Mechanisms of the enhanced antibacterial effect of Ag-TiO2 coatings.

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.