From grain refinement to multifunctional balance: Tuning Zn content in binary Mg alloys for integrated biomedical...

Biodegradable magnesium (Mg) alloys hold great promise for next-generation implantable devices, but the inherent trade-offs among degradation control, mechanical integrity, and local biological responses hinder their clinical translation. Guided by the "material plainification" concept, which advocates avoiding complex alloy components, this work presents a systematic investigation of binary Mg-xZn alloys (x = 0.5-4 wt.%) processed by thermoplastic deformation, revealing the regulatory effects of zinc (Zn) content on dynamic recrystallization and the subsequent influences on overall biomedical performance. Results demonstrate that a moderate Zn content significantly promotes grain refinement and grain boundary (GB) stability. In particular, Mg-1.25Zn alloy emerges as the optimal "window", exhibiting a refined grain size of 2.7 μm and a balanced combination of mechanical properties (YS 258 MPa, UTS 280 MPa, EL 20.6 %). Besides, this alloy forms a protective corrosion product layer with a low in vitro corrosion rate of 0.11 mm·y⁻¹ and shows superior anti-inflammatory activity in a murine implantation model. Composed of bioessential elements and featuring compositional simplicity with potential cost advantages, the fine-grained Mg-1.25Zn alloy demonstrates a favorable balance among mechanical performance, degradation behavior, and biological response, thereby supporting its further development for soft tissue anastomosis and related biomedical applications. STATEMENT OF SIGNIFICANCE: Biodegradable magnesium alloys hold promise for next-generation implantable devices. However, balancing degradation rate, mechanical strength, and host response remains a key challenge for clinical translation. Guided by the concept of "material simplification", this study systematically investigates binary Mg-Zn alloys with Zn as the sole alloying element after thermo processing. By regulating Zn content, a composition-microstructure-property relationship is established, identifying Mg-1.25Zn as an optimal composition window. This alloy shows refined grains, favorable mechanical properties, a low in vitro corrosion rate, and anti-inflammatory activity in animal models, indicating that simple, low-cost binary alloys can achieve multifunctional performance optimization, thereby supporting its further development for soft tissue anastomosis, vascular occlusion, and related biomedical applications.