Antibacterial Activity of ZnSe, ZnSe-TiO2 and TiO2 Particles Tailored by Lysozyme Loading and Visible Light Irradiation

ZnSe, ZnSe-TiO2 microspheres and nanostructured TiO2 obtained by hydrothermal and sol-gel methods were tested against Staphylococcus aureus ATCC 25923 and Micrococcus lysodeikticus ATCC 4698 before and after lysozyme (Lys) loading. Morphological characterization of inorganic matrices and hybrid organic-inorganic complexes were performed by microscopy techniques (SEM, AFM and Dark Field Hyperspectral Microscopy). Light absorption properties of ZnSe, ZnSe-TiO2 and TiO2 powders were assessed by UV-visible spectroscopy and their ability to generate reactive oxygen species (center dot OH and O-2(center dot-)) under visible light irradiation was investigated. Antibacterial activity of ZnSe, ZnSe-TiO2, TiO2, Lys/ZnSe, Lys/ZnSe-TiO2 and Lys/TiO2 samples under exposure to visible light irradiation (lambda > 420 nm) was tested against Staphylococcus aureus and Micrococcus lysodeikticus and correlated with ROS photogeneration.