Surface Modification of Polyurethanes with Covalent Immobilization of Heparin

摘要

Thrombus formation and blood coagulation is a major problem associatedwith blood contacting products such as catheters, vascular grafts, arteries, artificialhearts and heart valves. An intense research is being conducted towards the synthesisof new hemocompatible materials and modifications of surfaces with biologicalmolecules. In this study, polyurethane (PU) films were synthesized in medical purityfrom diisocyanate and polyol without using any other ingredients and their surfaceswere modified by covalent immobilization of heparin. Two types of heparin,unfractionated (UFH) and low molecular weight heparin (LMWH), were immobilizedto investigate their effect on cell adhesion. The surface properties of the modified PUswere examined with ESCA, ATR-FTIR and AFM. ESCA results demonstrated sulfur peaksindicating the presence of heparin and AFM results showed the alteration of surfacestructure after coating with heparin. Cell adhesion studies were conducted withheparinized whole human blood. The surfaces of the UFH immobilized films resultedin lesser red blood cell adhesion in comparison to LMWH demonstrating strong anti-thrombogenic activity of the latter.