Enhanced inactivation of Escherichia coli with Ag-coated TiO2 thin film under UV-C irradiation

The inactivation of Escherichia coli (E. coli) in water was investigated systematically with Ag-coated TiO₂ thin film under UV-C irradiation. Compared with UV-C irradiation alone, the inactivation of E. coli by the UV/Ag-TiO₂ process was enhanced and the photoreactivation of the bacteria was much repressed. Moreover, atomic force microscopy (AFM) measurements of E. coli showed that the presence of Ag-TiO₂ thin film during UV exposure could expedite the destruction of cell wall and cell membrane, which was further confirmed by the formation of malondialdehyde (MDA) and leakage of intracellular potassium ion (K⁺) and protein. The results suggest that the cell structure destruction might be the major reason for the enhancement of inactivation efficiency, and the prepared Ag-TiO₂ thin films show potential as a new improvement tool for UV-C disinfection.