Electrospun Heparin-Loaded PCL Nanofiber Sutures with Sustained Release for Antithrombotic Applications

Background/Objectives: Conventional surgical sutures can promote local coagulation after implantation, potentially compromising vascular patency. Heparin is an effective anticoagulant, but systemic administration may cause bleeding and thrombocytopenia. This study aimed to develop an electrospun heparin-loaded polycaprolactone (PCL) suture that combines structural support with sustained local heparin delivery and antithrombotic activity. Methods: Heparin was incorporated into electrospun PCL sutures at nominal heparin-to-PCL feed ratios of 0.05 and 0.50 wt%. Fiber morphology, chemical characteristics, tensile properties, heparin release, molecular interactions, cytocompatibility, hemolysis, and plasma recalcification were evaluated. Molecular dynamics simulations were used to investigate PCL-heparin interactions. In vivo antithrombotic performance was assessed in a liver puncture model using male C57BL/6 mice, followed by histological examination. Results: Heparin incorporation preserved the fibrous morphology of the sutures, although maximum tensile stress and strain were modestly reduced compared with PCL alone. Both heparin-loaded formulations exhibited sustained heparin release over 10 days, and molecular dynamics simulations indicated stable PCL-heparin interactions. Cell viability did not differ significantly among the suture groups, and all hemolysis rates remained below 5%. In the plasma recalcification assay, both heparin-loaded groups remained incompletely coagulated at 300 s, indicating marked anticoagulant activity. In the mouse liver injury model, heparin-loaded sutures reduced local clot formation compared with PCL sutures. Conclusions: Electrospun heparin-loaded PCL sutures integrate sustained local heparin delivery with in vitro anticoagulant and in vivo antithrombotic activity. These findings support further evaluation of this multifunctional suture platform in clinically relevant vascular models.