Comparison of electrode materials for the detection of rapid hydrogen peroxide fluctuations using background-subtracted fast scan cyclic voltammetry

Abstract

Hydrogen peroxide (H₂O₂) is a critically important signaling molecule. Endogenous H₂O₂ mediates diverse physiological processes both intra- and intercellularly; and enzymatically generated H₂O₂ is a widely used reporter molecule at biosensors that rely on enzymes to detect non-electroactive species. However, the development and application of electroanalytical methods for the direct detection of this molecule has been challenging because the electron transfer kinetics for the irreversible oxidation of H₂O₂ are slow. We comparatively characterize the electrochemical oxidation of H₂O₂ on bare and Nafion^®-coated platinum and carbon-fiber microdisc electrodes using fast-scan cyclic voltammetry (FSCV). Using a waveform ranging from +0.2 to +1.3 V at 400 V s⁻¹, the electrocatalytic properties of the platinum surface were not readily apparent, and the carbon-fiber microelectrode demonstrated greater sensitivity and selectivity toward H₂O₂. Nafion^®-coating further enhanced detection on carbon electrodes. These results confirm that platinum electrodes, with or without Nafion^®, will not work acceptably with this approach, and confirm the value of carbon-fiber microelectrodes relative to more traditionally used platinum electrodes in the direct detection of rapid H₂O₂ fluctuations using FSCV.