Antibacterial activity of thin-film photocatalysts based on metal-modified TiO2 and TiO2:In2O3 nanocomposite

Photoinduced bactericidal activity of nanostructured TiO2 and TiO2:In2O3 films and the effect of deposition of silver and bimetallic Ag/Ni nanoparticles on the pathophysiological properties of titania films were investigated. The antimicrobic activity of the films was assessed against Psedomonas fluorescens B-22 (gram-negative bacterium) and Lactococcus lactis ssp. lactis 411 (gram-positive bacterium). The silver-modified TiO2 film demonstrates the highest photobiocide efficiency, enhancing the bactericidal activity of UV light ca. 71-fold, that results from radical improvement of microorganism adsorption and suppression of recombination of photoproduced charge carriers. Higher inactivation rate observed for P.fluorescens as compared to L. lactis can be explained in terms of comparative morphologies of the cell envelops of gram-negative and gram-positive microorganisms and the resistance of their outer membranes to the reactive oxygen species generated by photocatalytic reactions. (c) 2008 Elsevier B.V. All rights reserved.