The Study Of The Electrochemical Biosensor Based On Ordered Porous Nanocomposites-Pt/TiO₂, Au@TiO₂

Nanoporous materials, contain a lot of closed or connected hollows, always possess high specific surface areas and rich pore channels. Hierarchical nanoporous materials can have a range of pores with different pore sizes, not only have the advantages of single aperture material, but also overcome the limitations of single aperture at the same time, which make their application more widely. There are many preparation methods of hierarchical nanoporous materials, such as hard template method, soft template method and biotemplate method. Biomaterials are widely exist in the nature, biotemplates are biometerials which have unique hierarchical structures, and can be used as the template to prepare nanomaterials with hierarchical structures and special morphologies.Hierarchical nanoporous materials are widely used in electrochemical sensors because of their unique properties. In electrochemical enzyme biosensors, hierarchical nanoporous materials are often used to load enzymes due to their good stability, biocompatibility, and large surface area. They can maintain the enzyme activity, and a large amount of enzyme molecules can be directly adsorbed and fixed to the electrode surface to let the electrons transmit directly between redox-active centers and electrode surface, to solve the problem of inefficient communication between the enzyme and the electrode. In non-enzymatic electrochemical sensors, hierarchical nanoporous materials are used to load active material, for a large specific surface area can improve the mass loading of active material and the rich porous channels may facilitate the direct contact of substrate and active materials, to increase the effective utilization of active materials and improve the catalytic performance of the electrochemical sensor. In this paper, hierarchical macro/mesoporous anatase TiO2 nanomaterial was successfully prepared with biotemplate method, and was successfully applied in the electrochemical enzyme biosensor and non-enzymatic sensor by combining with Pt and Au nanoparticles, respectively, and with very good results. The specific contents are as follows:1. Hierarchical nanoporous TiO2 were successfully synthesized through double template method by using fresh rose petals and P123 as the template and tetrabutyl titanate as the precursor, with the preparation processes of Czochralski, drying, heat setting and annealing. Characterizations showed that the obtained TiO2 nanomaterial has a highly ordered macro/mesoporous structure with a high specific surface area. Through dip coating and electrodeposition methods, the prepared TiO2 and Pt nanoparticles were successfully fabricated on the glassy carbon electrode (GCE), and after cultivating in horseradish peroxidase (HRP) solution for 12 h, the HRP/Pt/TiO2/GCE modified electrode was obtained. The high specific surface area of TiO2 can greatly improve the adhesion amount of HRP, and the Pt nanoparticles can highly enhance the electrical conductivity of the electrode. After a series of electrochemical characterization of the modified electrode, its catalytic ability to H2O2 was further studied, and a good linear range of 5-8000 μ mol L-1 was obtained with a low detection limit of 1.65μ mol L-1.2. The prepared hierarchical nanoporous TiO2 was dispersed in deionized water and by using chloroauric acid as the precursor, NaBH4 as reducing agent and sodium citrate as stabilizer, Au nanoparticles was successfully loaded on the surface of TiO2 to obtain the Au@TiO2 nanocomposites. The composite material was dip coated on the surface of GCE and then covered with Nafion membrane to fabricate the Nafion/Au@TiO2/GCE electrode. The hierarchical nanoporous TiO2 with high specific surface area can increase the loading mass of Au nanoparticles, and the hierarchical nanoporous structure can effectively inhibit the aggregation of Au nanoparticles to reduce the Au nanoparticles size to enhance the electrical conductivity of the composite material and improve the catalytic ability of H2O2. The electrochemical properties of Nafion/Au@TiO2/GCE showed that the composite material has a good catalytic ability to H2O2 with the linear range of 0.01-12.96 m mol L-1 and detection limit of 5.8 μ mol L-1, as well as good stability and anti-interference ability.