Silica sol-gel immobilized amperometric biosensor for hydrogen peroxide

An amperometric enzyme electrode for hydrogen peroxide was developed via easy and effective enzyme immobilization using the sol-gel technique. The enzyme electrode comprises horseradish peroxidase (HRP) immobilized in the silica sol-gel matrix on a carbon paste electrode (CPE). Hydrogen peroxide was detected in the presence of hexacyanoferrate(II) as a mediator to transfer electrons between the electrode surface and hydrogen peroxide. The effects of operational parameters such as the operating potential of the working electrode, mediator concentration and pH, and thermal stability, were explored for optimum analytical performance by using an amperometric method. Linear calibration for hydrogen peroxide was obtained in the range 2x10(-5) to 2.6x10(-3) M under the optimized conditions. The apparent Michaelis-Menten constant of the enzyme electrode was 4.8 mM. The performance of this enzyme electrode was also investigated using flow-injection analysis. The enzyme electrode retained about 60% of its activity after 35 days of storage in a phosphate buffer at 4 degrees C.