Antibacterial, osteogenic, and angiogenic activities of SrTiO3 nanotubes embedded with Ag2O nanoparticles.

Biomedical titanium (Ti) implants with good anti-infective, osteogenic, and angiogenic properties are in great demand. SrTiO3 nanotubes (NTs) are embedded with silver oxide (Ag2O) nanoparticles (NPs) (denoted as NT-Sr-Ag) by a hydrothermal treatment of TiO2 NTs containing Ag2O NPs (denoted as NT-Ag) in a Sr(OH)2 solution. The morphology, composition, microstructure, ion release phenomenon, as well as antibacterial, osteogenic, and angiogenic activities are investigated in details. During the hydrothermal treatment, the amorphous TiO2 in the NTs morphs into cubic SrTiO3 gradually and the ordered nanotubular architecture is preserved. Some Ag2O NPs are incorporated into the structure although some of them dissolve in the solution. Long-term bacterial resistance against Staphylococcus aureus is observed as a result of the prolonged and controllable Ag(+) release. NT-Sr-Ag can also release Sr(2+) similarly to stimulate osteoblasts to secrete the vascular endothelial growth factor (VEGF). Both the released Sr(2+) and secreted VEGF upregulate the alkaline phosphatase (ALP) activity and extracellular matrix mineralization of osteoblasts. Furthermore, better angiogenic activity is observed when endothelial cells are cultured in NT-Sr-Ag conditioned media when compared with that in NT-Ag conditioned media, which is believed to be ascribed to the positive regulation of VEGF secretion of Sr(2+). NT-2Sr-Ag and NT-3Sr-Ag (Hydrothermal treatment for 2 and 3h, respectively) exhibit excellent antibacterial, osteogenic, and angiogenic activities and are promising in biomedical implants.