BIOCHEMICAL APPLICATION OF PHOTOELECTROCHEMISTRY - PHOTOKILLING OF MALIGNANT-CELLS WITH TIO2 POWDER

Photoexcited TiO2 electrodes have a strong ability to decompose water into hydrogen and oxygen. Here this effect is utilized to kill cancer cells in vitro and in vivo. When the potential of the TiO2 electrode was applied to +0.5 V, the cells cultured on the TiO2 electrode were completely killed under uv light irradiation, but were alive without uv light irradiation. The reduction of cell viability is proportional to the increase in anodic photocurrent, suggesting that the photogenerated holes are involved in the cell killing. In order to apply this effect to cancer therapy, TiO2 particles were used instead of TiO2 electrode, which function as a microphotocell. A distinct cell killing effect was also observed by treatment with TiO2 particles and uv light irradiation. In experiments comparing the killing effects using TiO2 particles alone and TiO2 particles with uv irradiation, the photoexcited TiO2 particles significantly suppressed the growth of HeLa cells that were implanted in nude mice. On the basis of these experimental observations, it can be concluded that the cell killing effect of TiO2 under uv light irradiation could be adopted as one of anti-cancer modality.