Electropolymerization of preoxidized catecholamines on Prussian blue matrix to immobilize glucose oxidase for...

We examine here the electropolymerization of electrochemically or chemically preoxidized catecholamines in glucose oxidase (GOx)-containing neutral solutions to efficiently immobilize the enzyme at Prussian blue-modified Au electrodes for sensitive amperometric biosensing of glucose. The electrochemical quartz crystal microbalance (EQCM) was used to track various electrode-modification processes. The optimized poly(dopamine)-based glucose biosensor displayed a sensitivity of 35 microA mM(-1) cm(-2) and a limit of detection of 0.3 microM at 0.7 V vs. SCE, and similar results were obtained at -0.05 V vs. SCE, which are obviously better than those from preoxidation-free conventional electropolymerization. The immobilized GOx retained high enzymatic specific activity, as quantified by UV-vis spectrophotometry and EQCM. L-noradrenaline could similarly electropolymerize and the resultant enzyme film gave equivalent biosensing characteristics, but the electropolymerization of EP was less efficient and the resultant enzyme film showed notably poorer performance.