Electropolymerization of preoxidized catecholamines on Prussian blue matrix to immobilize glucose oxidase for sensitive amperometric biosensing

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 mu A mM(-1) cm(-2) and a limit of detection of 0.3 mu M 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 Cox retained high enzymatic specific activity, as quantified by UV-vis spectrophotometry and EQCM. L-Noradrenalin 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. (C) 2008 Elsevier B.V. All rights reserved.