Hydrogen Peroxide Biosensors Based on the Immobilization of Hemoglobin on Amino-Silane Magnetic Nanoparticle-Contained Carbon Paste Electrodes

Amino-silane magnetic nanoparticles (A-SMNPs) were mixed with graphite powder to construct A-SMNPs-contained carbon paste electrodes (CPE). Hemoglobin (Hb) was then immobilized on the electrode surface to form Hb/A-SMNPs/CPE biosensors. The biosensor was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The results indicated that Hb was stably immobilized on the electrode and exhibit excellent electrocatalytic activity to the reduction of hydrogen peroxide without the aid of an electron mediator. When used for amperometric measurement of H₂O₂, the prepared biosensor displayed good sensitivity, selectivity and stability. A linear detection range of H₂O₂ from 1.0 mol L^–1 to 2.0 mmol L^–1 and a detection limit of 0.27 mol L^–1 (S/N = 3) was obtained. The apparent Michaelis-Menten constant was calculated to be 0.85 mmol L^–1, indicating that the immobilized Hb had high enzymatic activity to H₂O₂.