Alloying design of biodegradable zinc as promising bone implants for load-bearing applications

By Hongtao Yang, Bo Jia, Zechuan Zhang, Xinhua Qu, Guannan Li, Wenjiao Lin, Donghui Zhu, K. Dai, Yufeng Zheng. Nature Communications, 2020

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Magnesium-based biodegradable metals (BMs) as bone implants have better mechanical properties than biodegradable polymers, yet their strength is roughly less than 350 MPa. In this work, binary Zn alloys with alloying elements Mg, Ca, Sr, Li, Mn, Fe, Cu, and Ag respectively, are screened systemically by in vitro and in vivo studies. Li exhibits the most effective strengthening role in Zn, followed by Mg. Alloying leads to accelerated degradation, but adequate mechanical integrity can be expected for Zn alloys when considering bone fracture healing. Adding elements Mg, Ca, Sr and Li into Zn can improve the cytocompatibility, osteogenesis, and osseointegration. Further optimization of the ternary Zn-Li alloy system results in Zn-0.8Li-0.4Mg alloy with the ultimate tensile strength 646.69 ± 12.79 MPa and Zn-0.8Li-0.8Mn alloy with elongation 103.27 ± 20%. In summary, biocompatible Zn-based BMs with strength close to pure Ti are promising candidates in orthopedics for load-bearing applications. Biodegradable implants are of great interest in orthopaedic applications but have been limited by low mechanical strength. Here, the authors examine systematically in detail the strengthening of biodegradable zinc by alloying with beneficial elements using mechanical, biodegradability and biocompatibility testing.

Subfields: Biomaterials, Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/24ca875f80e51768d7b02feb076be33c3203215c