Pedot:Perchlorate Coatings for the Enchancement of Biogenic Amine Detection at Platinum

Abstract

With this study, we describe a method for electropolymerizing a PEDOT:Perchlorate polymer onto the surface of platinum disk microelectrodes. Using cyclic voltammetry as an electropolymerization technique, we deposit an approximately 13 ± 1 µm thick coating of the polymeric material that enhances the electron transfer kinetics of biogenic amines. EDX and spectral imaging showed dense regions of carbon, oxygen, sulfur, and chlorine on the surface of platinum, which verified coating success. Using electrochemical characterization techniques, the apparent capacitance of the PEDOT:Perchlorate coated platinum microelectrodes was 2700 ± 300 µF/cm2. Dopamine, a biologically relevant neurotransmitter of interest had a k0 of 2.7 ± 0.1 x 10-3 cm/s at uncoated platinum and 13 ± 2 x 10-3 cm/s at the PEDOT:Perchlorate coated platinum. Ferrocene carboxylic acid conversely, had a k0 of 3.2 ± 0.3 x 10-3 cm/s at uncoated platinum and 6.1 ± 0.2 x 10-3 cm/s at the PEDOT:Perchlorate coated platinum. Ascorbic acid had a k0 of 30 ± 10 x 10-3 cm/s while serotonin had a k0 of 8.9 ± 0.5 x 10-3 cm/s at the PEDOT:Perchlorate coated platinum. The oxidation and reduction of these molecules was irreversible at bare platinum. In addition to this, the PEDOT:Perchlorate coated platinum microelectrodes were used to perform fast-scan cyclic voltammetry (FSCV) measurements of dopamine and ferrocene carboxylic acid. Scanning at 100 V/s, the PEDOT:Perchlorate coated electrodes exhibited a sensitivity of 1.43 ± 0.03 nA/µM. The PEDOT:Perchlorate coated platinum electrode also lost 34 ± 9 % of its function over the duration of 90 minutes. The ability for modified metal-based (platinum) electrodes to perform FSCV measurements at 100 V/s creates a new sensing platform for evaluating the underlying mechanisms that govern volume neurotransmission between different brain regions real time during behavior.