Controlled Release of Aspirin from SiO2-PEG Hybrid Coating on 316Lss Substrate for the Preparation of Drug Eluting Stents

Despite drug eluting stents (DESs) have revolutionized the interventional cardiology over the past decade since the first DES became commercially available nearly a decade ago, burst release of loaded drugs and late thrombosis caused by polymer coatings of the stents are high concerned. In this situation, inorganic coatings, such as silica-based hybrid materials, have aroused researcher's interest. In this study, aspirin (ASA) was incorporated into the sot-gel derived silica matrix with polyethylene glycol (PEG) as an organic modifier to improve the flexibility and extensibility of the inorganic matrices. We also used L-3,4-dihydroxyphenylalanine (L-DOPA) as a bio-adhesive reagent to enhance interface adhesion between the coating materials and the 316L stainless steel substrate. The results show that the introduction of D-LOPA can greatly improve the coating quality by enhancement of uniformity and adhesion. The loading ASA was slowly released from the coatings and burst release was effectively inhibited owing to the encapsulation of ASA molecules in the silica-PEG matrices.