A novel hydrogen peroxide biosensor based on horseradish peroxidase immobilized on gold nanoparticles–silk fibroin modified glassy carbon electrode and direct electrochemistry of horseradish peroxidase

The preparation of horseradish peroxidase (HRP)–gold nanoparticles (AuNPs)–silk fibroin (SF) modified glassy carbon electrode (GCE) by one step procedure was reported for the first time. The direct electrochemistry of HRP at the modified electrode was investigated. The enzyme electrode showed a quasi-reversible electrochemical redox behavior with a formal potential of −210 mV (vs. SCE) in 0.1 M phosphate buffer solution at pH 7.1. The response of the biosensor showed a surface-controlled electrochemical process with one electron transfer accompanying with one proton. The cathodic transfer coefficient was 0.42, the electron transfer rate constant was 1.84 s−1 and the surface coverage of HRP was 1.8 × 10−9 mol cm−2. The experimental results indicated that AuNPs–SF composite matrix could not only steadily immobilize HRP, but also efficiently retain its bioactivity. The biosensor displayed an excellent and quick electrocatalytic response to the reduction of H2O2.