at later stages of the adsorption process proteins like high Competitive adsorption from a ternary mixture of human serum molecular weight kininogen dominated the adsorbed layer. albumin (HSA), human IgG, and human fibrinogen (Fgn) at con-This sequential adsorption is widely referred to as the Vrocentrations corresponding to blood plasma diluted 1/100 was inman effect and has been observed by others (8-10), alvestigated with the combination of Total Internal Reflection Fluothough systems behaving differently have also been obrescence spectroscopy (TIRF) and ellipsometry. As substrates, served (11, 12).
three different plasma polymer surfaces, representing different
Protein adsorption is known to be affected not only by surface charge and surface energy, were prepared from hexameththe properties of the solid surface, but also by those of the yldisiloxane (PP-HMDSO), acrylic acid (PP-AA), and 1,2-diaminocyclohexane (PP-DACH). In addition, adsorption from single protein itself and of the intervening solvent. Attempts have and binary protein systems was investigated with ellipsometry. At been made to find general rules for the interfacial behavior the hydrophobic PP-HMDSO little or no displacement of any of of ''soft' ' and ''hard'' proteins, i.e., proteins with low or the proteins was observed. The adsorbed layer was dominated by high conformational stability, respectively, and soft proteins HSA and IgG, although Fgn was also present to a smaller extent. are often found to adsorb more strongly than hard proteins On PP-DACH and PP-AA, representing positively and negatively at both hydrophobic and hydrophilic surfaces (13, 14). Furcharged hydrophilic surfaces, respectively, Fgn completely domithermore, the charge of the surface is believed to be an nated the adsorbed layer while HSA was almost absent and IgG important factor, although no general trends have been was present only at a very low level.