Determination of hydrogen peroxide using a biosensor based on Fe3O4 magnetic nanoparticles and horseradish peroxidase with graphene-chitosan composite

A novel hydrogen peroxide (H₂O₂) biosensor was constructed based on Fe₃O₄ magnetic nanoparticles (MNPs) and horseradish peroxidase with graphene-chitosan composite material as a matrix. Fe₃O₄ MNPs were synthesised by chemical co-precipitation with sodium citrate as surfactant. Fourier transform infrared spectroscopy and transmission electron microscopy were applied for the characterisation of the obtained Fe₃O₄ MNPs. The conductivity of different composite films was researched by electrochemical impedance spectroscopy and the electrocatalytic properties of the H₂O₂ biosensor were studied by cyclic voltammetry. Under optimal conditions, experimental results indicated that the biosensor could electrocatalyse the reduction of H₂O₂; the reduction peak current had a good linear relationship with the concentration of H₂O₂ from 2.49 × 10^-5 to 1.67 × 10^-3 mol/l (R = 0.9990). The detection limit was 3.05 × 10^-6 mol/l (S/N = 3). This novel biosensor showed good sensitivity, stability and repeatability for H₂O₂ detection.