Tailoring bioactive and mechanical properties in polycrystalline CaO–SiO₂–P₂O₅ glass-ceramics

Biological functions and mechanical properties are vital factors for artificial bone materials, with great clinic demand for bone injuries and defects. This study highlights mechanical strengths, in vitro and in vivo biological behaviors of the bioactive CaO–SiO₂–P₂O₅ glass-ceramics tailored by the nucleating agent P₂O₅. A high mechanical flexural strength of ∼170 MPa and hardness of ∼720 HV were achieved, owing to strengthened Si–O bonds in the network. In vitro cell tests demonstrate remarkable viability (using L929 cells) and bioactivity (using bone marrow-derived mesenchymal stromal cells), associated with the release of Ca²⁺ ions in the solution due to weakened Ca–O bonds in the glass-ceramic network. The assay in the simulated body fluid revealed a formation of the hydroxyapatite-phase layer, which may act as a bridge to facilitate bioactivity on the CaO–SiO₂–P₂O₅ glass-ceramics. In vivo assay shows a significant bone-ingrowth capability on the CaO–SiO₂–P₂O₅ glass-ceramic. This work paves a promising route to utilize P₂O₅–nucleated CaO–SiO₂–P₂O₅ glass-ceramics for load-bearing bone replacement.