Non-UV germicidal activity of fresh TiO2 and Ag/TiO2 |
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Authors: | LIU Lifen John Barford and YEUNG King Lun |
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Institution: | 1. Key Lab of Industrial Ecology and Environmental Engineering, MOE Ministry of Education of China, School of Environmental & Biological Science and technology, Dalian University of Technology, Dalian 116024, China;Department of Chemical Engineering,Hong Kong University of Science and Technology, Clear water Bay, Kowloon, Hong Kong 999077, China 2. Department of Chemical Engineering,Hong Kong University of Science and Technology, Clear water Bay, Kowloon, Hong Kong 999077, China |
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Abstract: | Fresh TiO2 was found to possess a strong germicidal activity even without UV irradiation. Live Yeast (Saccharomyces cerevisiae) cells in contact with fresh TiO2 were found deformed and dead after 15 min contact. The cause of germicidal activity was discussed from the observed cell deformation, lysis and increased absorption at 1680 cm-1 in FT-IR spectra of the affected cells, which proved the oxidizing effect of fresh TiO2 to cells. The deformation caused by the stretching of cell wall and pressure built-up inside the cell, led to cell burst and release of intracellular materials. The degree of cell deformation was found positively related with the wetting property of TiO2. Cells are negatively charged, for Gram-negative cell (thinner cell wall), a higher germicidal effect was observed than Gram-positive cells. The germicidal effect of TiO2 gradually decreases after exposure to air at room temperature, as the wetting property decreases. This kind of germicidal activity was more effective compared to other germicidal process such as UVA/TiO2 or Ag+. This shed light on designing new germicidal material either maintained by visible light irradiation, or by oxidation effect generated by reactive oxygen species. |
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Keywords: | germicidal activity titanium dioxide non-UV |
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