Biodegradable Zn–Cu–Li alloys with ultrahigh strength, ductility, antibacterial ability, cytocompatibility, and suitable degradation rate for potential bone-implant applications

Abstract

Zinc (Zn) and its alloys have promising potential application in biodegradable bone implants, attributable to their moderate degradation rate and biological safety in the human body. Nevertheless, the insufficient mechanical properties of pure Zn are challenging in meeting the mechanical property requirements for bone-implant materials. Here, we report the effects of alloying and hot rolling on the microstructure, mechanical properties, corrosion and degradation behavior, friction and wear performance, cytocompatibility, and antibacterial ability of Zn–2Cu–xLi (x ​= ​0, 0.4, and 0.8 ​wt%) alloys. Our results indicate that the hot-rolled (HR) Zn–2Cu–0.4Li alloy exhibited the best comprehensive set of mechanical properties with yield strength of 280.8 ​MPa, ultimate tensile strength of 394.6 ​MPa, and elongation of 62.2%. The corrosion rate of HR Zn–2Cu–xLi samples in Hanks’ solution increased with the increasing addition of Li and the HR Zn–2Cu–0.4Li alloy showed an appropriate corrosion performance with I_corr of 33.8 ​μA/cm², V_corr of 488 μm/a, and a degradation rate of 33 μm/a, making it suitable for bone-implant applications. The Zn–2Cu–xLi samples exhibited increased wear resistance with increasing Li addition. The diluted extracts of HR Zn–2Cu–xLi at 12.5% concentration exhibited non-cytotoxicity and the HR Zn–2Cu–0.4Li alloy showed the highest cell viability toward MG-63 ​cells. Further, the HR Zn–2Cu–0.4Li showed effective antibacterial ability toward S. aureus. Overall, the HR Zn–2Cu–0.4Li alloy can be considered a promising biodegradable metallic biomaterial for bone-implant applications.