Drug-Eluting Coronary Stents Coated with Polysulfone-Poly(ethylene Oxide) Block Copolymer by Ultrasonic Spray

Amphiphilic polysulfone-poly(ethylene oxide) block copolymers (PSF-b-PEOs) with different contents of PEO, have been successfully synthesized and employed as the drug carrier for use in drug-eluting stent (DES) systems. They are well soluble in organic solvents such as tetrahydrofuran (THF). Cell growth, hemolysis, cell hyperplasia, toxicity and sensitization tests revealed that PSF-b-PEOs have good biocompatibility. Silolimus was selected as the drug and the loading level was controlled at 10 or 20 wt%. PSF-b-PEO-coated stents were fabricated by the widely used ultrasonic spray coating technique. Pre- and post-expansion morphologies of the coatings were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Under the optimal operation conditions, the stents have uniform and smooth coating surface. No cracks or peels were observed when the coating stents were expanded. No drug particles were observed on the stent surface. PEO content in PSF-b-PEOs greatly influences drug release rate, and the higher the PEO content, the faster the release rate. PSF-b-PEO film comprising 30% PEO displayed relatively reasonable drug release rate, i.e., about 80% silolimus were released from the film after release tests in phosphate buffer solutions (PH = 7.4) containing 10 v% ethanol at 37 °C for 24 days.