Antimicrobial activity of titania/silver and titania/copper films prepared by CVD

We have previously reported the production of photocatalytically active films of TiO2/Ag and TiO2/CuO grown by atmospheric pressure thermal CVD that had high antimicrobial activity. The present study compares the activity of dual layers and co-deposited TiO2–CuO with single layers. We also compared the BS ISO 27447:2009 method with our previously reported method for determining photocatalytic antimicrobial activity and showed that although the activity was reduced in the BS method, probably due to the lower UV irradiation used, there was still a good antimicrobial activity. The results showed that Ag–TiO2 surfaces retained photocatalytic self-cleaning activity measured by stearic acid oxidation whereas Cu–TiO2, both layered and co-deposited had very low activity. However, both were antimicrobial against Escherichia coli with activity of the Cu–TiO2 films greatly enhanced by irradiation possibly via a photo-Fenton type reaction. The activity of the Ag–TiO2 films against Pseudomonas aeruginosa and MRSA (methicillin resistant Staphylococcus aureus) showed reduced killing activity with an environmental isolate of P. aeruginosa and the MRSA showing only 3 log and 1.5 log reductions respectively. The implications for their use for reduction of surface contamination by microorganisms as part of control measures for healthcare associated infections are discussed.