A functionalized Sm/Sr doped TiO2 nanotube array on titanium implant enables exceptional bone-implant integration and also self-antibacterial activity

Abstract Effective bone repair applications of titanium-based biometals must have excellent self-antibacterial properties and osteogenesis. Due to the special nano-geometric structure of titanium dioxide nanotubes (TN), the modified TN can confer various biological functions on the surface of titanium-based biometals. In this study, we used anodization, hydrothermal synthesis, and dopamine self-assembly to develop a Sm/Sr-doped TN (SSNT) array that integrated the antibacterial properties of Sm and the bone formation properties of Sr. AFM, SEM, FTIR, EDS, and XPS methods were used to characterize the SSTN, and the antibacterial and cell compatibility of the SSTN were systematically studied. Sm ions and Sr ions were slowly and stably released from the surface of dopamine and SrTiO3 crystals, respectively. Compared with TN, SSTN had a smaller roughness and significantly improved hydrophilicity. The colony count, inhibition zone and turbidity experiments demonstrated that the SSTN structure containing Sm had obvious antibacterial effect on E. coli and S. aureus. The nanotube structure containing strontium ions can promote the early differentiation and osteogenic gene expression of MC3T3-E1 cells adhered to the SSTN surface. Based on the above results, the dual doping of Sm and Sr, and the ideal hydrophilicity can not only improve the osteogenesis of titanium-based biometals, but also make such bone implant biometals have effective self-infection resistance.