Mechanical And Biological Properties Of Zn Or/and Fe Added Ca₅?PO₄?₂SiO₄ Bioceramics

Calcium phosphate silicate biomaterials have been widely studied as bone repair biomaterials owing to their good biocompatibility and osteogenic activity.Ideal materials for orthopedic clinic should have not only a good osteogenic activity,but also a good mechanical strength to provide an initial support.In this dissertation,silicocarnotite?Ca₅?PO₄?₂Si O₄,CPS?with good osteogenic activity has been taken as the research object,zinc?Zn?and iron?Fe?,the most abundant trace elements in human body,have been selected as the additive elements to promote the mechanical property and further enhance the biological property of CPS bioceramic.The regulation and related mechanism of the addition of Zn,Fe and Zn/Fe on mechanical property,degradation property and osteogenic activity of CPS bioceramic have been investigated.In addition,the effects of Zn and Fe on protein adsorption behavior of CPS bioceramic have been studied using proteomics technology.The main results obtained are described as follows:?1?Preparation and properties of Zn-CPS bioceramicsZn-CPS bioceramics with different ZnO contents were prepared using ZnO asadditive.The results showed that the addition of ZnO could significantly enhance the mechanical strength of CPS bioceramic,Zn-CPS bioceramic with 1 wt.%ZnO addition sintered at 1300°C exhibited a highest bending strength of 80.8 MPa,which was nearly2-times of that of pure CPS ceramic.Furthermore,Zn-CPS bioceramics could promote the proliferation and differentiation of r BMSCs cells,and exhibited antibacterial activities with the addition of ZnO.In vivo animal experiments showed that the osteogenic ability of Zn-CPS bioceramics increased with the augment of ZnO content,and promoted the degradation of CPS bioceramic.12 weeks after implantation,Zn-CPS bioceramic with 5 wt.%ZnO exhibited a highest osteogenic rate of 43.0%,and its degradation rate could up to 50.9%.?2?Preparation and properties of Fe-CPS bioceramicsFe-CPS bioceramics with different Fe₂O₃ contents were prepared using Fe₂O₃ as additive.The results showed that the addition of Fe₂O₃ could greatly improve the mechanical strength of CPS bioceramic,Fe-CPS bioceramic with 1.5 wt.%Fe₂O₃addition sintered at 1250°C exhibited a highest bending strength of 91.9 MPa,which was more than 2-times of that of pure CPS ceramic.Moreover,Fe-CPS bioceramics could promote the differentiation and mineralization of r BMSCs cells,and retained the good ability on apatite formation immersing in simulated body fluid.In vivo animal experiments showed that Fe-CPS bioceramics had good osteogenic activities,and 1Fe-CPS bioceramic exhibited a best capacity on promoting bone regeneration.12 weeks after implantation,1Fe-CPS bioceramic exhibited a highest osteogenic rate of 45.1%.?3?Preparation and properties of Zn/Fe-CPS bioceramicZn/Fe-CPS bioceramic with good comprehensive property was prepared adding ZnO and Fe₂O₃ as co-additives.The results showed that the addition of ZnO and Fe₂O₃ could significantly enhance the mechanical strength of CPS bioceramic,Zn/Fe-CPS bioceramic sintered at 1250?exhibited a highest bending strength of 83.3 MPa,which was more than 2-times of that of pure CPS ceramic.Under the synergistic effect of Zn and Fe elements,Zn/Fe-CPS bioceramic showed better apatite formation ability and in vitro degradation ability than Zn-CPS bioceramic,and it was more favorable for the proliferation and adhesion of r BMSCs cells.?4?Protein adsorption behavior of Zn-CPS and Fe-CPS bioceramicsThe effects of ZnO or Fe₂O₃ on the protein adsorption behavior of CPS bioceramic were investigated using proteomics technology.The results showed that the addition of ZnO or Fe₂O₃ significantly affected the protein adsorption behavior of CPS bioceramic.Mass spectrometry analyses presented that the types and amount of adsorbed proteins on CPS bioceramic surface evidently changed after the addition of ZnO or Fe₂O₃,and the addition of ZnO or Fe₂O₃ could help mediate cell adhesion on CPS bioceramic by activating focal adhesion pathway,ECM-receptor interaction pathway,regulation of actin cytoskeleton,rap1 signaling pathway and PI3K-Akt signaling pathway.Moreover,the protein adsorption results indicated that the addition of ZnO or Fe₂O₃ could increase the adsorption of cartilage-related proteins and angiogenesis-related proteins on CPS bioceramic.These proteins not only could promote cell adhesion through activating related pathways,but also may endow better abilities of CPS bioceramic on cartilage formation and vascularization.