Unraveling the synergistic effects of Ag, Li and Sr on Zn alloys in enhancing orthopedic repair potential

Recently, Li, which can greatly enhance the mechanical characteristics of zinc alloys, Ag, which has antibacterial properties, and Sr, which promotes bone formation, have been widely applied in biodegradable alloys. However, to our knowledge, there has been no research on the combined effects of Ag, Li, and Sr in zinc alloys. To address this, we have created a new quaternary alloy (Zn–3Ag–0.1Li–0.1Sr). The incorporation of Ag, Li, and Sr increased the yield strength (YS) of the at-cast (AC) zinc alloy to 188.83 ± 12.38 MPa. After extrusion and hot rolling, the strong plasticity of the alloy was further significantly enhanced, with ultimate tensile strength (UTS) exceeding 400 MPa, YS exceeding 350 MPa, and elongation (EL) greater than 50%. An in vitro cell study revealed that after three days of culture with a 50% extract, the proliferation rate of MC3T3-E1 cells was 101.527 ± 0.129%, and the cells maintained a healthy spindle-shaped appearance. The antibacterial experiments also demonstrated that the Zn–3Ag–0.1Li–0.1Sr quaternary alloy has strong antibacterial properties against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Therefore, the biodegradable Zn–3Ag–0.1Li–0.1Sr quaternary alloy, which exhibits high strength, good cytocompatibility, and satisfactory antibacterial performance, has greater potential for application in the field of orthopedic repair.