Characterization of a 32 μm diameter carbon fiber electrode for in vivo fast-scan cyclic voltammetry

Abstract

Carbon fiber electrodes (CFE) are commonly used for in vivo detection of catecholamines due to their excellent electrochemical properties and biocompatibility. Fast-scan cyclic voltammetry (FSCV) combined with CFEs permits the detection of catecholamines such as dopamine (DA) with high specificity and reliability. However, advances in neuroscience constantly demand sensors with greater sensitivities and selectivities. This study investigated an untreated CFE of 32μm diameter and 300μm exposed length for detection of DA using FSCV. Despite the larger area of the working electrode, we observed only a small increase in the background current in comparison with the commonly used CFE of 7μm diameter and 100μm exposed length. The sensitivity of the 32μm CFE was 9 times greater than that of the 7μm CFE. These larger electrodes exhibited good linearity and a 6 fold higher signal-to-noise ratio than 7μm CFEs in vitro. The 32μm CFE showed significantly better selectivity for DA in preference to 3,4-dihydroxyphenylacetic acid than the 7μm CFE and similar selectivity to the 7μm CFE for ascorbic and homovanillic acid. The electrodes displayed good temporal resolution and electrochemical stability in both in vitro and in vivo tests.