Bioactive glass–gelatin hybrids: building scaffolds with enhanced calcium incorporation and controlled porosity for bone regeneration

Thanks to their active promotion of bone formation, bioactive glasses (BG) offer unique properties for bone regeneration, but their brittleness prevents them from being used in a wide range of applications. Combining BG with polymers into a true hybrid system is therefore an ideal solution to associate toughness from the polymer and stimulation of bone mineralization from the glass. In this work, we report the synthesis and characterization of hybrid scaffolds based on SiO2–CaO bioactive glass and gelatin, a hydrolyzed form of bone type-I collagen. Incorporation of calcium ions, known to trigger bone formation and cellular activity, into the hybrid structure was achieved at ambient temperature through careful control of chemistry of the sol–gel process. Thorough characterization of the materials highlights the effect of grafting an organoalkoxysilane coupling molecule to covalently link networks of BG and gelatin, and proves it a successful means to take control over the degradation and bioactive properties of hybrids. Importantly, BG–gelatin hybrids are synthesized in a process fully conducted at ambient temperature that allows obtaining open-porous scaffolding structures, with well-controlled and tuneable porosity with regards to both pore and interconnection sizes. Mechanical properties of the scaffolds under compression are similar to that of trabecular bone and their apatite-forming ability is even higher than that of pure BG scaffold foams.