Optimization of the CaO and P₂O₅ contents on PDMS–SiO₂–CaO–P₂O₅ hybrids intended for bone regeneration

Osteoproductive materials that induce quick bone regeneration are needed for the developing area of scaffold-based bone engineering. Bioactive silica-based glasses, ceramics, and hybrids are called to play an important role in this field. Organic–inorganic hybrid materials based on SiO₂-modified PDMS–P₂O₅–CaO are studied in this work. These materials are synthesized by the sol–gel method, and the influence of the composition on the reaction kinetic, obtained porosities, degradation and bioactive behavior, and cytotoxicity is studied. Materials with greater contents in CaO yield faster reaction kinetics and produce porous materials that favor a quicker degradation, whereas with greater P₂O₅ contents produce denser and more stable materials. The incorporation of CaO and P₂O₅ up to 5 and 25 % in weight into the SiO₂ network, respectively, resulted in an increase of the apatite-forming ability in PBS. None of the studied compositions are cytotoxic, showing cellular viability over 70 % at all times.