Dopamine and Lysine Modified Polyimide Fibers for Antithrombosis and Endothelialization Studies

Small-diameter vascular grafts (SDVGs, <6 mm) exhibit significant potential as alternatives to coronary and peripheral arteries, yet their clinical application is hindered by thrombosis and intimal hyperplasia. A synergistic modification strategy utilizing polydopamine (PDA) and lysine (Lys) was developed to functionalize polyimide (PI) fibers, aiming to enhance the antithrombotic properties and endothelial regeneration capacity of SDVGs. Alkaline etching activates PI fibers and facilitates the formation of PDA-Lys composite coatings through Schiff base and Michael addition reactions. Characterization results demonstrate that the modified fibers exhibit significantly reduced surface roughness and enhanced hydrophilicity, while retaining high mechanical strength and thermal stability. Hemocompatibility assessments reveal that PI-PDA-Lys fibers exhibit a hemolysis rate below 3.4% and an 80% reduction in platelet adhesion relative to unmodified fibers. This performance improvement is attributed to the optimized surface charge balance and reduced surface roughness. Human umbilical vein endothelial cells (HUVECs) show high viability, sustained proliferation over 7 days, and enhanced migration toward PI-PDA-Lys scaffolds. This multifaceted surface engineering strategy effectively addresses the critical challenges of thrombosis and delayed endothelialization in SDVGs. The modified PI fibers demonstrate significant potential to serve as a viable platform for the development of advanced small-diameter vascular grafts.