Nanoarchitectonics of Pro-Degradative Coating to Enhance Iron Corrosion Behavior and Biosafety for Bioresorbable Cardiovascular Stents

Controlling both the resorption rate and the formation of reactive oxygen species (ROS) of biodegradable iron (Fe) remains a central challenge for the fabrication of bioresorbable cardiovascular stents. Here, we introduce an innovative nanoengineered surface coating strategy to simultaneously accelerate Fe corrosion and suppress ROS generation without altering the bulk Fe materials. Aryl-diazonium salt chemistry (4-cyanobenzene diazonium tetrafluoroborate, DCN) was used to create robust polyaryl interphases that can immobilize gold nanoparticles (Au NPs) on Fe, establishing nanoscale microgalvanic and catalytic sites. Electrochemical analysis reveals that the coating increases the overall Fe corrosion rate while biasing the cathodic oxygen reduction reaction toward the four-electron pathway, thereby reducing peroxide/OH^• formation. This mechanism is supported by the remarkably reduced OH^• content detected by the terephthalate-probe assay. Corrosion metrics show a pronounced, controllable rate enhancement relative to bare Fe, and the postcorrosion exposure interfacial spectroscopy/microscopy verify the persistence of Au NPs, attributed to atomic Fe-FeO-Au interactions and anchoring by the DCN-derived polyaryl layer. Endothelial cell culture indicates favorable adhesion and viability, supporting cytocompatibility of the modified surface. This surface-chemistry-driven mechanism establishes a general interfacial principle for rate and pathway control of Fe biodegradation, offering a concise route to safer, faster resorbing Fe-based stents.