PREFERENTIAL ADSORPTION OF PLASMA-PROTEINS ONTO APOLAR POLYURETHANE MICRODOMAINS

Adsorbed proteins mediate interactions between synthetic biomaterials and physiologic environments. Segmented polyurethane elastomers are extensively used in biomedical devices such as catheters, blood pump bladders, and vascular grafts. Microphase separation in these materials has been correlated with biocompatibility, however, whether separate microdomains exist at aqueous polyurethane surfaces is unknown. Using high-voltage transmission and low-voltage scanning electron microscopy, 10-30 nm soft segment microdomains were imaged at the surface of a hydrated polybutadiene-polyurethane, within the nanometer level surface sensitivity of the instrumentation. Subsequently, two different colloidal gold labeling techniques were used to determine if the distribution of fibronectin, fibrinogen, and albumin, adsorbed from single protein solutions, were influenced by the microdomain morphology. Both immunogold labeling and a novel technique of labeling with unconjugated colloidal gold, which provides very high spatial precision, showed that all three proteins preferentially adsorb to the apolar polybutadiene soft segment microdomains. Thus, protein adsorption is influenced by surface microenvironments of comparable size to the protein itself. This suggests that the phase-separated microstructure of polyurethanes may organize the biological-material interface. © 1990.