Development of a sol-gel based amperometric biosensor for the determination of phenolics

Sol-gel coated horseradish peroxidase (HRP) electrodes were constructed by complexing HRP with the redox osmium polymer [Os(bpy)(2)(PVP)(10)Cl]Cl on a glassy carbon electrode. Kinetic studies for the biosensor optimisation using hydrogen peroxide and cumene hydroperoxide as substrates were performed in both phosphate buffer and acetonitrile media using cyclic voltammetric and steady state amperometric modes, under anaerobic conditions. The apparent turnover rate constants (k'(cat)), apparent Michaelis-Menten constant (K'(M)) and substrate specificity factor (k'(cat)/K'(M)) were evaluated and discussed. Results are displayed for the determination of phenols in both aqueous and organic phase systems. The biosensor exhibited a low operating potential, i.e., (0 V versus Ag/AgCl), fast response times, high sensitivity and micromolar detection limits for a range of selected phenols.