Enhanced inactivation of bacteria with silver-modified mesoporous TiO2 under weak ultraviolet: irradiation

The efficient antibacterial activity of silver-modified mesoporous TiO2 materials with different silver contents were investigated under weak ultraviolet light (UVA) (200 mu W) irradiation using Escherichia coli (E. coli) as a model strain. The comparison with the antibacterial results of three silver-modified TiO2 photocatalysts indicated that sample TiO2-Ag2.0% with 2.0 wt.% of Ag exhibited the highest antibacterial activity with 10(8)-10(9) CFU/mL E. coli being completely inactivated in 150 min. The photocatalytic destruction of E. coli cells was observed directly from field-emission scanning electron microscope and transmission electron microscope images and confirmed by using the confocal laser scanning microscopy technique, demonstrating that the surface of bacteria cells were covered by silver-modified TiO2 and the cell membrane was damaged seriously. Experimental results also revealed that an optimal amount of Ag deposited on TiO2 promise a good stability of silver-modified TiO2 materials. (C) 2011 Elsevier Inc. All rights reserved.