Synergistic Effect of Strontium Doping and Surfactant Addition in Mesoporous Bioactive Glass for Enhanced Osteogenic Bioactivity and Advanced Bone Regeneration

Mesoporous bioactive glass (MBG) is an advanced biomaterial widely recognized for its application in bone regenerative engineering. This study synthesized an MBG powder (80 mol% SiO₂, 5 mol% P₂O₅, and 15 mol% CaO) using a facile sol-gel method with the non-ionic surfactant Pluronic^® P123, which acted as a pore-forming agent. MBGs form bioactive surfaces that facilitate HA formation, and the presence of Pluronic^® P123 increases the surface area and promotes HA nucleation. Various percentages of strontium (Sr) doping were examined to improve bioreactivity, biological response, and bone formation, with 3SMBG (3 mol% Sr) showing the highest specific surface area. In vitro biocompatibility tests revealed HA formation on all glass surfaces after immersion in simulated body fluid (SBF), indicated by sheet-like HA morphologies, the presence of PO₄³⁻ and CO₃²⁻ functional groups, and the amorphous structure along with SrCO₃ crystalline phases corresponding to HA and Sr-HA structures. Sr doping resulted in delayed initial degradation and sustained release of Sr²⁺, achieving over 95% cell viability. Surfactant-induced mesoporous structure and Sr incorporation synergistically enhance osteocyte induction and formation in vitro. These findings suggest that Sr-doped MBG, particularly with P123-assisted Sr/Ca substitution, optimizes the material’s properties for advanced bone regenerative applications.