Current status and perspectives of zinc-based absorbable alloys for biomedical applications

Absorbable metals have the potential to serve as the next generation of temporary medical implant devices by safely dissolving in the human body upon vascular tissue healing and bone regeneration. Their implementation in the market could greatly reduce the need of costly and risky additional surgeries for either implant replacement or removal, often required in current permanent implants. Despite the extensive research done over the last two decades on magnesium (Mg) and iron (Fe) based alloys, they have not generally shown a satisfactory combination of mechanical properties, biocompatibility and controlled degradation rate in the physiological environment. Consequently, zinc (Zn) based alloys were introduced in the last few years as alternative materials to overcome the limitations of Fe and Mg-based alloys. The blend of different alloying elements and processing conditions have led to a wide variety of Zn-based alloys having tunable mechanical properties and corrosion rates. This review provides the most recent progress in the development of absorbable Zn-based alloys for biomedical implant applications, primarily for cardiovascular and orthopedic devices. Their biocompatibility, processability and metallurgical aspects, as well as their mechanical behavior and corrosion properties are presented and discussed, including their opportunities, limitations and future research directions.