Antibacterial Activity of Ag-Doped TiO₂ and Ag-Doped ZnO Nanoparticles

We report in this paper antibacterial activity of Ag-doped TiO 2 and Ag-doped ZnO nanoparticles (NPs) under visible light irradiation synthesized by using a sol-gel method. Structural, morphological, and basic optical properties of these samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectrum, and UV-Vis reflectance. Room temperature X-ray diffraction analysis revealed that Ag-doped TiO 2 has both rutile and anatase phases, but TiO 2 NPs only have the anatase phase. In both ZnO and Ag-doped ZnO NPs, the hexagonal wurtzite structure was observed. The morphologies of TiO 2 and ZnO were influenced by doping with Ag, as shown from the SEM images. EDX confirms that the samples are composed of Zn, Ti, Ag, and O elements. UV-Vis reflectance results show decreased band gap energy of Ag-doped TiO 2 and Ag-doped ZnO NPs in comparison to that of TiO 2 and ZnO. Pathogenic bacteria, such as Staphylococcus aureus , Pseudomonas aeruginosa , and Escherichia coli , were used to assess the antibacterial activity of the synthesized materials. The reduction in the viability of all the three bacteria to zero using Ag-doped ZnO occurred at 60 μ g/mL of culture, while Ag-doped TiO 2 showed zero viability at 80 μ g/mL. Doping of Ag on ZnO and TiO 2 plays a vital role in the increased antibacterial activity performance.