Carbon spheres assisted synthesis of porous bioactive glass containing hydroxycarbonate apatite nanocrystals: A material with high in vitro bioactivity

A hierarchically porous bioactive glass of composition 80 mol % SiO2 and 15 mol % CaO (MBGH) was synthesized using pluoronic P123 and glucose-derived amorphous carbon spheres as templates. While the carbon spheres leave behind pores of 300 nm to a few micrometers after calcination, the walls of these pores contain orderly arranged mesopores of 3-5 nm orchestrated by the pluoronic polymer. The role of carbon spheres is not only to create pores but also to aid in increased growth rate of hydroxycarbonate apatite in simulated body fluid (SBF). The negatively charged carbon spheres favor the local enrichment of calcium ions and facilitate the formation of amorphous calcium phosphate around the surface. On calcination, the walls of the macropores contain crystalline hydroxycarbonate apatite nuclei. MBGH also exhibits an accelerated growth of monoclinic-like apatite in SBF. The in vitro activity has been studied by XRD, FT-IR, FESEM, and TEM.