Synthesis Of Titanium Dioxide Nanocomposite Materials For Photoinactivation Of Bacteria Under Visible Light

Nano antibacterial material has become an import part of life science because of its small particle diameter, high specific surface area, volume effect and quantum size effect. TiO2 is a kind of great semiconductor material, but it can only show its bactericidal activity under UV-light because its narrow band gap. Therefore, many people are focusing on preparing a kind of nano antibacterial material which can show high bactericidal activity under visible light. In this work, we prepared a kind of nano composite material based on TiO2 which can show its highly bactericidal activity under visible irradiation in very short time.In the first part, we synthesized magnetically core-shell Ag3PO4/TiO2/Fe3O4 heterostructured nanocomposite. Also we explored its photocatalytic activity and bactericidal activity. As the valence band (VB) level of the Ag3PO4 is located lower than that of TiO2, the holes that photogenerated in Ag3PO4 can transfer to TiO2, and these energetic holes in the VB of TiO2 are able to initiate in turn various oxidation reactions. Therefore, combining Ag3PO4 with TiO2 to form hetrostructure is regarded as an effective strategy to achieve efficient photocatalyst with high photocatalytical activity under visible light irradiation. The result shows our material can cause bacteria’s death in very short time under visible irradiation. Meanwhile, the material has great recyclability. The bactericidal efficiency can reach 60% when the material had been used 5 times.In the second part, we demonstrate the fabrication of an amphiphilic TiO2 nanotubular structure which can provide a highly controllable drug release under visible light. This hydrophobic cap prevents uncontrolled leaching of the hydrophilic drug into an aqueous environment. When the system is under visible light, the shift can be turn on and a highly controlled release of drugs can be achieved. First we introduce AuNPs onto the surface of TiO2 nanotubes to make it can absorb visible light. Then OPDA was used to build a hydrophobic layer. At last, we conducted coupling agent to TiNTs. The coupling agent can connect AMP with TiNTs in order to loading drug. We conduct a series of experiments, and the result shows that the system won’t release drug in dark. When the system is under visible light, the switch can be turned on and drug is released.