Extruded biodegradable Zn-5Cu alloys with integrated osteoimmunomodulatory, antibacterial, and anti-osteolytic properties for patellar fracture suture repair

Zn-based biodegradable alloys hold promise for fracture suture-line applications, but are often limited by insufficient mechanical performance. In this study, alloying and extrusion were employed to regulate the microstructure of Zn-5Cu alloys, thereby synergistically optimizing their mechanical properties, corrosion behavior, and biological functions. Samples extruded at 200 °C exhibited the most favorable comprehensive mechanical performance, achieving a tensile yield strength of 191.5 MPa, an ultimate tensile strength of 208.3 MPa, and an elongation of 39.2%. After 28 days of immersion in simulated body fluid, the samples extruded at 200 °C showed the slowest degradation rate of 31.8 μm·y -1 . Notably, the extruded Zn-5Cu alloys exhibit better antibacterial performance than that of pure Zn due to the release of Cu 2+ . In vitro biological evaluations confirmed suitable cytocompatibility with negligible cytotoxicity. The extruded Zn-5Cu alloys also exhibited a pronounced ability to induce M2 macrophage polarization, thereby promoting osteogenesis and inhibiting osteoclast differentiation in vitro. In vivo studies confirmed the alloy’s osteoimmunomodulatory and anti-osteolytic functions. Collectively, these findings indicate that these extruded Zn-5Cu alloys with suitable degradation rates, enhanced mechanical properties, and integrated antibacterial, immunomodulatory, and osteogenic capabilities represent a promising material for fracture suture lines. Statement of Significance Biodegradable zinc alloys have shown promise for fracture fixation, yet their clinical translation remains hindered by insufficient ductility, uncontrolled degradation, and limited biological functionality. Here, we demonstrate that low-temperature extrusion of a Zn-5Cu alloy uniquely orchestrates immunomodulatory, antibacterial, and anti-osteolytic functions within a single material platform—a triad rarely achieved together. Through microstructure tailoring at 200 °C, our alloy achieves clinically suitable mechanical strength (191.5 MPa) and degradation rate (0.032 mm/y) while harnessing Cu 2+ release to promote M2 macrophage polarization, enhance osteogenesis, and suppress osteoclast differentiation. For readers, this work establishes a processing‑microstructure‑function paradigm for designing bioactive biodegradable metals that transcend passive fixation toward actively orchestrating bone regeneration.