Sol-gel thin-film immobilized soybean peroxidase biosensor for the amperometric determination of hydrogen peroxide in acid medium

An acid-stable soybean-peroxidase biosensor was devel oped by immobilizing the enzyme in a sol-gel thin film. Methylene blue was used as a mediator be cause of its high electron-transfer efficiency. The sol-gel thin film and e nzyme membrane were characterized by FT-IR, and the effects of pH, operatin g potential, and temperature were explored for optimum analytical performan ce by using the amperometric method. The H2O2 sensor exhibited a fast respo nse (5 s), high sensitivity (27.5 mu A/mM), as well as good thermostability and long-term stability. In addition, the performance of the biosensor was investigated using flow-injection analysis (FIA).