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.

Enhanced bone regenerative properties of calcium phosphate ceramic granules in rabbit posterolateral spinal fusion through a reduction of grain size

Osteoinductivity is a crucial factor to determine the success and efficiency of posterolateral spinal fusion(PLF)by employing calcium phosphate(Ca-P)bioceramics.In this study,three kinds of Ca-P ceramics with microscale to nanoscale gain size(BCP-control,BCP-micro and BCP-nano)were prepared and their physicochemical properties were characterized.BCP-nano had the spherical shape and nanoscale gain size,BCP-micro had the spherical shape and microscale gain size,and BCP-control(BAM®)had the irregular shape and microscale gain size.The obtained BCP-nano with specific nanotopography could well regulate in vitro protein adsorption and osteogenic differentiation of MC3T3 cells.In vivo rabbit PLF procedures further confirmed that nanotopography of BCP-nano might be responsible for the stronger bone regenerative ability comparing with BCP-micro and BCP-control.Collectedly,due to nanocrystal similarity with natural bone apatite,BCP-nano has excellent efficacy in guiding bone regeneration of PLF,and holds great potentials to become an alternative to standard bone grafts for future clinical applications.

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.