The effects of titania nanotubes with embedded silver oxide nanoparticles on bacteria and osteoblasts

A versatile strategy to endow biomaterials with long-term antibacterial ability without compromising the cytocompatibility is highly desirable to combat biomaterial related infection. TiO₂ nanotube (NT) arrays can significantly enhance the functions of many cell types including osteoblasts thus having promising applications in orthopedics, orthodontics, as well as other biomedical fields. In this study, TiO₂ NT arrays with Ag₂O nanoparticle embedded in the nanotube wall (NT-Ag₂O arrays) are prepared on titanium (Ti) by TiAg magnetron sputtering and anodization. Well-defined NT arrays containing Ag concentrations in a wide range from 0 to 15 at % are formed. Ag incorporation has little influence on the NT diameter, but significantly decreases the tube length. Crystallized Ag₂O nanoparticles with diameters ranging from 5 nm to 20 nm are embedded in the amorphous TiO₂ nanotube wall and this unique structure leads to controlled release of Ag⁺ that generates adequate antibacterial activity without showing cytotoxicity. The NT-Ag₂O arrays can effectively kill Escherichia coli and Staphylococcus aureus even after immersion for 28 days, demonstrating the long lasting antibacterial ability. Furthermore, the NT-Ag₂O arrays have no appreciable influence on the osteoblast viability, proliferation, and differentiation compared to the Ag free TiO₂ NT arrays. Ag incorporation even shows some favorable effects on promoting cell spreading. The technique reported here is a versatile approach to develop biomedical coatings with different functions.