Photocatalytic antibacterial performance of TiO(2) and Ag-doped TiO(2) against S. aureus. P. aeruginosa and E. coli

This paper reports the structural and optical properties and comparative photocatalytic activity of TiO(2) and Ag-doped TiO(2) nanoparticles against different bacterial strains under visible-light irradiation. The TiO(2) and Ag-doped TiO(2) photocatalysts were synthesized by acid catalyzed sol–gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO(2) has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO(2) nanoparticles. The decreased band-gap energy of Ag-doped TiO(2) nanoparticles in comparison to TiO(2) nanoparticles was investigated by UV–vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron–hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO(2) and Ag-doped TiO(2) nanoparticles (3% and 7%) was investigated against both gram positive (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concentrations of Ag-doped TiO(2) nanoparticles. Annealed TiO(2) showed zero viability at 80 mg/30 mL whereas doped Ag-TiO(2) 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.