Drug-eluting stent with improved durability and controllability properties, obtained via electrocoated adhesive promotion layer

Drug-eluting stents (DES) have become an accepted technology in intravascular intervention. Manufacturing methodologies of DES are based mainly on mechanical processes, which tend to generate coatings that have poor stability properties; these were recently related as a potential hazard. A novel approach for significantly increasing the adhesion of polymer coatings onto DES is presented. The method is based on the electrochemistry of diazonium salts. These substances are organic compounds with the characteristic structure of R-N₂⁺ X^-, where R is an organic residue and X^- is an anion. The objective of this article is to study the properties of a selected diazonium salt 4-(1-dodecyloxy)-phenyldiazonium tetrafluoroborate, referred as C₁₂-phenyldiazonium. This material was found to be a superior adhesive promoter for polymeric coatings applied onto metallic stents. C₁₂-phenyldiazonium was synthesized and electrocoated on metallic stents and plates. The multilayer films of C ₁₂-phenyldiazonium were further characterized through electrochemical (cyclic voltammetry, impedance spectroscopy), physical (light and scanning electron microscopy, X-ray photoelectron spectroscopy, peeling tests), and chemical methodology (high pressure liquid chromatography). Further biocompatibility properties of the electrocoated basecoat were evaluated using in vitro and in vivo models. Synthesized C₁₂-phenyldiazonium was successfully electrocoated onto metallic surfaces. Electrochemical tests demonstrated its efficient and controllable electrocoating. C ₁₂-phenyldiazonium was found to increase polymeric coating stability as was reflected by a standard adhesion test. Electrocoated metallic stents spray-coated with a second polymeric film showed improved durability following incubation in physiological buffer. Furthermore, this improvement in durability exhibits stabilized drug release. In addition, biocompatibility evaluations have demonstrated basecoat's inert properties.