Electrochemical Detection of Adrenaline and Hydrogen Peroxide on Carbon Nanotube Electrodes

Abstract

Adrenaline and hydrogen peroxide have neuromodulatory functions in the brain. Considerable interest exists in developing electrochemical sensors that can detect their levels in vivo due to their important biochemical roles. Challenges associated with electrochemical detection of hydrogen peroxide and adrenaline are that the oxidation of these molecules usually requires highly oxidising potentials (beyond 1.4 V vs Ag/AgCl) where electrode damage and biofouling are likely and the signals of adrenaline, hydrogen peroide and adenosine overlap. To address these issues we fabricated pyrolysed carbon electrodes coated with oxidised carbon nanotubes (CNTs). Using these electrodes for fast-scan cyclic voltammetric (FSCV) measurements showed that the electrode offers reduced overpotentials compared with graphite and improved resistance to biofouling. The Adrenaline peak is reached at 0.75({+/-}0.1) V and reduced back at -0.2({+/-}0.1) V while hydrogen peroxide is detected at 0.85({+/-}0.1) V on this electrode. The electrodes are highly sensitive with a sensitivity of 16nA {micro}M-1 for Adrenaline and 11nA {micro}M-1 for hydrogen peroxide on an 80 {micro}m2 electrode. They are also suitable to distinguish between adrenaline, hydrogen peroxide and adenosine thus these probes can be used for multimodal detection of analytes.