A biodegradable in situ Zn-MgGe composite for bone-implant applications.

Zinc (Zn)-based composites have received extensive attention as promising biodegradable materials due to their unique combination of moderate biodegradability, biocompatibility, and functionality. Nevertheless, the low mechanical strength of as-cast Zn-based composites impedes their practical clinical application. Here we reported the mechanical properties, corrosion behavior, wear properties, and cytotoxicity of in situ synthesized biodegradable Zn-xMgGe (x = 1, 3, and 5 wt.%) composites for bone-implant applications. The mechanical properties of Zn-xMgGe composites were effectively improved by alloying and hot-rolling due to particle reinforcement of the MgGe intermetallic phase and dynamic recrystallization. The hot-rolled (HR) Zn-3MgGe composite exhibited the best mechanical properties, including a yield strength of 162.3 MPa, an ultimate tensile strength of 264.3 MPa, an elongation of 10.9%, and a Brinell hardness of 83.9 HB. With an increase in MgGe content, the corrosion and degradation rates of the HR Zn-xMgGe composites gradually increased, while their wear rate decreased and then increased in Hanks' solution. The diluted extract (12.5% concentration) of the HR Zn-3MgGe composite showed the highest cell viability compared to the other HR composites and their as-cast pure Zn counterparts. Overall, the HR Zn-3MgGe composite can be considered a promising biodegradable Zn-based composite for bone-implant applications. STATEMENT OF SIGNIFICANCE: This paper reports the mechanical properties, corrosion behavior, wear properties, and cytotoxicity of in situ synthesized biodegradable Zn-xMgGe (x = 1, 3, and 5 wt.%) composites for bone-implant applications. Our findings demonstrated that the mechanical properties of Zn-xMgGe composites were effectively improved by alloying and hot-rolling due to MgGe particle reinforcement and dynamic recrystallization. The hot-rolled Zn-3MgGe composite showed superior cytocompatibility, satisfying corrosion and degradation rates, and the best mechanical properties including a yield strength of 162.3 MPa, an ultimate tensile strength of 264.3 MPa, and an elongation of 10.9%.