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 μW) 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 108–109 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.

Both reactive oxygen species such as hydroxyl radical generated under weak ultraviolet irradiation and Ag species from silver-modified mesoporous TiO2 cooperatively broke up cell membrane, leading to cell death.Figure optionsDownload as PowerPoint slideHighlights
► Ag-modified mesoporous TiO2 inactivates bacteria under weak ultraviolet irradiation efficiently.
► The equilibrium between Ag+ ions and Ag0 sustains the long-term antibacterial activity of TiO2-Ag.
► An optimal amount of Ag deposited on TiO2 enhances the antibacterial activity.