Development of biodegradable zein-based bilayer coatings for drug-eluting stents

Drug-eluting stents (DES) have been widely used for the treatment of cardiovascular diseases. Nevertheless,chronic inflammation and delayed re-endothelialization still represent challenges for their clinical use. Inthe present work, we developed novel bilayer coatings for stent applications that could overcome theselimitations, exclusively using biodegradable plant-based drugs and polymers. In particular, stainless steelsurfaces were coated with rutin-loaded zein (the active layer) and cross-linked alginate (the sacrificiallayer) via facile dip and spray coating methods. Various mechanical tests and analysis tools, such asinfrared spectroscopy, water contact angle measurements, and scanning electron microscopy were usedto characterize the coated surfaces. Degradation and release studies of the films were extensively carriedout and compared. The release rate of rutin from the bilayer coating reached 66.1 3.2% within 24hours of incubation (initial burst period), while the rest of the drug was released over 21 days ina sustained manner. Antioxidant assays confirmed that rutin retained its free radical scavenging abilityafter being eluted in phosphate buffer at 37 C. In vitro results with human fibroblasts and endothelialcells suggested that the coating materials and their degradation products are highly biocompatible. Inconclusion, our novel drug-eluting coatings, fabricated with natural biodegradable polymers, arepromising materials for DES applications, allowing a sustained drug delivery and improving thebiocompatibility of cardiovascular implanted devices.