A one-step method to construct a third-generation biosensor based on horseradish peroxidase and gold nanoparticles embedded in silica sol-gel network on gold modified electrode

A one-step method for fabrication of horseradish peroxidase (HRP) biosensor has been developed. The gold nanoparticles and HRP were simultaneously embedded in silica sol-gel network on gold electrode surface in the presence of cysteine. The immobilized HRP exhibited direct electrochemical behavior toward the reduction of hydrogen peroxide. The heterogeneous electron transfer rate constant was evaluated to be 7.8 s−1. The biosensor displayed an excellent elctrocatalytic response to the reduction of H2O2 without any mediator. The calibration range of H2O2 was from 1.6 μmol L−1 to 3.2 mmol L−1 and a detection limit of 0.5 μmol L−1 at a signal-to-noise ratio of 3. The KMapp value of HRP immobilized on the electrode surface was found to be 1.1 mmol L−1. The biosensor exhibited high sensitivity, rapid response and long-term stability.