EFFECT OF PROTEIN ADSORPTION ON THE BLOOD-CONTACTING RESPONSE OF SULFONATED POLYURETHANES

Polyurethanes which are grafted with propyl sulphonate functionality h ave excellent blood-contacting properties. In a canine ex vivo series shunt experiment, very low platelet deposition was observed on these m aterials and those platelets which were adherent remained unspread. In contrast to this, large amounts of fibrinogen, of the order of a mono layer or greater, were deposited on these surfaces in this ex vivo exp eriment. This led to the hypothesis that perhaps the deposited fibrino gen did not retain its platelet-adhesive activity. In this paper, we i nvestigate the possibility that these materials exert their antithromb otic effects through the adsorbed protein layer. Protein adsorption ki netics and isotherms on these sulphonated polyurethanes are determined . Multilayer protein adsorption or absorption into the hydrogel-like m aterials is found for each of the proteins studied, and the greatest a mounts of protein are seen on the most highly sulphonated polyurethane s. Further, the blood-contacting response of these materials is invest igated after pre-conditioning with either fibrinogen, fibronectin or a lbumin. When these materials are pre-adsorbed with either fibrinogen o r fibronectin, a very thrombogenic response was observed, which sugges ts that the platelet-adhesive activity of these proteins is not being reduced. Pre-adsorption of albumin did not improve the thromboresistan ce of these surfaces.