Influence of strontium on the structure and biological properties of sol-gel-derived mesoporous bioactive glass (MBG) powder

In the recent years, considerable attention has been paid to strontium (Sr) for its therapeutic effects on bone diseases such as osteoporosis. In this study, a series of sol-gel-derived bioactive glasses based on SiO2-CaO-SrO-P2O5 quaternary system was synthesized, in which 0-100 % of the calcium was substituted by strontium. The influence of strontium on structural and biological behavior of the bioactive glasses was evaluated. The XRD analysis showed Sr-free sample to be amorphous without any significant crystalline phases. As the Sr content increased in the glasses, the tendency toward crystallization enhanced. Results of BET analysis confirmed the mesoporous texture (mean pore diameter: 9.16 nm) with a high specific surface area (39.7 m(2) g(-1)) for the glass powders. Bioactivity of the system was studied by immersing the glass powders in simulated body fluid for 3, 7, and 14 days. The presence of strontium significantly accelerated the formation of hydroxyapatite layer onto the surface of glass particles. Besides hydroxyapatite, strontium apatite (Sr-10 (PO4)(6)OH2) was formed onto the surface of Sr-containing bioactive glasses. The present study also investigated the osteoblast response to the Sr-containing bioactive glasses in vitro. Results indicated increased metabolic activity of osteoblasts in the Sr-containing bioactive glasses.