Hydrogen peroxide biosensor based on the immobilization of horseradish peroxidase on γ-Al2O3 nanoparticles/chitosan film-modified electrode

An amperometric biosensor based on horseradish peroxidase (HRP) and gamma-Al(2)O(3)/chitosan composite film at a glassy carbon electrode has been developed. Hydrogen peroxide (H(2)O(2)) was detected with the aid of ferrocene monocarboxylic acid mediator to transfer electrons between the electrode and HRP. The morphology and composition of the modified electrode were characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The electrochemical characteristics of the biosensor were studied by cyclic voltammetry and amperometry. The effects of HRP concentration, the applied potential, and the pH values of the buffer solution on the response of the sensor were investigated for optimum analytical performance. The proposed biosensor showed high sensitivity (0.249 A M(-1) cm(-2)) and a fast response (< 5 s) to H(2)O(2) with the detection limit of 0.07 mu M. The linear response range of the enzyme electrode to H(2)O(2) concentration was from 0.5 to 700 mu M with a correlation coefficient of 0.9998. The apparent Michaelis-Menten constant of the biosensor was calculated to be 0.818 mM, exhibiting a high enzymatic activity and affinity for H(2)O(2).