Core-shell Zn/P-doped calcium silicate bioceramics with spatiotemporally regulated degradation and high-efficient oesteogensis for emergent bone trauma repair

Ca-silicate (CSi) bioceramics have garnered significant interest in bone tissue engineering but their multifunction and biodegradation are suboptimal for some emergent bone trauma conditions. Foreign ion doping and core-shell architectural design offer promising strategies to optimize osteogenic efficacy while precisely regulating degradation kinetics and biologically functional ion release. Herein we developed the core-shell porous bioceramics via coaxial nozzle system, featuring a P-doping wollastonite (CSi-P) core and Zn-doping wollastonite (CSi-Zn)/β-tricalcium phosphate (β-TCP) shells. A 10% porogens in the shell layer would enable controllable micropore architecture. In vitro studies demonstrated that Zn doping could finely tune the CSi-shell degradation rates, governing both physical dissolution and sustained release of bioactive ions. The CSi-based components further exhibited superior biomimetic remineralization capability in simulated body fluid. Meanwhile, both P12@Zn8 and P12@Zn12 exhibited remarkable antibacterial potential against Gram-positive bacteria (S. aureus). In vivo mandibular defect experiments revealed that the CSi-Zn granules outperformed β-TCP counterparts in bone repair at 10 and 16 weeks interval. Notably, the P12@Zn8 formulation achieved optimal degradation-osteogenesis coupling, exhibiting enhanced trabecular bone formation and complete repair within 16 weeks. This core-shell design strategically balances tunable degradation with spatiotemporal bioactivity, and may provide a solution to the problem of matching the absorption time of the materials with the bone regeneration time in clinical practice. Our findings highlight the potential of compositionally graded core-shell bioceramics as next-generation bioactive implants for emergent bone trauma regeneration and repair.