2007 NSTI Nanotechnology Conference and Trade Show - Nanotech 2007 - 10th Annual

Photoactive titania and nanoparticulate silver-titania composite thin films as potent antimicrobial coatings

K. Page, I.P. Parkin and M. Wilson
University College London, UK

Keywords:
titania, photocatalyst, antimicrobial

Abstract:
Nanocrystalline titania (anatase) and Ag-doped titania (anatase) coatings were prepared on glass microscope slides by a sol-gel dip-coating method. The resultant coatings were characterised by X-ray diffraction, XANES, Raman, SEM/WDX, XPS and UV visible techniques and shown to consist of anatase with ca 1 atom % Ag2O. Photocatalytic activity of the coatings was determined by photomineralisation of stearic acid, monitored by FT-IR spectroscopy. Photocatalytically-active coatings were screened for their antibacterial efficacy against Staphylococcus aureus (NCTC 6571), Escherichia coli (NCTC 10418) and Bacillus cereus (CH70-2). Ag-doped titania coatings were found to be significantly more photocatalytically and antimicrobial active than a titania coating. No antimicrobial activity was observed in the dark – indicating that silver ion diffusion was not the mechanism for antimicrobial action. The mode of action was explained in terms of a charge separation model. The coatings also demonstrated significantly higher activity against the Gram-positive organisms than against the Gram-negative. The Ag2O/TiO2 coating is a potentially useful coating for hard surfaces in a hospital environment due to its robustness, stability to cleaning and reuse, and its excellent antimicrobial response.

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