Highly effective visible light-activated cobalt-doped TiO 2 nanoparticles for antibacterial coatings against Campylobacter jejuni

Pure and cobalt-doped nanocrystalline TiO 2 nanostructures, with different concentrations of cobalt (1, 2.5, 5, 10 mol%), were synthesized by a simple hydrothermal route and their antibacterial activity was tested. The corresponding structural and chemical properties of the as-synthesized nanoparticles clearly suggested the occurrence of lattice defects in TiO 2 structure. The crystalline phases and particle-size study of the pure and doped TiO 2 nanoparticles showed the formation of highly pure anatase phase with grain sizes ranging between 7 and 14 nm, where the functional groups and bond lengths were observed through Fourier transform infrared (FTIR) analysis. Raman spectroscopy analysis displayed the broadening of Raman peaks and a systematic frequency shifts with increase in cobalt concentration because of the reduced particle size. Moreover, UV–Vis spectroscopy indicated the visible light absorption of TiO 2 with increase in the concentration of cobalt, which suggests decrease in the energy bandgap. Furthermore, these visible light-activated photocatalysts showed enhanced antibacterial activity in particular against notorious foodborne Gram negative pathogen i.e., Campylobacter jejuni . Moreover, these high energy photocatalysts were able to effectively kill waterborne Gram negative pathogen i.e., Vibrio cholerae as well as foodborne Gram positive pathogen i.e., Staphylococcus aureus . Therefore, we believe that these visible light-activated photocatalysts may be used as broad spectrum antimicrobial agents against groups of such pathogens impacting significantly human health and economy.