Synthesis of Silver- and Strontium-Substituted Hydroxyapatite with Combined Osteogenic and Antibacterial Activities

Infection in bone transplantation process is attracting considerable attention. The current study synthesizes silver/strontium co-substituted hydroxyapatite (Ag/Sr-HA) nanoparticles with combined osteogenic and antibacterial activities. Different concentrations of silver-substituted hydroxyapatite (Ag-HA) nanoparticles were synthesized by hydrothermal method, and then their physicochemical properties were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDS). Then, Sr was added as secondary element into Ag-HA to improve the biocompatibility of substrate. The antibacterial experiments indicated that Ag-HA had excellent antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The effects of prepared samples on cell proliferation and differentiation were evaluated using MC3T3-E1 cells in vitro. The results showed that Sr substitution enhanced cell proliferation and differentiation, upregulated expression of osteogenic genes, and induced mineralization of cells. The substitution of Sr in Ag/Sr-HA nanoparticles can effectively alleviate the negative effects of Ag and enhance the biological activity of HA. Thus, the synthesized Ag/Sr-HA nanoparticles will serve as a potential candidate for application of biomedical implants with excellent osteogenic and antibacterial ability.