Design, synthesis, and characterization of polymer-hydrogel composite vascular grafts using double-expanded polytetrafluoroethylene to achieve enhanced mechanical and biological properties

Expanded polytetrafluoroethylene (ePTFE) is commonly used for vascular grafts. However, its application as small-diameter grafts has been hampered due to problems such as thrombosis and restenosis stemming from mismatched mechanical properties and lack of endothelialization. As an effort to fabricate vascular grafts with mechanical properties akin to natural blood vessels, an extra expansion step in the fabrication of ePTFE was introduced that led to a more compliant double-expanded PTFE (dePTFE). Further, a layer of P(AAm-co-NaAMPS)-xanthan-alginate hydrogel was synthesized and mechanically interlocked onto the luminal surface of dePTFE vascular grafts. In this novel synergistic approach, the outer polymer layer provided mechanical support while the inner hydrogel layer enhanced cytocompatibility, endothelialization, and burst pressure resistance. Among the four types of vascular grafts studied, namely, ePTFE, dePTFE, ePTFE-P(AAm-co-NaAMPS)-xanthan-alginate, and dePTFE-P(AAm-co-NaAMPS)-xanthan-alginate, the last hydrogel vascular graft exhibited the most desirable attributes. It had the highest longitudinal and circumferential tensile strengths with a desirable "toe region," highest burst and leakage pressures, and highest suture retention strength. Additionally, this vascular graft also demonstrated the best endothelialization capabilities. Overall, the dePTFE-P(AAm-co-NaAMPS)-xanthan-alginate hydrogel vascular graft was found to be a promising candidate for PTFE-based vascular grafts, showing potential for future applications in vascular graft transplantation.Highlights Mechanical interlocking ensures robust bonding of hydrogel and dePTFE grafts. Hydrogel-enhanced cytocompatibility, endothelialization, and burst pressure resistance. dePTFE-hydrogel graft showed better properties and endothelialization capability.