Criteria for Designing a Polypyrrole Glucose Biosensor by Galvanostatic Electropolymerization

Abstract

The polypyrrole (Ppy) glucose biosensor prepared by the galvanostatic electropolymerization of pyrrole monomer in the presence of glucose oxidase (GODx) in a saline solution (pH 7.0) with a platinum electrode is reported. The performances of the biosensor prepared under the different conditions were investigated and compared. The colored-morphology of Ppy/GODx first presented with the optical microscope revealed that the immobilized GODx were over-covered by the polypyrrole which was a serious diffusion barrier of glucose when the pyrrole monomer concentration was higher than 0.075 M. Considering the sensitivity and selectivity, the optimal condition for galvnostatically preparing this biosensor was 0.05 M pyrrole, 0.5 mg/mL GODx, 382 μA/cm2 applied current density, and 50 mC/cm2 film thickness. Finally, the linear range of this optimized glucose biosensor was from zero to 12 mM and the sensitivity of that was 11 nA/mA. The kinetic parameters of Km and Imax for this sensor were 48.8 mM and 628 nA, respectively. The criteria for designing an optimal glucose biosensor by the galvanostatic electropolymerization were obtained.