Formulating Single Phasic Silicorhenanite (α- and β-Na2Ca4(PO4)2SiO4) Bioactive Glass Materials Competing with Commercial Crystalline Hydroxyapatite Bone Mineral for Biomedical Applications.

Hydroxyapatite (HAP) is a well-known medically renowned bioactive material known for its excellent biocompatibility and mechanical stability, but it lacks fast bioactivity. The restricted release of ions from hydroxyapatite encourages the search for a faster bioactive material that could replicate other properties of HAP. A new sol-gel-mediated potentially bioactive glass material that could mimic the structure of HAP but can surpass the performance of HAP bioactively has been formulated in this study. Lefebvre et al. suggested that the silicorhenanite phase with the formula Na₂Ca₄(PO₄)₂SiO₄ is isostructural to hydroxyapatite; however, data in support of this hypothesis are scant. This study succeeds in developing fast apatite-growth-inducing bioactive glass particles similar to the structure of hydroxyapatite. Also, for the first time, the existence and evolution of two forms of silicorhenanite (α- and β-Na₂Ca₄(PO₄)₂SiO₄) have been unraveled, and their properties have been explored. The effect of calcination temperature on the phase formation of the biomaterial is notified by looking into the result that heat treatment to 900 °C resulted in α-Na₂Ca₄(PO₄)₂SiO₄ (Sili 900) and 1000 °C yielded β-Na₂Ca₄(PO₄)₂SiO₄ (Sili 1000). This study conveys a new finding that the hydroxyapatite is isostructural to β-Na₂Ca₄(PO₄)₂SiO₄ but not to α-Na₂Ca₄(PO₄)₂SiO₄. Raman spectroscopic analysis proved this structural similarity of Sili 1000 and c-HAP, with relative spectra possessing phosphate bands and the irrelevance of Sili 900 to Sili 1000 and c-HAP. The in vitro MTT assay using NIH 3T3 fibroblasts and in vivo wound healing study confirm the enhanced bioactivity and compatibility of Sili 900 and Sili 1000 compared to c-HAP, favored by the presence of a silica matrix and semicrystallinity. pH analysis proved the rapid ionic leaching out from Sili 900 and Sili 1000 and the faster reactivity of Sili 1000 with the fluid. This rapid burst of ions enhances the clotting ability of the Sili 1000 bioactive material and can be a good ibuprofen drug carrier, which is a potential challenger to hydroxyapatite.