Binary Doping of Strontium–Magnesium to Bioactive Glasses to Enhance Antibacterial and Osteogenic Effects

Bone defects that exceed the critical defect value, resulting from fractures and diseases, are often difficult to heal. Although bone tissue engineering is a promising treatment for extensive osseous defects, orthopedic-implant-related infections increase the likelihood of failure. Bioactive glass (BG) has been widely used in the manufacture of artificial bone scaffolds, owing to its excellent biocompatibility and osteoinductivity. Nevertheless, considering that infection conditions and trauma can affect the osteogenic capacity of bioactive glass, this study combined BG with magnesium and strontium to promote osteogenesis and confer significant antimicrobial activity. Novel bioactive glass doped with magnesium-strontium (BGMSN) with good biocompatibility, excellent antibacterial properties, and promising osteogenic induction ability was constructed from 45S5, Mg, and Sr carbonates via a melt-quenching approach. The results of an <i>in vitro</i> cell biocompatibility study indicated that the BGMSN exhibited good cellular compatibility. Furthermore, osteogenic alkaline phosphatase, osteocalcin, and osteopontin genes were upregulated upon BGMSN/MC3T3-E1 coculture. BGMSN exhibited potent <i>in vitro</i> antibacterial effects against <i>Staphylococcus aureus</i>, <i>Escherichia coli</i>, and <i>Streptococcus mutans</i>. Animal experiments further demonstrated the exceptional bone-inducing ability of BGMSN. Accordingly, owing to their excellent antimicrobial properties, BGMSN can be used for bone regeneration, particularly under infected conditions.