Roles of micro-alloyed Y and Gd in improving the corrosion resistance and mechanical properties of pure Mg.

The microstructure, corrosion resistance and mechanical properties of extruded pure Mg, Mg-2Y and Mg-2Gd were studied by means of scanning electron microscope (SEM), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), scanning probe microscope (SPM), immersion test, electrochemical test and tensile test. The results demonstrated that Mg-2Y and Mg-2Gd were composed of Mg, Mg24Y5, and Mg5Gd phases with the addition of Y and Gd. The addition of Y and Gd to pure Mg noticeably reduced the grain size and textural strength of the alloy. Mg-2Gd alloy had the smallest grain size and the lowest textural strength. The corrosion rate of Mg-2Gd was the slowest due to the influence of grain size. Y slowed the corrosion of pure Mg in the early stages due to the grain refinement, but speeded up the corrosion because of the galvanic corrosion produced by the precipitation of the second phase in the latter stages. The elongation of pure Mg, Mg-2Y, and Mg-2Gd were 16.5 %, 38.67 %, and 48.67 %, respectively. The inclusion of Y and Gd refined the grain, softened the texture strength, and activated basal slip, which improved the elasticity of alloys. Gd was more significant than Y in improving the corrosion resistance and mechanical properties of pure Mg.

An oxidized dextran-composite self-healing coated magnesium scaffold reduces apoptosis to induce bone regeneration.

Self-healing coatings have shown promise in controlling the degradation of scaffolds and addressing coating detachment issues. However, developing a self-healing coating for magnesium (Mg) possessing multiple biological functions in infectious environments remains a significant challenge. In this study, a self-healing coating was developed for magnesium scaffolds using oxidized dextran (OD), 3-aminopropyltriethoxysilane (APTES), and nano-hydroxyapatite (nHA) doped micro-arc oxidation (MHA), named OD-MHA/Mg. The results demonstrated that the OD-MHA coating effectively addresses coating detachment issues and controls the degradation of Mg in an infectious environment through self-healing mechanisms. Furthermore, the OD-MHA/Mg scaffold exhibits antibacterial, antioxidant, and anti-apoptotic properties, it also promotes bone repair by upregulating the expression of osteogenesis genes and proteins. The findings of this study indicate that the OD-MHA coated Mg scaffold possessing multiple biological functions presents a promising approach for addressing infectious bone defects. Additionally, the study showcases the potential of polysaccharides with multiple biological functions in facilitating tissue healing even in challenging environments.