Rapid photokilling of gram-negative Escherichia coli bacteria by platinum dispersed titania nanocomposite films

Superior antimicrobial activity of 2 wt.% Pt-dispersed TiO2 thin film was observed in photokilling Gram-negative Escherichia coli bacteria within 5 min irradiation (640 μW cm−2, λ > 340 nm) from UV torch than bare TiO2 film. Severe disruption of cell membrane has occurred over illuminated Pt-TiO2 catalysts films coated with 100–300 μg powders per 5 cm2 areas over sterilized glass slides. The Pt dispersion onto TiO2 by impregnation–hydrogen reduction always exhibited better photokilling effect than Pt photodeposition, irrespective of Pt–TiO2 dose and light exposure time. Similar trend in photoactivity difference between two Pt–TiO2 catalysts is also observed in aqueous slurry because of the unlike surface structure of TiO2 due to different annealing temperatures, size and nature of Pt particles dispersion onto TiO2 photocatalysts.