Dendritic silver/silicon dioxide nanocomposite modified electrodes for electrochemical sensing of hydrogen peroxide

A novel biosensor for hydrogen peroxide was prepared by immobilizing horseradish peroxidase (HPR) on newly synthesized dendritic silver/silicon dioxide nanocomposites, which were coated on a glassy carbon electrode. The modified electrode was characterized with XPS, SEM, and electrochemical methods. This biosensor showed a very fast amperometric response to hydrogen peroxide with a linear range from 0.7 to 120 mu M, a limit of detection of 0.05 mu M and a sensitivity of 1.02 mA mM(-1) cm(-2). The Michaelis-Menten constant of the immobilized HRP was estimated to be 0.21 mM, indicating a high affinity of the HRP to H2O2 without loss of enzymatic activity. The preparation of the proposed biosensor was convenient, and it showed high sensitivity and good stability.