Phosphate Content Affects Structure And Bioactivity Of Sol-Gel Silicate Bioactive Glasses

Bioactive glasses can heal bone defects and bond with bone through formation of hydroxyl carbonate apatite (HCA) surface layer. Sol-gel derived bioactive glasses are thought to have potential for improving bone regeneration rates over melt-derived compositions. In this article, hydroxyapatite (HA) was found to form within the 58S glass during sol-gel synthesis after thermal stabilisation. The preformed HA may lead to rapid release of calcium orthophosphate, or nanocrystals of HA, on exposure to body fluid, rather than the release of separate calcium and phosphate species. Increasing P2O5 to CaO ratio in the glass composition reduced preformed HA formation, as observed by XRD and solid-state NMR.