Preparation And Biocompatibility Of Novel Degradable Zn-Ge Alloy

Zinc?Zn?and its alloys have great potential in the field of biodegradable implant materials due to its unique combination of suitable biodegradability and good biological functionalities.However,the currently existing industrial Zn-based alloys have not sufficiently mechanical properties,such as low strength and poor plasticity,which significantly limit their further clinical application.Therefore,the improvement of mechanical properties is a critical scientific issue to be solved in the clinical application of zinc alloy.In this paper,Zn–xGe?x=1,3 and 5 wt.%?and Zn–3Ge–0.5X?X=Cu,Mg and Fe?alloys were developed via alloying and microstructure optimization,and its influence of alloy composition and processing technology on microstructure,mechanical properties,degradation behavior,in vitro hemocompatibility,and cytotoxicity were systematically assessed.The main contents and results are as follows:?1?A Zn–Ge binary degradable alloy system was designed and prepared with the alloying element of Ge,and its mechanical properties,degradation behavior,in vitro hemocompatibility,and cytotoxicity were evaluated.Microstructural characterization revealed that the Zn–Ge alloys are mainly composed of?–Zn phase and eutectic phase??–Zn and Ge phase?,and the Ge element has the effective grain-refining effect on Zn alloy.Tensile test results indicated that the hot-rolled Zn–5Ge alloy showed excellent mechanical properties with an ultimate tensile strength(?_UTS)of 237.0 MPa and an elongation???of 21.6%.The degradation rate of the Zn–Ge alloys decreased with the addition of Ge,and the as-cast Zn–5Ge has the lowest one.Zn–Ge alloys exhibited excellent in vitro hemocompatibility,and its enhanced hemocompatibility of pure Zn appeared with a proper amount of Ge addition.The diluted extract?concentration of 50%and 25%?of Zn–Ge alloy showed a higher cell activity than those of pure Zn.?2?Based on Zn–3Ge alloy,a Zn–3Ge–0.5X ternary alloys with excellent corrosion resistance and biocompatibility were designed and prepared via micro-alloying with the essential nutrients of Cu,Mg,and Fe.Microstructural characterization revealed that Zn–3Ge–0.5X alloys contained an?–Zn phase,eutectic Ge phase,and a small amount of irregular Mg₂Zn₁₁ and FeZn₁₃ phases at the?–Zn phase boundary.Tensile test results indicated that both the strength and hardness of hot-rolled Zn–3Ge alloy significantly improved after micro-alloying.The hot-rolled Zn–3Ge–0.5Mg alloy exhibited better yield strength among those alloys,high than 44.7%of that of the hot-rolled Zn-3Ge alloy.The degradation rate of as-cast alloys is lower than that of hot-rolled alloys after immersion in Hank's solution for one month,and the Zn–3Ge–0.5Fe alloy exhibited the lowest degradation rate.CCK–8 assay using MG63cells indicated that the diluted extracts of Zn–3Ge–0.5X alloys exhibited lower cytotoxicity,therein the Zn–3Ge–0.5Cu alloy showed a high cell survival rate of over90%,showing the best cytocompatibility.