dioxy thiophene, polystyrene (PEDOT: PSS) and graphene oxide by a hydrothermal method. The average diameter is between 20-30μm. This approach to synthesizing composite materials is easily adaptable in a variety of lab environments due to the limited need for expensive equipment. We optimized various ratios (1:6, 1:9, 1:12) of PEDOT: PSS and GO and used fast-scan cyclic voltammetry (FSCV) for material characterization. Among the ratios tested, 1:9 PEDOT: PSS/GO hybrid fiber had an electroactive surface area of (5- fold) compared to GO fibers. These composite fibers were sensitive (4-fold) had lower detection thresholds, and had increased surface coverage for dopamine adsorption as compared to GO fibers alone. Synergistic interplay between the conductive PEDOT backbone, negatively charged PSS and GO promote electron transfer and attraction to positively charged analytes such as dopamine to the surface. These findings suggest that PEDOT: PSS/GO fiber electrodes are a promising alternative to carbon fibers for real-time monitoring of neurochemical sensing.