One-step co-doping of ZnO and Zn^(2+)in osteoinductive calcium phosphate ceramics with synergistic antibacterial activity for regenerative repair of infected bone defect

How to endow bone grafts with long-term antibacterial activity and good bone regenerative ability to achieve the regenerative repair of infected bone defects has been the focus of the clinical treatment of osteomyelitis.The present study introduced a novel one-step route to realizing the co-doping of zinc oxide(ZnO)and zinc ion(Zn^(2+))in biphasic calcium phosphate(BCP)ceramics to utilize their synergistic antibacterial.Compared with the conventional BCP ceramics(BCP-Ca),the ZnO/Zn^(2+)co-doping ones(BCP-Zn)possessed strong antibacterial ability on E.coli and S.aureus as well as stimulated the osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs)effectively.The synergistic antibacterial mechanism of ZnO and Zn^(2+)was also investigated.BCP-Zn showed excellent osteoinductivity and angiogenesis at three months postoperatively in the canine intramuscular implantation model.Moreover,BCP-Zn exhibited excellent anti-infective ability and bone regenerative repair compared to BCP-Ca and control groups in the infected bone defect model of rat femur.Collectively,these findings suggest that the simultaneous introduction of ZnO/Zn^(2+)could have immense potential to expand the application of osteoinductive BCP ceramics in the regenerative repair of infected bone defects.

Strategies of strengthening mechanical properties in the osteoinductive calcium phosphate bioceramics

Calcium phosphate(CaP)bioceramics are widely applied in the bone repairing field attributing to their excellent biological properties,especially osteoinductivity.However,their applications in load-bearing or segmental bone defects are severely restricted by the poor mechanical properties.It is generally considered that it is challenging to improve mechanical and biological properties of CaP bioceramics simultaneously.Up to now,various strategies have been developed to enhance mechanical strengths of CaP ceramics,the achievements in recent researches need to be urgently summarized.In this review,the effective and current means of enhancing mechanical properties of CaP ceramics were comprehensively summarized from the perspectives of fine-grain strengthening,second phase strengthening,and sintering process optimization.What’s more,the further improvement of mechanical properties for CaP ceramics was prospectively proposed including heat treatment and biomimetic.Therefore,this review put forward the direction about how to compatibly improve mechanical properties of CaP ceramics,which can provide data and ideas for expanding the range of their clinical applications.