Poly-ε-caprolactone/polysulfhydrylated polyester blend: A platform for topical and degradable nitric oxide-releasing materials

Abstract

Polymeric biomaterials for implantable medical devices are subject to demands that go beyond passive biocompatibility. Inhibition of thrombus formation, reduced inflammatory response and the eventual complete bioabsorption of the implant are central challenges for emerging polymeric biomaterials. Nitric oxide (NO) released at the biomaterial/tissue interface may inhibit platelet adhesion and improve tissue integration in blood-contacting/implanted devices. In addition, local NO release may increase vasodilation, thereby improving ischemic conditions in topical applications. In this study, we present a novel degradable NO-releasing polymeric platform based on blended poly-ε-caprolactone (PCL)/polysulfhydrylated polyester (PSPE). PCL formed miscible blends with PSPE up to 45 wt% of PSPE. S-nitrosation of the PCL/PSPE blends converted the surface PSPE component into a NO-releasing polynitrosated polyester (PNPE). Real-time chemiluminescence NO detection showed that blends with different PCL:PSPE ratios allow surface S-nitrosothiol concentrations in the range of 0.5–1.5 μmol/cm2. Topical application of blended PCL/PNPE films on the healthy skin led to a 6–10-fold increase in the skin blood flow due to local NO delivery, as shown by in vivo laser-Doppler flowmetry. Blended PCL/PSPE films displayed higher hydrophilicity and a 2–11-fold increase in the hydrolytic mass loss, compared to pure PCL films. Therefore, PCL/PSPE blend is a potential biomaterial platform for local NO delivery and more quickly degradable biomedical devices.