Spraying-assisted layer-by-layer assembled coatings with dual self-healing ability to resist degradation and enhance endothelialization of ZE21B alloys for vascular stents

Drug-eluting magnesium (Mg) alloy stents have a slower degradation rate and lower restenosis rate compared with uncoated stents, demonstrating good clinical efficacy. However, the release of anti-hyperplasia drugs from coatings delays endothelial tissue repair, thus leading to late stent thrombosis. To address these issues, a dual self-healed coating with various biological properties was fabricated on magnesium fluoride/polydopamine (MgF₂/PDA)-treated Mg alloys by spraying-assisted layer-by-layer (LBL) self-assembly of chitosan (CS), gallic acid (GA), and 3-aminobenzeneboronic acid-modified hyaluronic acid (HA-ABBA). The LBL coating, approximately 1.50 μm thick, exhibited a uniform morphology with good adhesion strength (~ 1065 mN). The annual corrosion rate (P_i) of LBL samples was ~ 1400 times slower than that of the Mg substrate, due to the physical barrier function provided by MgF₂/PDA layers and the dual self-healed ability of LBL layers. The rapid self-healing ability (with a healing period of ~ 4 h under dynamic/static conditions) resulted from the synergistic interplay between the recombination of diverse chemical bonds within the LBL coating and the coordination of LBL-released GA with Mg²⁺, as corroborated by computer simulations. Compared with the drug-eluting coatings, the LBL sample demonstrated substantial advantages in anti-oxidation, anti-denaturation of fibrinogen, anti-platelet adhesion, anti-inflammation, anti-hyperplasia, and promoted-endothelialization. These benefits effectively address the limitations associated with drug-eluting coatings.

Graphical abstract