Highly effective visible light-activated cobalt-doped TiO2 nanoparticles for antibacterial coatings against Campylobacter jejuni

Pure and cobalt-doped nanocrystalline TiO2 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 TiO2 structure. The crystalline phases and particle-size study of the pure and doped TiO2 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 TiO2 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.