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

Abstract

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 Znbased BMs with strength close to pure Ti are promising candidates in orthopedics for loadbearing applications.

Recent research and progress of biodegradable zinc alloys and composites for biomedical applications: Biomechanical and biocorrosion perspectives

“…The increase in Li content from 0.2 to 0.7 at.% simultaneously improved the σ YS and σ UTS from 240 to 480 MPa and 360–560 MPa, respectively, yet their ductility was found relatively lower than the benchmark value of elongation for stent materials (20%). In a recent study, excellent mechanical strength and ductility of hot extruded Zn-xLi (x = 0.1, 0.4, 0.8) alloys with addition of Mn from 0.1 to 0.8 wt% were reported by Yang et al [ 213 ]. Their reported values of σ TYS , σ UTS and ε for all the binary and ternary alloys were well above the benchmark values for any vascular stent materials as shown in Table 5 .…”

Is There a Role for Absorbable Metals in Surgery? A Systematic Review and Meta-Analysis of Mg/Mg Alloy Based Implants

“…In vitro and in vivo investigations have been performed and have led to improvements in the biocompatibility, bone healing properties, and corrosion resistance of the absorbable metals [ 24 , 25 , 26 ]. The Zn-based alloys have been investigated, primarily due to their excellent electrochemical process [ 21 , 27 ], which does not result in the accumulation of gas cavities such as hydrogen [ 28 ]. Both metals have shown excellent biocompatibility during the degradation process.…”

“…Both metals have shown excellent biocompatibility during the degradation process. They were both safely metabolized, including simulation for osteoblastogenesis in bone surgeries [ 28 , 29 ]. However, pure Zn does not have enough mechanical properties for osteosynthesis materials for use in bone fracture fixation.…”

“…However, pure Zn does not have enough mechanical properties for osteosynthesis materials for use in bone fracture fixation. The primary element used to increase its strength is copper (Cu), which results in a suitable alloy for use (ZnCu) [ 18 , 28 ]. However, it is no longer an absorbable metal [ 30 ].…”

Development of Novel Lightweight Metastable Metal–(Metal + Ceramic) Composites Using a New Powder Metallurgy Approach

“…Similar to Zn being an excellent choice of alloying element to Mg, Mg is also a promising alloying element to Zn [ 16 ]. From the previous investigations [ 17 , 18 , 19 ], Zn-Mg alloys exhibit good corrosion resistance, enabling them to be promising candidates for implant applications.…”