Based On The Titanium Dioxide Nanotubes Signal Enhanced Electrochemical Sensor Research

Biosensor is a frontier and newly-interdisciplinary discipline, involving chemistry, biology, medicine, physics, electronics, which has broad application prospects in the fields of clinical medicine, agricultural production and enviromental protection. In recent years, the rapid development of nanotechnology makes the development of biological sensors, and the new field exploring the application of the nanomaterials in biological sensor was produced. Compared to the traditional biological sensors, the electrochemical biosensors using nanomaterials have higher sensitivity and more advantages. In this study, on the basis of reviewing the nano-materials and biosensors, TiO2nanotube arrays and Au nanoparticles were prepared and applied in the preparation of the novel electrochemical biosensors. The details are given as follows:In the first chapter, we decribed the concept and the recent development and application of the electrochemical biosensors and nano material, and introduced the principle of electrochemical biosensor and immobilized technology of biological molecules, in the last, the application of the nanometer technology in electrochemical biosensors was given. With the application of nanotechnology and nanomaterials in biobiological sensors, the chemical and physical properties were improved, detection sensitivities were greatly enhanced, and detection time was shortened. In the end, we gave a short introduction for the contant and significance of this thesis.The second chapter mainly researched the TiO2Nano-test-tubes as a versatile signal-amplified platform for electrochemical immunoarray, and is applied to the simulation analysis and common clinical immune monitoring things--antigen detection. First, The immune molecules were combined on the annealed TiO2nanotube arrays surface. Simultaneously, by the incorporation of Au colloids to bind horse radish peroxidase (HRP) labelled antibodies as recognition elements, the resultant nanotubular hybrids show high amplified electrochemical signals from the catalytic reaction of the carried HRP relative to H2O2in the solution. In this study, the performance of the electrochemical immunosensor based on TiO2nanotube arrays was examined by cyclic voltammetry method and chronoamperometry. The results showed that due to the high enhanced real surface area of the TiO2nanotubes, the amount of captured analyte on titania nanotube is larger than the flat surface based electrod.Additionally, high amplified electrochemical signals from the catalytic reaction of the carried HRP relative to H2O2in the solution was obtained. Under optimal conditions, the proposed immunosensor exhibited a good electrochemical behavior to antigen in a concentration range from100pg/mL to100μg/mL with a detection limit of10pg/mL. Moreover, the selectivity and stability of the immunosensor were acceptable.In the third chapter, TiO2nanotube arrays are combined with Au nanoparticles to construct AuNPs/TiO2nanotube electrode. The new electrode interface provides an ideal platform for the immobilization and electron transfer of biomolecules. Vertically aligned TiO2nanotube arrays were prepared on Ti substrate by anodic oxidation method. The samples were then annealed to produce a defined anatase structure. The annealed TiO2nanotube arrays were firstly decorated a layer of bovine serum albumin (BSA). Then, the BSA-modified TiO2nanotube array chips were immersed into hydrochloroauric acid solution for decorating TiO2nanotube array with Au3+. Then the resulted chips were exposed to UV light for1h, the Au-modifed TiO2nanotubular hybrids (AuNPs/TiNTs) were achieved. The immobilization of hemoglobin was realized on the surface of AuNP/TiNTs using adsorption method. This paper uses SEM, XRD and EIS techniques to character the preparation of AuNPs/TiO2NT composite membrane materials, the experimental results show that AuNPs were successfully modified on TiNTs,with the diameter about4nm; because of the nanometer-level size, the Au nanoparticles on the surface of TiNT could act as "metal wires" to achieve an effectively improved direct electron transfer between the hemoglobin (Hb) and TiNTs; and a H2O2sensor based on AuNPs/TiNTs was constructed, which was applied to H2O2analysis with the linear range of0.01mmol/L-0.16mmol/L and a detection limit of2μmol/L.