Enzyme Immobilized On The New Nano-structure Of Tio <sub> 2 </ Sub> Thin Film Electrode And Its Biological Electrochemical Performance

The development of nano-techonology provides a new opportunity to the development of biosensors. Nanobiosening technology is revealing its superiority not only have good effect on it, but also on biosensor. This dissertation focuses on 1) fabricating novel biosensors based on new nanomaterials and nanostructures, and integrated them with microdialysis, flow injection analysis, etc. 2) establishing the bases for application of them to detect glucose, hypoxanthine and organophosphate pesticides. We are adhering to an organic combination of nanotechnology, biosensing technology and clinical researches. The details are given as follows:SiO₂-TiO₂ composite nanoparticles have been synthesized by utilizing TiO₂ nanopartilces obtained by a sol-gel method, followed by an impregnation process with Ag+, Pt+ and Ru3+ solution. The results of sterilization show that, the bactericidal effect of TiO₂ nanoparticles modified by Pt is stronger than that of TiO₂ nanoparticles, appreciably; The bactericidal effect of TiO₂ nanoparticles modified by Ru is lower than that of TiO₂ nanoparticles; The bactericidal effect of TiO₂ nanoparticles modified by Ag is obviously stronger than that of TiO₂ nanoparticles, especially under visible light, extending the application of TiO₂ nanoparticles.SiO₂-TiO₂ composite nanoparticles have been synthesized by utilizing TiO₂ nanopartilces obtained by a sol-gel method, followed by an impregnation process with SiO₂ sol. The effects of the SiO₂ on the thermal stability and photocatalytic activity of anatase nanoparticles were mainly investigated. The results show that the SiO₂ can greatly enhance the thermal stability, even having a principal anatase phase composition after thermal treatment at 900℃. During the processes of photocatalytic degradation RhB, all the as-prepared SiO₂-TiO₂ composite nanoparticles by thermal treatment at high temperature exhibit higher activity than P-25 TiO₂, which is attributed to their high anatase crystallinity and to their large surface area.Gold nanoparticles-modified SiO₂-TiO₂ nanocomposite (Au/SiO₂-TiO₂) was used to immobilize horseradish peroxidase (HRP) on a glassy carbon electrode surface for the construction of an amperometric hydrogen peroxide (H2O2) biosensor. The properties of HRP immobilized in the Au/SiO₂-TiO₂ film were characterized by the electrochemical methods. the HRP immobilized in Au/SiO₂-TiO₂/GC electrode exhibited a rapid electrocatalytical response. The good direct electrochemical behavior of HRP and electrocatalytical response to H2O2 reduction was due to the enhancement of specific surface area and the reduction of electron transfer resistance by the uniform deposition of gold nanoparticle on SiO₂-TiO₂ surface.