Studies Of The Third-Generation Electrochemical Biosensors Based On The Inorganic Nanosheets

Much attention has been devoted to the development of the third-generation electrochemical biosensor based on direct electrochemistry of enzymes, and nanomaterials provide a new way to construct the third-generation biosensor. Nanosheets, a novel class of nanoscale materials, possess anisotropic morphology, polyelectrolytic and colloidal nature. It is significative that nanosheets are used to improve the direct electrochemistry between enzymes and electrodes.In this thesis, the nanosheets (zirconium phosphate nanosheets, layered double hydroxide nanosheets and titania nanosheets) were used to immobilize myoglobin (Mb) or glucose oxidase (GOD) and investigate the electrochemical properties. The main contents of the thesis are given as follows:1. Zirconium phosphate nanosheets (ZrPNS) were firstly applied to the immobilization of Mb as a support matrix. Mb almost retained bioactivity in the film. In ZrPNS film on the glassy carbon electrode, Mb realized its direct electrochemistry and displayed good thermal stability. The catalytic abilities of the protein toward the reduction of H₂O₂, O₂, NaNO₂ and trichloroacetic acid were also studied and a third-generation biosensor was subsequently fabricated. The biosensor also exhibited acceptable anti-interferant ability, reproducibility and stability.2. Layered double hydroxide nanosheets (LDHNS) were firstly applied to the immobilization of GOD as a support matrix. GOD almost retained bioactivity in the film. The electrochemical results revealed that LDHNS could improve greatly the direct electrochemistry of GOD, while layered double hydroxide nanoparticles (LDHNP) can only achieve the direct electrochemistry of GOD in a very small extent. 3. Titania nanosheets (TNS) were applied to the immobilization of Mb via layer-by-layer (LBL) technology. Mb retained good bioactivity in the LBL film and realized effective direct electrochemistry behavior. The biosensor displayed high catalytic efficiency towards O₂ and H₂O₂, and possessed good reproducibility and stability.