Fabrication and characterization of heparin-immobilized electrospun nanofibers for vascular suture applications

One of the most significant complications of vascular surgery is thrombosis, which is the formation of blood clots at the surgical site. Another significant complication is stenosis - an overgrowth of cells during the healing process, which narrows the same artery the surgeons were trying to open. These complications often lead to additional surgeries and carry increased morbidity and mortality for the patients. Numerous pharmaceutical agents have been tested to prevent these complications, but the results have been disappointing. The agents either have unacceptable systemic effects, or they cannot achieve a controlled, timed release in the circulation. Heparin is the most commonly used anti-coagulant for anastomotic thrombosis prevention, with numerous studies employing heparin-immobilized or heparin-coated biomaterials for improved thrombo-resistance.;In this study, the feasibility of heparin-immobilized electrospun nanofibers as surgical sutures was explored. Using a novel positively charged amphiphilic copolymer as well as PLGA and PEO, fibers were successfully prepared via electrospinning and twisted into uniform yarns. The yarns were characterized using FE-SEM and tensile testing. Fluorescein conjugated heparin was surface immobilized on the yarns through electrostatic interactions, and released out from the nanofibers. The therapeutic activity of the immobilized heparin was tested in vitro also. It was shown that the heparin loading efficiency was greatest in the yarn containing the highest weight percent of the positively charged PEI polymer and the release kinetics were more gradual and controlled compared to control yarns. Further work needs to be done to improve the mechanical properties of the yarns to make them acceptable for commercial use.