TENACIOUS BINDING OF FIBRINOGEN AND ALBUMIN TO PYROLITE CARBON AND BIOMER

Adsorption of bovine fibrinogen from dilute plasma and human serum alb umin (HSA) from buffered HSA solution to low-temperature isotropic (LT I) pyrolytic carbon (Pyrolite) and polyetherurethane urea (Biomer) was measured. Whereas fibrinogen adsorption to Biomer passed through a ma ximum at intermediate plasma dilution(a typical Vroman peak), maximal adsorption to Pyrolite occurred from undiluted plasma; i.e., there was no Vroman effect. Protein elution by sodium dodecyl sulfate (SDS) sur factant was also measured. The amount of fibrinogen eluted from both s ubstrates by SDS was less when the protein was adsorbed from more dilu te plasma or eluted after 4 days postadsorptive residence time. Under all conditions, fibrinogen retention by Pyrolite was greater than that by Biomer. Binding of a monoclonal anti-fibrinogen (against residues 402-411 of the gamma chain) to substrates preadsorbed with human plasm a was measured using an ELISA. Antibody binding (normalized to the amo unt of fibrinogen adsorbed) to plasma preadsorbed Pyrolite was much le ss than that to preadsorbed Biomer. On both surfaces, normalized antib ody binding was much greater when fibrinogen adsorption had occurred f rom more dilute plasma. Monolayer adsorption of HSA to Pyrolite was ob served. HSA retention was greater when the protein was adsorbed from m ore dilute solution. These results demonstrate that proteins are tenac iously bound to Pyrolite compared with Biomer. Therefore, the thrombor esistance of Pyrolite may be partly due to the lowered reactivity of t he platelet binding domain, as well as a lessened ability of tightly b ound fibrinogen to interact with platelets. (C) 1996 Academic Press, I nc.