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Magnesium (Mg) and its alloys have been suggested as revolutionary biodegradable materials. However, fast degradation hinders its clinic application. To improve the corrosion resistance and biocompatibility of Mg-Nd-Zn-Zr alloy (JDBM), magnesium-aluminum-layered double hydroxide (Mg-Al LDH) was successfully introduced into Mg(OH) coating by hydrothermal treatment. The anions in the interlayer of Mg-Al LDH can be replaced by chloride ions, resulting in a relatively low chloride ion concentration near the surface of the coating. The favorable corrosion resistance of the coating was proved by polarization curves and hydrogen collection test. The Mg-Al LDH significantly promoted cell adhesion, migration and proliferation in vitro. In addition, the coating almost fulfilled the request of the clinical application in the hemolysis ratio test. Finally, in vivo results indicated that the coating offered the greatest long-lasting protection from corrosion and triggered the mildest inflammation comparing to the pure Mg(OH) coatings and untreated magnesium alloy. Mg(OH) coating containing Mg-Al LDH in the present study shows a promising application in improving anticorrosion and biocompatibility of Mg alloys, and might act as a platform for a further modification of Mg alloys ascribed to its special layer structure.

We report a Mg alloy Mg-2.2Nd-0.1Zn-0.4Zr (wt.%, denoted as JDBM-2) showing great potential in clinical vascular stent application by integrating the advantages of traditional medical stainless steel and polymer. This alloy exhibits high yield strength and elongation of 276 ± 6 MPa and 34.3 ± 3.4% respectively. The JDBM-2 with a stable degradation surface results in a highly homogeneous degradation mechanism and long-term structural and mechanical durability. In vitro cytotoxicity test of the Mg extract via human vascular endothelial cells (HUVECs) indicates that the corrosion products are well tolerated by the tested cells and potentially negligible toxic effect on arterial vessel walls. This alloy also exhibits compromised foreign body response (FBR) determined by human peripheral blood derived macrophage adhesion, foreign body giant cell (FBGC) formation and inflammatory cytokine and chemokine secretion. Finally, vascular stents manufactured from the JDBM-2 were implanted into rabbits for long-term evaluation. The results confirm excellent tissue compatibility and up to 6-month structural and mechanical integrity of the stent in vivo. Thus, the JDBM-2 stent with up to 6-month structural and mechanical integrity and excellent tissue compatibility represents a major breakthrough in this field and a promising alternative to traditional medical stainless steel and polymer for the clinical application.