Platelet adhesion to novel phospholipid materials: Modified phosphatidylcholine covalently immobilized to silica, polypropylene, and PTFE materials

Based on the premise of achieving blood compatibility through mimicking the chemical constituents of the biologically inert surface of the unactivated platelet membrane, a process was developed that entails the covalent grafting of modified phosphatidylcholine molecules to materials including silica, polypropylene, and polytetrafluoroethylene (PTFE) polymer films. These materials were characterized using x-ray photoelectron spectroscopy (XPS) and contact-angle measurements. The phosphatidylcholine- containing materials (PC materials) were used as substrates in the platelet- adhesion assays and were subjected to enzymatic degradation evaluation. Phosphatidylcholine-grafted silica materials do not support platelet adhesion. In addition the number of adherent platelets correlate with the amount of grafted phospholipid present, as indicated by the phosphorus/carbon ratio obtained by XPS analysis. Platelet adhesion to phosphatidylcholine- grafted polypropylene and PTFE was inhibited 80% and 90%, respectively, when compared with platelet adhesion to unmodified polypropylene and PTFE.