Strontium-doped calcium silicate scaffolds with enhanced mechanical properties and tunable biodegradability fabricated by vat photopolymerization

 Strontium-doped calcium silicate (SrCS) bioceramics have demonstrated outstanding vasculogenic ability to repair large segmental bone defects, while their poor mechanical properties and rapid degradation rate remain the major obstacles in clinical treatment. Here, we proposed a novel approach to significantly enhance the mechanical properties of SrCS bioceramics with tunable biodegradability using micron barium titanate-based (BTA) powders as a dopant. Biomimetic SrCS-BTA scaffolds with triply periodic minimal surface structures were fabricated by vat photopolymerization. The effects of BTA content on microtopography, mechanical properties, degradability, and bioactivity of composite scaffolds were studied. On the one hand, the BTA greatly increased the maximum densification rate of SrCS ceramics by 84.37%, while the corresponding densification temperature decreased by 95°C. On the other hand, CaTiO3 generated by the reaction of SrCS and BTA intercepted cracks at the grain boundaries, and thus, the mechanical properties were enhanced due to the pinning effect. The SrCS-40BTA scaffold exhibited much higher compressive strength and elastic modulus by 296% compared with the pure SrCS scaffold. The energy absorption of SrCS-40BTA scaffolds was 5.6 times higher than that of the pure SrCS scaffold. In addition, biocompatible SrCS-BTA scaffolds with lower degradation rates can play a supporting role in the process of repair for a longer duration. This work provides a promising strategy to fabricate biomimetic scaffolds with highly enhanced mechanical properties and tunable biodegradability for repairing damaged large segmental bone tissues.