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    ABSTRACT: An amperometric biosensor based on horseradish peroxidase (HRP) and γ-Al2O3/chitosan composite film at a glassy carbon electrode has been developed. Hydrogen peroxide (H2O2) 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 (2O2 with the detection limit of 0.07 μM. The linear response range of the enzyme electrode to H2O2 concentration was from 0.5 to 700 μM 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 H2O2.
    Full-text · Article · Mar 2011 · Journal of Solid State Electrochemistry