PHYSICOCHEMICAL PROPERTIES AND PLATELET INTERACTIONS OF SEGMENTED POLYURETHANES CONTAINING SULFONATE GROUPS IN THE HARD SEGMENT

The adhesion of platelets to a series of segmented polyurethanes havin g sulfonate groups in the hard segment is reported. The polyurethanes were synthesized using sulfonated chain extenders of different structu re. Analogous control materials without sulfonate groups also were stu died. Adhesion was measured in vitro using washed human platelets in a carrier fluid consisting of Tyrode's buffer with apyrase, albumin, an d red cells at normal concentration. The polymers were characterized b y gel permeation chromatography and elemental analysis. Water absorpti on and thermal transitions also were determined. It was found that the sulfonated materials absorb significant amounts of water while the no nsulfonated analogs do not. The surfaces of polymer films were charact erized by water contact angle and XPS. The contact angles of the sulfo nated surfaces were relatively low. Platelet adhesion to the sulfonate d polymers was found to be very high compared to the nonsulfonate anal ogs. The local environment of the sulfonate groups (different chain ex tenders) also appears to have an effect on platelet interactions. Albu min adsorption was high on all the materials and was not correlated wi th platelet adhesion. It appears from this work that platelets may hav e a binding site that is specific for sulfonate groups. (C) 1997 John Wiley & Sons, Inc.