Glucose and choline on-line biosensors based on electropolymerized Meldolaʹs blue

Electropolymerized film of Meldolaʹs blue (MB) was prepared and demonstrated as electron shuttle between the immobilized horse peroxidase (HRP) and glassy carbon electrode (GCE) for sensing hydrogen peroxide (H2O2) produced by enzyme catalytical reactions. Electrochemical polymerization of Meldolaʹs blue was carried out by cyclic voltammetry (CV) in a phosphate buffer solution (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 resulted polymeric MB and the best polymeric film was obtained in a pH 7.00 phosphate buffer. The polymeric MB was demonstrated to shuttle the electron transfer between the immobilized HRP and GCE and utilized as a mediator for HRP immobilized biosensor for biocatalytical reduction of H2O2 at a potential of −0.30 V (versus AgCl/Ag). The H2O2 sensing system was applied to construct 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.