Electrochemical study on effect of colloidal Au on horseradish peroxidase in polypyrrole layer at prussian blue modified electrode

Abstract

Cyclic voltammetry and current-time curve have been used to investigate the Au-colloid function on the horseradish peroxidase biosensor response. Firstly Prussian blue is deposited on the electrode, and then the polypyrrole (PPY)/HRP biosensor is constructed by electrochemical oxidization of pyrrole in the solution containing horseradish peroxidase and pyrrole. The colloidal Au is then immobilized on the electrode. Cyclic voltammograms show higher current in the presence of Au-colloid as compared to that in the absence of the colloid. The PB/PPY/HRP and PB/PPY/HRP/Au-colloid biosensors exhibit linear current-time response to hydrogen peroxide over a concentration range of 2χ10⁻⁶ M – 1.8χ10⁻⁴ M. Michaelis-Menten constants of the two biosensors are 0.63 and 0.35 mM, respectively. The dependence of current responses on applied voltage has been discussed and the mechanism has been proposed. The results show that colloidal Au enhances the current response and decreases the energy barrier of electron transfer reaction on the electrode. The interference of foreign substances has also discussed.