Enhanced mechanical and biocompatible properties of strontium ions doped mesoporous bioactive glass

Very low (<= 0.2%) strontium (Sr) ion doped mesoporous (45S5) bioactive glasses (BG) were synthesized by solgel technique and calcination without using polymers (porogens), mould or other additives. The phases and their functional groups were confirmed by the X-ray diffraction (XRD) and Fourier transform infrared (FTIR) and FTRaman spectroscopy respectively. Sodium calcium phosphate silicate [(Na0.11Ca0.89) (P0.11Si0.89O3)] which is essential for assisting the self-repair process of enamel was formed along with sodium calcium silicate (Na2Ca2Si3O9) phase. Doping of Sr ions (0.2 wt %) enhances the pore volume (96%) and surface area (108%) compared to pristine. Further, interconnected network structures are created exhibiting controlled and sustained drug release (58% in 720 h). The mechanical strength of the Sr doped BG samples increased significantly. The compressive strength of sample (Sr = 0.2 and 0.5 wt %) were 8.1 +/- 0.5 and 11.2 +/- 0.5 MPa with respective percentage increase of 440 and 647% compared to BG. The thermal stability and zeta potential of the Sr doped BG samples increase with considerable variation in the particle size when compared to the pristine. The cell viability and proliferation were also significantly enhanced by the doping of Sr ions which tailor the surface properties as well. The overall results robustly demonstrate for the first time that the very low doping of Sr ions (<= 0.2%) in BG, play a major role in engineering the properties viz., mechanical, surface, drug release and cell proliferation making them suitable for multifunctional biomedical applications.