Targeted Nano-oxide Semiconductor Photocatalytic Oxidation, Electrochemical Methods Of Anti-cancer Research

Nano-size titanium dioxide (TiO₂) and zinc oxide (ZnO) are n-type semiconductors with similar valence band structure. As semiconductors, TiO₂ and ZnO nano-particles have a good photoactive ability and can absorb the light with the wavelength shorter than 380 nm, and creating electron-hole pares, which in the aqueous environment can decompose organic molecules and kill bacteria and cells. In this work, we put forward the technology of combination of antibody-TiO₂ nanoparticls, electroporation, and photocatalysis ability of TiO₂ to improve the selectivity and the efficiency of photokilling for LoVo cancer cells.The main contents of this paper are:1. The technology of combination of the antibody-nano-TiO₂, electroporation and photocatalysis presents the ability to improve the selectivity and efficiency of the TiO₂ nano-particles in photo-killing LoVo cancer cells.This process was investigated using fluorescence microscopic, TEM and single cell gel electrophoresis mehtods. It was found that the antibody modified nano-TiO₂ conjugates could initiatively attached on the membrane of LoVo cancer cells. They could enter into the cancer cells under the electric pulse, and located around the cell nucleolus mainly. Under the irradiation of UV light with wavelength 254 nm, the photocatalysis effect of nano-TiO₂ happened inside of cells, and to damage the DNA in the organs, karyotheca and nucleolus of cells heavily and finally put the LoVo cells to death. So that this new method not only shows good selectivity, but also increase the efficiency in photokilling LoVo cancer cells obviously.2. Owning similar valence band structure as TiO₂, good bioconjugation material ZnO also has photocatalysis abilities. We tried to adopt the similar method to test the photokilling effect of ZnO as that for nano-TiO₂ on bacteria and LoVo cancer cells. Two kinds of ZnO, nano size ZnO and needl like micro size ZnO, were prepared by sol-gel and precipitation methods respectively. The pilot study results showed that nano ZnO presented better effect in the inhibiting the growth of Escherichia coli and LoVo cells more than needle like micro ZnO in low concentration. It was found that the nano ZnO also presented obvious ability for photokilling LoVo cells.3. The inflency of electric field on the tumors is an intresting project, which attract many research groups' attention in the world recently. In the nude mice experiment, we tested the effect of electric field with square wave, short pulse, and combined with high frequency a.c electric field on LoVo cell tumours. It was found that when 70-80 V square wave combined with high frequency electric field was used the LoVo tumour could be damaged and healed in less than four weeks' treatment, and only leaving a smooth scar in the skin of naked mice. These effects could be attributed to the heating effect mainly. When 150 V pulse combined with high frequency electric field was used, the LoVo tumour could be damaged by use of short time treatment. It indicated that the electric field also presents the high effect on destroys the LoVo tumour. It was also found that the injection of surfactants into the tumours could help to improve the curative effect.