A novel hydrogen peroxide sensor based on the direct electron transfer of horseradish peroxidase immobilized on silica–hydroxyapatite hybrid film

The direct electron transfer of immobilized horseradish peroxidase (HRP) on silica–hydroxyapatite (HAp) hybrid film-modified glassy carbon electrode (GCE) and its application as H2O2 biosensors were investigated. On silica/HRP–HAp/GCE, HRP displayed a fast electron transfer process accompanied with one proton participate in. This sensor exhibited an excellent electrocatalytic response to the reduction of H2O2 without the aid of an electron mediator. The proposed biosensor showed good reproducibility and high sensitivity to H2O2 with the detection limit of 0.35 μM. In the range of 1.0–100 μM, the catalytic reduction current of H2O2 was proportional to H2O2 concentration. The apparent Michaelis–Menten constant (kmapp) of the biosensor was calculated to be 21.8 μM, exhibiting a high enzymatic activity and affinity for H2O2.