The polydopamine‐assisted heparin anchor enhances the hydrophilicity, hemocompatibility, and biocompatibility of polyurethane

Abstract Surface heparinization is an effective solution to resolve low endothelialization, poor anticoagulation, and hemocompatibility of polyurethane (PU) used as materials of small‐diameter vascular grafts. Here, the effects of polydopamine (PDA) and poly (acrylic acid) (PAA) as crosslinking agents on the surface heparinization were explored. The PU membranes grafted with heparin (Hep) via dopamine (PU/PDA‐Hep) showed better hydrophilicity and stability, compared to heparinized PU membranes via acrylic acid (PU/PAA‐Hep). The results of X‐ray photoelectron spectroscopy demonstrated that heparin was successfully grafted onto the PU surface and the grafting efficiency was high when PDA as a cross‐linking agent. The grafted heparin aggregated and formed nanoparticles, and increased the surface roughness of PU membranes. The heparinized membranes demonstrated good anti‐adhesion of bovine serum albumin and fibrin protein. In addition, no activated platelets or educts on heparinized PU were found by platelet adhesion tests, implying that heparin‐immobilized surfaces had good hemocompatibility. Moreover, the in vitro cytocompatibility assessment showed that the PU/PDA‐Hep significantly improved the proliferation of L929 cells and was superior to PU/AA‐Hep. These results demonstrated that PDA‐assisted surface heparinization was an effective method to improve the anticoagulant and biocompatibility of PU small‐diameter vascular materials and could be extended to other implantable materials.