Electrospun biocatalytic hybrid silica–PVA-tyrosinase fiber mats for electrochemical detection of phenols

Abstract

Electrospinning and sol–gel chemistry have been combined to fabricate a fibrous electrode material of silica–PVA with immobilized tyrosinase enzyme onto an indium–tin oxide (ITO)-coated glass substrate to detect phenolic compounds, or more directly quinones that are catalytically generated from catechol, phenol, and p-cresol. The effect of fiber mat (silica–PVA or silica–PVA-tyrosinase) thickness on the electrochemical performance of the electrode has been studied with cyclic voltammetry and linear polarization resistance, indicating that electron transfer from or through thicker mats is hindered. Mats thinner than 10μm have the advantages of faster electrospinning fabrication, higher current densities (lower polarization resistance), and minimized electrode contamination from surface adsorption during use. The performance of the working electrodes toward sensitivity and response time has also been studied with cyclic voltammetry and chronoamperometry. Sensitivity to phenolic concentrations were found to follow the trend of catechol>phenol>p-cresol, with approximately 10μM as a practical limit of detection and linear operating behavior up to 100mM. Electrode operating lifetime was drastically reduced under repeated contact with high concentrations that also showed significant fouling.