Preparation Of Silicon Substrate Biochip Technology Research

The development of biosensor and biochip would need the stable electrical communication between biomolecule and substrate. Diamond has been recognized as an ideal substrate due to unusually good properties such as physical stability, chemical inertness, a high thermal conductivity and biocompatibility. The boron doped diamond film exhibits wide potential window and low background current.In the present work, we studied about the mechanism of the formation and the crystalline structure of diamond, described the nature of diamond. The surface of the diamond was chemical modified with oxidization and hydrolysis treatment. The carboxylic group was modified to the surface. And we discussed the effect of a variety of conditions through the infrared spectrum. Direct covalent immobilized the glucose oxidase on carboxylated diamond films with EDC. And verified a long-term stability of the fixed oxidase. Finally, we detected the relationship between the changing of the glucose concentration and the current strength using a three-electrode system.Firstly the diamond film was chemically treated in H2SO4 and HNO3, in which the HNO3 is the oxidated acid and the H2SO4 is the catalyst acid. The oxidized diamond film was successively treated with NaOH and HC1. The FTIR and XPS result showed that the diamond surface was modified with carboxyl through oxidation and hydrolysis. We analysed the absorbance of OH from FTIR, it indicated that under the condition of HNO₃: H₂SO₄ =1: 5, 20h, stir status made the best effect. The variance analysis showed that the ratio of the H₂SO₄ and HNO₃, time and the treatment method were not significantly affect the absorbance. It may be attributed to the oxidation of the diamond surface, which lead to the decrease of the hydrogen.Secondly the GOD were directly covalent immobilized to the carboxylic diamond surface. It was assayed by spectrophotometry. We chose the ABTS as the chromogenic reagent and obtained the activity of the GOD is 0.007U/25mm². Showed that glucose oxidase has been fixed on the diamond film. The long term stability of the GOD was investigated. Finally, as an electrode, diamond film which covered enzyme is more sensitive and accurate than the traditional enzyme electrode. We can use diamond film instead of enzyme film as an electrode for biosensors, and detected the concentration of the glucose with a three-electrode system.