Glucose and choline on-line biosensors based on electropolymerized Meldola's blue

Electropolymerized film of Meldola's blue (MB) was prepared and demonstrate d as electron shuttle between the immobilized horse peroxidase (HRP) and gl assy carbon electrode (GCE) for sensing hydrogen peroxide (H2O2) produced b y enzyme catalytical reactions. Electrochemical polymerization of Meldola's blue was carried out by cyclic voltammetry (CV) in a phosphate buffer solu tion (pH 7.00) in a potential window from - 0.60 to + 1.30 V. The pH of the electropolymerization solution was found to be closely related to the resu lted polymeric MB and the best polymeric film was obtained in a pH 7.00 pho sphate buffer. The polymeric MB was demonstrated to shuttle the electron tr ansfer between the immobilized HRP and GCE and utilized as a mediator for H RP immobilized biosensor for biocatalytical reduction of H2O2 at a potentia l of - 0.30 V (versus AgCl/Ag). The H2O2 sensing system was applied to cons truct glucose and choline on-line sensors by wiring H2O2 produced by enzyme oxidase catalytical reaction. The possibility of these sensors as on-line detectors for on-line and continuous measurement was explored off-line. The operating potential, interference, and lifetime of these sensors were also examined. (C) 2000 Elsevier Science B.V. All rights reserved.