Antibacterial Activity of Nanocrystalline TiO2(B) on Multiresistant Klebsiella pneumoniae Strains

Nanocrystalline TiO2(B) and bi-crystalline (anatase-TiO2(B)) photocatalysts were prepared through hydrothermal synthesis by using different Ti-precursors such as titanium(IV) isopropoxide, titanium(IV) chloride and Degussa P25 TiO2. The obtained TiO2 samples were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and N-2-sorption measurements. Both the single-phase and bi-crystalline photocatalysts were composed of rod-like, polydisperse nanocrystallites as revealed by electron microscopy analysis. The antibacterial activity of the TiO2 samples was tested against three different Klebsiella pneumoniae strains in aqueous dispersions illuminated by UV-A light. We found that UV-A irradiation itself did not decrease the viable cell number of the bacteria. However, TiO2 nanorods irradiated with UV-A light exhibited high antibacterial activity even in the case of the TiO2 samples synthesized under mild reaction conditions without applying any post-annealing step. The photocatalytic activity of the samples was also tested via methyl orange degradation. We found that bi-crystalline anatase-TiO2(B) possessed higher antibacterial and photocatalytic activities than that of single-phase TiO2(B). From these nanostructures, transparent TiO2 thin films of high quality on glass substrates were successfully fabricated by dip-coating method without the use of any additives.