In situ photoexcitation of silver-doped titania nanopowders for activity against bacteria and yeasts

SEM microphotographs of prepared nanopowders at magnification (a) as-prepared sample – Ti-1, (b) sample annealed at 400°C – Ti-2, (c) Ag-doped as-prepared sample – Ti-3, (d) sample annealed at 400°C which was doped by Ag–Ti-4. [Display omitted] ► We synthesize four nanomaterials based on titanium dioxide. ► We obtain materials in different crystalline form. ► We examine antimicrobial activity with respect to UV-A irradiation. ► Photoexcitation of titanium dioxide based nanomaterials increases activity against microbes. Photocatalytic and in situ microbial activityofthe amorphous and annealed states of Ag-doped and un-doped titania were examined. Studiesontheir structure, morphology, composition, and the photo-absorption characteristics of these materials were performed. Theseresultswere correlated with the photocatalytic and microbial activity against methicillin resistant Staphylococcus aureus K324 (MRSA), methicillin susceptible S. aureus ATCC 25923 (MSSA), Escherichia coli PA 170, and yeasts Candida albicans ATCC 90028. The annealed powders containing anatase form of titania exhibited relatively higher photocatalytic activity,correspondingto activity against MRSA,when exposed to UV-A radiation. In comparison, amorphous powders exhibited low photoactivity and showed poor antibacterial performance against MRSA under UV-A exposure. Doping of amorphous titania with Ag resulted in an anti-MRSA effectwithoutexposure to UV radiation. In the Ag-doped crystalline anatase samples, the size of Ag primary nanocrystallites increased, which led tothedecrease in the surface concentration of Aganddetrimentanti-MRSA activity.