Hydroxyapatite forming ability, ion release and antibacterial activity of the melt-derived SiO2–P2O5–Na2O–CaO–F glasses modified by replacing CaO with SrO and ZnO

Since the discovery of 1970s, bioactive glass has been a hot topic of research because of its excellent biological activity, which makes it a material that can repair and replace human bone tissue organs. In this work, the bioactive glasses in the system SiO2–P2O5–Na2O–CaO–F with different amounts of strontium oxide (SrO) and zinc oxide (ZnO) were prepared by the conventional melt quenching technology. The hydroxyapatite (HA) forming ability, ion release and antibacterial activity of these prepared glasses were investigated and the obtained results illustrated that SrO-doped samples had a better ability to form HA in modified simulated body fluid (MSBF) than ZnO-doped samples. As the immersion time of the sample in MSBF increased, the content of HA phase gradually increased. In the same immersion time, the formation ability of HA and the variation of SrO substitution amount showed a non-linear trend, which is mainly related to the influence of SrO content on the glass network structure. The results of ion concentration showed that the formation of HA was the result of the comprehensive action of various ions in the solution, especially the release rate of Si4+ ions, which had a direct impact on the formation ability of HA. The antibacterial test illustrated that the difference in antibacterial activity of bacteria solution at different sample concentrations may be related to the high pH environment and the osmotic effects caused by the non-physiological concentration of ions in the solution. The glass sample contained 4 wt% SrO showed the minimum bactericidal concentration at 64 mg/mL. The glass samples prepared in this experiment had good biological activity and antibacterial effect, making them suitable for using in dentistry and orthopedic applications, as well as providing a valuable composition reference for the preparation of bioactive glass with excellent comprehensive properties.