Amperometric Hydrogen Peroxide Biosensor Based on Horseradish Peroxidase Immobilized on Fe3O4/Chitosan Modified Glassy Carbon Electrode

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Abstract
A new type of amperometric hydrogen peroxide biosensor was constructed based on horseradish peroxidase (HRP) immobilized on Fe3O4/chitosan modified glassy carbon electrode. The effects of some experimental variables such as the concentration of supporting electrolyte, pH, enzyme loading, the concentration of the mediator of methylene blue (MB) and the applied potential were investigated. The linear range of the calibration curve for H2O2 was 2.0×10−4–1.2×10−2 M with a detection limit of 1.0×10−4 M (S/N=3). The response time was less than 12 s. The apparent Michaelis‐Menten constant Km was 21.4 mM and it illustrated the excellent biological activity of the fixed enzyme. In addition, the biosensor had long‐time stability and good reproducibility. And this method has been used to determine H2O2 concentration in the real sample.