Boosting corrosion resistance and osteogenic activity of magnesium-based implants with metal ions chelated silk fibroin coating via binary solvent system

[Display omitted] •An innovative method has been developed for creating metal ion-chelated silk fibroin coatings using a binary-solvent system.•Increased β-sheet content (45.4%) and crystallinity in silk fibroin result in enhanced corrosion resistance.•A universal mechanism for stepwise nucleation induced by binary solvent has been proposed.•The chelation of Ca2+ and Sr2+ into silk fibroin facilitates controlled release, thereby enhancing osteogenic activity. The development of biofunctional coating is vital for the clinical application of implants. A persistent challenge with magnesium alloys implants, which are inherently prone to rapid degradation, is the simultaneously enhancement of corrosion resistance and bioactivity. This study introduces a novel protein coating for magnesium alloys, incorporating calcium and strontium ions with silk fibroin. By utilizing the microcrystal nucleation facilitated by a binary solvent system, the β-sheet content is significantly increased to 45.4 % in silk fibroin. The increased β-sheet bolsters the “labyrinth effect” at the nanoscale, resulting in a substantial improvement in corrosion resistance. This is evidenced by a three-order-of-magnitude reduction in the corrosion current density (Icorr) to 3.65 × 10−7 A cm−2, compared to that of the uncoated alloys. The meticulous doping of Ca2+ and Sr2+ ions ensures stable chelation with amorphous segments of silk fibroin. The controlled release activates the Wnt signaling pathway, boosting osteogenic activity. Such silk fibroin coating system, prepared through a straightforward method, enables a concurrent enhancement of both corrosion resistance and osteogenic potential in biomedical magnesium alloys.