Rare-Earth modified biodegradable Zn alloys with high strength and enhanced osteogenesis

Achieving high strength and robust osteogenesis simultaneously remains a challenge for biodegradable orthopedic materials. Here we show that incorporating trace rare-earth (RE) elements into a Zn-Li-Mn system bridges this gap. By forming REZn_11-13 intermetallic phases, we engineer a bimodal grain structure that elevates tensile strength to 772 MPa and bending strength to 1207 MPa, approaching the level of medical-grade titanium alloy (Ti-6Al-4V) while retaining biodegradability. Crucially, these phases act as "potential-buffering" electrodes, ensuring uniform degradation and controlled zinc ion release. This optimized ion concentration activates the Rap1 signaling pathway, resulting in twofold greater bone regeneration compared to titanium alloy implants. By integrating ultrahigh mechanical strength with potent bioactivity, this Zn-Li-Mn-Y alloy provides a superior platform for next-generation load-bearing implants, offering a degradable alternative to permanent metallic fixations.