Undoped and Cdoped TiO

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films have been prepared by sol-gel process. The chemical components of the TiO

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:C composite thin film were characterized using X-ray Photoelectron Spectroscopy（XPS）. The antibacterial efficacy of the TiO

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:C composite film was tested by film applicator coating method. Antibacterial mechanism of TiO

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:C composite film was discussed by transmission electron microscope（TEM）. It has been observed that C dopants retard the transformation from anatase to rutile phase. Namely

C doping effect is attributed to the anatase phase stabilization. More than 90% of bacterium were killed within 20 minutes which confirm fine antibacterial effect of the film.When studying the ultrastructure changes as the antibacterial material of TiO

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:C thin film against Escherichia coli，the work indicated that the antibacterial particles of TiO

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:C thin film may produce active oxides which contact the Escherichia coli cell and damage even penetrate the cells wall and plasmolemma to enter into the core to make cytoplasm agglomerate and thus cause the cells dead.