Work

Pyrolyzed Parylene-N for in Vivo Electrochemical Detection of Neurotransmitters

Year: 2025

Type: article

Abstract: Carbon electrodes are typically used for in vivo dopamine detection, and methods to customize fabrication for new applications are being explored. Parylene is an insulator that can be deposited in a thin layer on a substrate, and then pyrolyzed to carbon to enable its use as an electrode. However, pyrolyzed parylene has not been used for the characterization of neurochemicals with fast-scan cyclic voltammetry, which can provide real-time detection and high temporal resolution. In this work, we deposit thin layers of parylene-N (PN) on metal wires, and then pyrolyzed to carbon with high temperatures in a rapid thermal processor (RTP). Different masses of PN, 1 g, 6 g, and 12 g, were deposited to vary the thickness and all of them generated nanoscale layer graphite. RTP-PN (6 g) produced 650 nm layer carbon thicknesses and the best electrochemical performance. Pyrolyzed parylene N modified electrodes (PPNMEs) were characterized for electrochemical detection of dopamine, epinephrine, serotonin, norepinephrine, ascorbic acid and adenosine. Currents at PPNMEs were about 2-4 times larger than carbon-fiber microelectrodes (CFMEs). Rich defect sites and oxygen functional groups promoted neurochemical adsorption for cationic neurotransmitters. PPNMEs resisted fouling from serotonin polymer formation and biofouling from proteins. They were used in vivo to detect stimulated dopamine release and monitor spontaneous adenosine release. Pyrolyzed parylene is a sensitive, fouling-resistant thin film carbon electrode that could be used in the future for making customized devices and geometries.

Source: ACS electrochemistry.

DOI: 10.1021/acselectrochem.4c00180