Optimizing silicon doping levels for enhanced osteogenic and angiogenic properties of 3D-printed biphasic calcium phosphate scaffolds: An in vitro screening and in vivo validation study

Biphasic calcium phosphate (BCP) ceramics are valued for their osteoconductive properties but have limited osteogenic and angiogenic activities, which restricts their clinical utility in bone defect repair. Silicon doping has emerged as an effective strategy to enhance these biological functions of BCP. However, the biological impact of BCP is influenced by the level of silicon doping, necessitating determination of the optimal concentration to maximize efficacy in bone repair. This study investigated the effects of silicon doping on both the physicochemical and biological properties of BCP, with a specific focus on osteogenic and angiogenic potentials. Results indicated that silicon doping exceeding 4 mol.% led to the formation of α-TCP, accelerating BCP degradation, enhancing silicon ion release, and promoting mineralization product formation. Simultaneously, silicon doping increased the porosity of BCP scaffolds, which typically reduces their compressive strength. Nevertheless, scaffolds doped with ≤4 mol.% silicon maintained compressive strengths exceeding 2 MPa.