| In clinical application,due to the absorption atrophy of alveolar bone after tooth loss,periodontal disease,tumor,trauma and other factors,the amount of alveolar bone in the horizontal and vertical directions is insufficient,which to a large extent limits the application of implant restoration.Guided bone regeneration technology(GBR)is currently an effective method for the treatment of alveolar bone deficiency,in which biological barrier membrane plays a very important role.Its comprehensive properties,such as mechanical strength,degradation rate and biocompatibility,are the main factors affecting the safety of treatment and the effectiveness of osteogenesis.The elastic modulus of commonly used non-absorbable biofilms is greatly different from that of human bones,which will produce "stress shielding effect".However,the mechanical properties of absorbable biofilms are poor and it is difficult to guarantee the space for osteogenesis.Therefore,biodegradable metal biofilms have attracted more and more attention from scholars.Magnesium alloy is expected to replace the traditional biological barrier membrane due to its mechanical properties close to human bone,unique degradability and good biocompatibility.However,the degradation rate of magnesium alloy is difficult to match with the healing rate of human bone and its mechanical properties need to be further improved,which limits its wide application.Purpose:In this paper,Mg-Zn-Ca alloys with different calcium contents were prepared by semi-continuous casting method,and their microstructure,mechanical properties,corrosion resistance and biocompatibility were detected and analyzed to provide theoretical basis for subsequent in vivo experiments and clinical studies.Methods:Four kinds of Mg-Zn alloy materials with different calcium content were prepared by semi-continuous casting method.The microstructure,mechanical properties and corrosion properties of the prepared Mg-Zn alloy were detected by SEM observation,XRD phase composition,tensile test and electrochemical corrosion experiment.Then,the biocompatibility and osteogenic potential of the four magnesium alloys were studied by in vitro cell experiments,including CCK-8,live and dead cells staining,cells adhesion,alkaline phosphatase(ALP)staining and activity detection,and Western blot.Results:1.Through microstructure and mechanical properties tests,it is found that Mg-4Zn-0.5Ca alloy shows the best mechanical properties,with yield strength reaching 261 MPa and tensile strength reaching 300 MPa.2.Through the analysis of the electrochemical polarization curves of four kinds of Mg-Zn-Ca alloys,it was found that the corrosion rates of the four kinds of Mg-Zn-Ca alloys were not significantly different in Hank’s simulated body fluids.3.The biological behavior of MC3T3-E1 cells was tested by using the alloy or its extracts.It was found that all the four alloys were non-toxic and could promote the proliferation of MC3T3-E1 cells,revealing that the magnesium alloy had good biocompatibility in vitro.The results of ALP staining and ALP activity test showed that magnesium alloy had the potential to promote the osteogenic differentiation of MC3T3-E1 cells.Western blotting assay showed that Mg-4Zn-0.5Ca alloy could promote the expression of BMP-2,Col-1 and OCN osteogenic standard protein in MC3T3-E1 cells.Mg-4Zn-0.5Ca had the most obvious effects on the proliferation,adhesion and protein expression of MC3T3-E1 cells in Mg alloys with different Ca contents.Conclusion:Mg-4Zn-0.5Ca material has good mechanical properties,suitable corrosion rate,excellent biocompatibility and excellent osteogenic potential.This study provides a theoretical basis for magnesium alloy in vivo experiments and clinical studies.Mg-4Zn-0.5Ca magnesium alloy is expected to be a new medical bone implant material. |
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