Electrochemical characterization of an enzyme electrode based on a ferrocene-containing redox polymer

Abstract

The electrochemical characterization of an enzyme electrode based on a ferrocene-containing redox polymer is described. A redox polymer based on cross-linked polyallylamine with covalently attached ferrocene was prepared. Glucose oxidase (GOx) and this redox polymer were cross-linked using glutaraldehyde and bovine serum albumin (BSA) on a glassy carbon electrode surface. The BSA-based immobilization was highly effective to stabilize the electrochemical response of the redox polymer. The electrochemical behavior of the redox polymer was found to be almost completely based on a semi-infinite diffusion process except for a small amount of the redox polymer-enzyme loading. The effect of pH was examined over the pH range from 2.2 to 11 without substrate. The anodic peak current increased with increase in pH value in the range above 8. The redox potential was shifted positively as the pH value decreased in the range below 6. The catalytic electrochemistry of the enzyme electrode with the redox polymer was investigated. The enzyme electrode loaded at high redox polymer and high enzyme content showed a prepeak at low glucose concentration in cyclic voltammograms. A prepeak was also observed at high enzyme-polymer loading. A steady state response to glucose was also measured. The enzyme electrode with the redox polymer was able to determine glucose concentrations up to 7 mM.