Development of a Novel Magnesium Alloy with High Degradation Resistance and Osteo/Angiogenesis Activity Through Scandium-enhanced Growth of Passivation Film

Abstract

Addressing the challenge of balancing rapid degradation and insufficient bio-regenerative capabilities in biodegradable magnesium (Mg) alloys for bone repair is a significant endeavor. In this study, the influence of Scandium (Sc) content on the microstructure, strength, degradation, cytotoxicity, angiogenesis, and osteogenesis of Mg-4Yttrium(Y)-xSc alloy system is investigated, and a novel alloy Mg-4Y-2.25Sc (wt.%) that significantly inhibits degradation and promotes bone regeneration is successfully developed. This achievement is contributed to the combination of the alloying and high-temperature oxidation (HTO) treatment, guided by a thermodynamic calculation model. The performance of the alloy notably surpasses that of the widely used biodegradable WE43 alloy. At the microstructural level, a thin and dense protective film of Y₂O₃/Sc₂O₃ is introduced to form a passivation effect. The synergetic release of Mg and Sc ions significantly promotes angiogenesis and osteogenesis. In vivo results verify that Mg-4Y-2.25Sc implants promote osseointegration of implants during the bone healing cycle. In summary, the alloying system treated by HTO effectively modulates the degradation rate of Mg alloys without complex surface modification, providing a promising bone-repairing material for successful implantation.