Degradation behavior and biological properties of a novel biodegradable zinc alloy biliary stent

Current biodegradable biliary stents remain inadequate for clinical demands. Zinc (Zn) alloys, exhibiting excellent mechanical properties, moderate degradation rates, and favorable biocompatibility, are potential materials for biodegradable biliary stents. In this study, trace boron (B) was added to Zn-0.8Cu alloy to enhance its mechanical properties and biocompatibility, and to investigate its suitability as biliary stent. The incorporation of 0.03 wt% boron significantly refined the grain size and introduced the bimodal organization, consequently enhancing the mechanical properties of Zn-0.8Cu alloy (As cast: yield strength, ultimate tensile strength, and elongation increased by 52.0 %, 42.5 %, and 153.8 %, respectively). Moreover, boron addition reduced the corrosion resistance of Zn-0.8Cu alloy and the surface became hydrophilic (water contact angle 70.75° ± 1.74°). In vitro evaluations revealed that the Zn-0.8Cu-0.03B alloy exhibited excellent biocompatibility and strongly inhibited the growth of Staphylococcus aureus and Escherichia coli. Finally, the Zn-0.8Cu-0.03B alloy stents maintained structural integrity in the rabbit common bile duct for 3 weeks, followed by accelerated degradation, and were completely degraded within 8 weeks. Zn-0.8Cu-0.03B alloy stents showed excellent biocompatibility in vivo, the degradation products were safely eliminated without causing biliary stricture or obstruction, and tissue hyperplasia induced by stent was effectively alleviated. In conclusion, this study expands the applications potential of Zn alloy in biomedicine and provides reference for developing new generation biodegradable biliary stents.