A Hydrogen Peroxide Biosensor Based On Tomato Skin And Oxygen Electrode

A new hydrogen peroxide biosensor, which based on tomato skin and oxygen electrode, has been prepared in this study. The experiment conditions, response behaviors and the shelf-life of the biosensor were studied in detail. And it was supplied to test the hydrogen peroxide content in some commercial samples.The manufacture processes for constructing plant-tissue based biosensors and enzyme-based biosensors are very complicated. There is natural catalase in the tomato skin, the tomato skin is water-resistant and gas-penetrative and can be fixed onto the oxygen electrode directly as the sensor material. So, the tomato skin was used to develop a cheap, simple and sensitive plant-tissue based biosensor due to its special physical and chemical properties.The test mechanism for this biosensor was based on the change of dissolved oxygen level in sample solution. Catalase is a heme-containing enzyme that it ubiquitous in aerobic organisms. It catalyzes the decomposition of hydrogenperoxide to water and oxygen:In this experiment, the tomato skin can provide catalase to decompose the hydrogen peroxide in sample solution with a concomitant increase of dissolved oxygen concentration. A Clark-type oxygen electrode can easily monitor molecular oxygen produced in the enzymatic reaction. Since the enzymatic reaction is the first-order kinetics with respect to the substrate, the amounts of hydrogen peroxide decomposed and oxygen generated will be directly proportional to the concentration of the hydrogen peroxide.The results of the experiments showed that: the detection limit of this hydrogen peroxide biosensor was 30μM, and the response time is less than 100s with a good linear response range of 0.06mM-0.6mM hydrogen peroxide (R~2=0.9998); the concentration of the buffer solution had no obvious effect on the response signal; it had wide temperature and pH working ranges; some common ions didn't cause obvious interference for the biosensor; the shelf-life was more than 6 months; It has been applied to determine the hydrogen peroxide content in some commercial samples, and obtained good analytic results.Therefore, an inexpensive, simple, sensitive hydrogen biosensor was constructed with tomato skin and oxygen electrode, the response time of this biosensor was short, it could determine the hydrogen peroxide content fast and exactly. To our knowledge, this is the first time to fabricate a tissue-biosensor with tomato skin. The development of this hydrogen peroxide biosensor was really helpful for the new biosensor researches, and made the commercial manufacture of this biosensor become possible.