Abstract:

A modified electrode was developed by immobilizing horseradish peroxidase(HRP) onto a biocompatible glassy carbon electrode(GCE) modified with a DNA/poly(ferrocenylsilane)(PFS)/room temperature ionic liquid(RTIL) film and the asprepared GCE/DNA/PFS/RTIL/HRP electrode provides both a biocompatible microenvironment for HRP to keep its good bioactivity and an effective pathway of electron transfer between the redox center of HRP and the electrode surface. The modified electrode showed a good electrocatalytic behavior toward the reduction of H2O2. The electrocatalytic behaviors of GCE/DNA/PFS/RTIL/HRP to the reduction of H2O2 were investigated by cyclic voltammograms and amperometric technique in detail. Under the optimized conditions, the modified electrode shows fast response to the electrocatalytic oxidation of H2O2 and the steady current was observed within 2 s. The catalytic current is linear to the H2O2 concentration in the range of 3.25 μmol/L to 1.47 mmol/L and 1.86 mmol/L to 5.35 mmol/L. The detection limit was 0.86 μmol/L based on the criterion of a signal-to-noise ratio of 3. The biosensor showed high sensitivity, good reproducibility and stability. Furthermore, the modified electrode also showed a good electrocatalytic behavior toward the reduction of O2.

Key words: DNA, horseradish peroxidase, hydrogen peroxide, ploy(ferrocenylsilane), room temperature ionic liquid