Antibacterial activities of Nd doped and Ag coated TiO2 nanoparticles under solar light irradiation

Nanosized (8–9 nm) Nd doped and Ag coated TiO2 nanoparticles have been synthesized by sol–gel method. The physicochemical properties of these particles were investigated by X-ray diffraction (XRD), diffuse reflectance UV–visible (DRUV) spectra and Brunauer–Emmett–Teller (BET) surface area analysis. The antibacterial activities of the samples were studied for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) both, under the light and dark conditions. The results reveal that the extent of activity shows the order as undoped TiO2 < Nd doped TiO2 < Ag coated TiO2. The mechanism of bactericidal action of the nanoparticles, in presence of sunlight has been explained with the help of microscopic analyses. The bacterial damage is observed to proceed through initial perforation of the cell, damage of cell wall and finally the bacterial death.