| Project/Area Number |
05557071
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Urology
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| Research Institution | Yokohama City University |
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Principal Investigator |
KUBOTA Yoshinobu Yokohama City Univ., School of Med, Ass.Professor, 医学部, 助教授 (10106312)
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| Co-Investigator(Kenkyū-buntansha) |
HASHIMOTO Kazuhito Univ.Tokyo, School of Engineering, Ass.Professor, 工学部, 助教授 (00172859)
FUJISHIMA Akira Univ.Tokyo, School of Engineering, Professor, 工学部, 教授 (30078307)
HOSAKA Masahiko Yokohama City Univ., School of Med, Professor, 医学部, 教授 (30106330)
川崎 千尋 横浜市立大学, 医学部, 講師 (20234057)
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| Project Period (FY) |
1993 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1994: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1993: ¥3,800,000 (Direct Cost: ¥3,800,000)
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| Keywords | photoexcited semiconductor / TiO2 / Bladder cancer / 光半導体癌法 |
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| Research Abstract |
A photoexcited titanium dioxide surface has a strong ability to decompose water into hydrogen and oxygen. We have studied this effect in order to use it to kill cancer cells in vitro and in vivo. A distinct cell killing effect was observed on cultured T-24 human bladder cancer cells treated with titanium dioxide particles and 300-400 nm UV light irradiation. Titanium dioxide plus UV light also dramatically suppressed the tumour growth of T-24 cells that were implanted in nude mice. Cells cultured on the titanium dioxide electrode were also killed under UV irradiation when the electrode was anodically polarised, suggesting that photogenerated holes are involved in the cell killing. The cell killing effect caused by titanium dioxide particles plus UV light irradiation was significantly hampered in the presence of L-cysteine and catalase, scavengers of hydroxyl radicals and hydrogen peroxide respectively. Transmission electron microscopic observations showed the titanium dioxide particles to be distributed on the cell surface and inside the cells. These results suggest that titanium dioxide particles under UV light irradiation produced photogenerated holes on the surface yielding hydroxyl radicals and hydrogen peroxide inside or outside the cells and the cells were then killed by the action of these highly oxidising molecules. The possible application of photoexcited titanium dioxide particles to cancer treatment as a new anti-cancer modality is discussed.
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