| Nowadays,the Mg-based alloys as the third generation biomedical materials have the many excellent advantages.Such as,perfect mechanical properties,biodegradable and cytocompatibility,and it has received much attention from scientific research institutions.However,the degradation rate of the Mg-based alloys is very fast,and the Mg-based alloys have poor biocompatibility,and so on.These defects have limited the clinical application in the bone issue engineer.The Mg-based amorphous alloy has a special structure,high strength and excellent corrosion resistance,it has attracted widespread attention in the world.Because,after the alloy was degraded in the body,the elements of the Mg-Zn-Ca amorphous alloy could be absorbed by human tissues,and these Mg2+,Zn2+,Ca2+are essential elements for human body,it is demonstrate that the Mg-Zn-Ca amorphous alloy have perfect biocompatibility.Therefore,the Mg-Zn-Ca amorphous alloys have broad application prospects as novel biomedical materials.In this paper,the Mg68-Zn28-Ca4 amorphous alloys were prepared in a vacuum melting furnace by copper mold injection.The Ca-P pretreatment layer which have good biocompatibility was prepared on the substrate of the Mg68-Zn28-Ca4 amorphous alloy by a hydrothermal method.Then,the coating of nHA/PCL composite was coated on the pre-treatment layer by dip-coating technique.Finally,the double-layered nHA and nHA/PCL composite coating were prepared on the substrate of the Mg68-Zn28-Ca4 amorphous alloys,the double-layered nHA and nHA/PCL composite coating can improve the corrosion resistance and biocompatibility of the Mg68-Zn28-Ca4 amorphous alloys.During the preparation of the double-layered coating,the microstructure of the double-layered coating and amorphous were obtained by the environmental electron scanning microscope(SEM),the composite of the products and amorphous were obtained by the X-ray diffractometer(XRD).The corrosion resistance and biocompatibility of the double-layered coating samples were analyzed with the electrochemical test,immersion test and cell co-culture,cell attachment,animal implantation experiments.The above experimental results have demonstrated that the corrosion resistance and biocompatibility of the Mg68-Zn28-Ca4 amorphous alloys were significantly enhanced with double-layered coating.The density of the Ca-P pre-treatment layer is getting worse with the pH of the solution is increasing during the preparing.It is indicate that the alkaline solution has a certain inhibition effect on the formation of the pre-treatment layer.While the content of nHA is 0%,The porosity the surface is the lowest,and the pore size is 0.5 μm.With the increase of nHA content,the porosity of the surface is increasing and the pore size is also increasing during the preparing.When the nHA content is increased to 8%,the porosity of the surface is the largest,and the pore size is 4 μm.It is show that the porosity of the surface and the diameter of the pore were increased with the content of the nHA in nHA/PCL composites coating.Therefore,the degradation rate of the composite material can be controlled by controlling the content of the nHA in the nHA/PCL composite coating.The cell co-culture and cell attachment experiments have demonstrated that the biocompatibility of the Mg-Zn-Ca amorphous alloys were significantly improved with the double-layered coating.And the Mg-Zn-Ca amorphous alloys which were coated with the 2%nHA/PCL composite coating have the best biocompatibility.Subsequently,the implantation experiment have confirmed that the Mg-Zn-Ca amorphous alloys which were coated with the 2%nHA/PCL composite coating could be completely degraded within a certain time in the animal body,and the damaged bone tissue were completely healed within a certain time.In summary,the above experiments have demonstrated that the Mg-Zn-Ca amorphous alloys which were coated with the 2%nHA/PCL composite coating can be used as a potential degradable biomaterial for the bone issue engineering. |
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