Comparative mechanical characterisation of 13–93 bioactive glass and hybrid scaffolds for bone regeneration

Biomaterial bone scaffolds offer a promising alternative to traditional treatments. Bioactive glass has shown promise however its clinical application is limited by its poor mechanical properties. Flexible hybrids are a potential solution. Herein, previous studies incorporated calcium into a silica/poly(tetrahydrofuran)/poly(ε-caprolactone) (SiO₂/PTHF/PCL-diCOOH) sol-gel hybrid to enhance its mechanical performance. We firstly compared these material scaffolds to 13–93 bioactive glass (13–93 BG) (54.6% SiO2, 22.1% CaO, 6.0% Na2O, 7.7% MgO, 7.9% K2O, and 1.7% P2O5, in mol%) scaffolds. We reveal that the hybrid material exhibits a randomised porous microstructure and superior mechanical deformability, whereas the 13–93 BG scaffolds remain stiffer and more brittle. Micro-computed tomography (µCT) quantification reveals that the glass scaffolds underwent less shrinkage after direct ink writing (DIW) than the hybrid scaffolds, enabling easier reproduction of the design files. We demonstrate that the hybrid scaffold can withstand strains of up to 7%, mimicking the elastic behaviour of bone, while the 13–93 BG scaffold fails at 2% strain. Finite element (FE) analysis revealed a more decentralized stress distribution and higher local strain within the hybrid scaffold, whereas the 13–93 BG scaffold showed high stress concentration at strut junctions in line with a higher risk of brittle failure. The characterisation methods applied in this study can be extended to other biomaterials, providing valuable insights for biomaterials research and guiding scaffold design for bone regeneration.