Preparation Of TiO₂-based Nanocomposites Via Surface Plasma Modification And Their Application On Biosensing

This paper investigated the properties of titanium dioxide?TiO₂? as matrix material to prepare biosensor. In order to improve the biocompatibility of TiO₂, the plasma enhanced chemical vapor deposition polymer acrylic acid was employed to modify the surface of hollow TiO₂ spheres. Then the development of electrochemical biosensor based on composite was used to detect protein or heavy metal ions by immobilizing aptamer and Rhodamine B hydrazide?RhB?. The electrochemical impedance spectroscopy was adopted to detect the different concentrations of lysozyme and Cu²⁺. Finally, the biosensors were applied into real blood test for medical diagnosis.This paper mainly includes three aspects, the plasma surface modification of titanium dioxide materials as matrix were developed the electrochemical sensors and evaluated its performance in the actual tests:The hollow TiO₂ sphere was synthesized with the carbon sphere as template. Subsequently, it was investigated that the chemical structure, surface morphology, and electrochemical performance of the TiO₂@PPAA composite affected by the plasma input power used during plasma polymerization and reaction time. The plasma input power of 20 W, 50 W and 100 W was adopted to prepare TiO₂@PPAA composite. It could be found that the content of carboxyl groups was the highest at plasma input power of 20 W. Along with the deposition time increasing, the content of carboxyl group and thickness of film increased. Therefore, we chose of the plasma input power of 20 W as reaction conditions for preparing composite film.A composite made of plasma polymerization acrylic acid and hollow Ti O2 spheres?TiO₂@PPAA? was used as an electrode material for detecting lysozyme. The carboxyl groups of TiO₂@PPAA composite was activated by EDC/NHS. TiO₂, PPAA and TiO₂@PPAA composite as the sensitive membrane were detected the lysozyme and the data was collected by EIS method. Because of TiO₂@PPAA composite exhibiting the larger surface area based on three-dimensional structure, the more biomolecules could immobilized on the surface of the composite. The developed biosensor was applied to detect lysozyme. The detection linear range was 0.05-100 ng·mL-1 and the limit of dectecion was 0.015 ng·m L-1?1.04 pM?. It was lower than the reported results. Furthermore, it showed high selectivity in BSA, thrombin and IgE solution. Finally, it has potential application value to detection of lysozyme in egg white and blood test.TiO₂ and PPAA could adsorb the heavy metals on the basis of previous research. This composite was further used as an electrochemical sensor for an ultra-sensitive and selective detection of Cu²⁺ in water. Considering the synergistic effect of strong electrostatic interaction between the carboxyl groups of PPAA and metal ions, the composite was prepared. Meanwhile, the coordination structure was formed between Cu²⁺ and rhodamine. So the h-TiO₂@PPAARhB composite was used as sensitive material. The developed electrochemical biosensor exhibited a high sensitivity of Cu²⁺ detection. The limit of detection of was 0.404 pM within the range of 0.001-10 nM of Cu²⁺. And it showed high selectivity to Pb²⁺?Zn²⁺?Ni²⁺?Co²⁺?Mn²⁺?Mg²⁺ solution. Therefore, the fabricated electrochemical sensor based on TiO₂@PPAARhB can be obtained via plasma polymerization. It represents a highly promising tool for environmental monitoring.In a word, the TiO₂@PPAA composites were applied to fabricated sensors, which could enhanced the limit of detection and selective.