Porous-Magnetic Chitosan Microsphere/Horseradish Peroxidase Modified Electrode for the Selective Determination of Hydrogen Peroxide

A porous-magnetic chitosan microsphere was prepared for the electrode modification and immobilization of horseradish peroxidase (HRP), which could be used for the selective determination of hydrogen peroxide (H2O2). Transmission electron microscope was used to characterize the structure of the porous microsphere, and electrochemical impedance spectroscopy, cyclic voltammetry and steady-state amperometry were used to study the electrochemical behavior of this modified electrode and its catalytic response towards H2O2. The effects of HRP concentration, pH and working potential on the biosensing responses were optimized. Under the optimum experimental conditions, this biosensor showed a fast catalytic response towards H2O2 less than 10 s, and a wide linear range from 0.49 mu M to 0.20 mM and a detection limit of 0.27 mu M were obtained. In addition, the biosensor had good selectivity, sensitivity and reproducibility, thus indicating great potential for H2O2 determination in practical samples.