Mechanisms of the enhanced antibacterial effect of Ag-TiO₂ coatings

Abstract

It has been demonstrated that Ag-TiO₂ nanocomposite coatings with excellent antimicrobial activity and biocompatibility have the potential to reduce infection problems. However, the mechanism of the synergistic effect of Ag-TiO₂ coatings on antibacterial efficiency is still not well understood. In this study, five types of Ag-TiO₂ nanocomposited coatings with different TiO₂ contents were prepared on a titanium substratum. Leaching tests indicated that the incorporation of TiO₂ nanoparticles into an Ag matrix significantly promoted Ag ion release. Surface energy measurements showed that the addition of TiO₂ nanoparticles also significantly increased the electron donor surface energy of the coatings. Bacterial adhesion assays with Escherichia coli and Staphylococcus aureus demonstrated that the number of adhered bacteria decreased with increasing electron donor surface energy. The increased Ag ion release rate and the increased electron donor surface energy contributed to an enhanced antibacterial efficiency of the coatings.