Chitosan/heparin layer-by-layer coatings for improving thromboresistance of polyurethane

• Polyurethane (PU) plates are activated using hexamethylenediisocyanate. • Activated PU plates are modified with multilayer coatings of chitosan and heparin. • PU activation and modification are confirmed by FTIR, AFM, contact angle measurement. • Hemocompatible polymer coatings on the polyurethane surface do not provoke blood clots. The surface of polyurethane plates was activated using hexamethylenediisocyanate in the presence of a dibutyltin dilaurate catalyst. The presence of isocyanate groups was confirmed by FTIR spectroscopy. Polyelectrolytes chitosan and heparin were applied layer-by-layer to the activated polyurethane plates surface. The morphology of the plates surface at all stages of modification was studied using atomic force microscopy and scanning electron microscopy. An increase in the hydrophilic properties of the surfaces of modified polyurethane plates is confirmed by a decrease in the value of water contact angle. Modification of the polyurethane plates resulted in increased clotting time and recalcification time in vitro in the human blood. Thromboresistance of polyurethane plates during incubation in in vitro experiments for 20, 40, 120, 240 min reached 83,94±8,12% - 86,22±5,29%. The degree of hemolysis in vitro was insignificant and did not exceed 0.01%.