The interfacial exchange processes between human serum albumin (HSA) and fibrinogen at different surfaces was investigated with in situ ellipsometry and TIRF. With ellipsometry, it was found that the total adsorbed amount at silica on addition of fibrinogen after preadsorption of HSA was quite similar to that obtained without HSA preadsorption. From TIRF, it is concluded that the preadsorbed HSA is displaced, although not completely, on addition of fibrinogen. On the other hand, preadsorbed HSA effectively blocked further adsorption of fibrinogen and IgG at hydrophobic surfaces such as methylated silica. Furthermore, the competitive adsorption of HSA and fibrinogen at two phospholipid surfaces, i e, phosphatidylcholine (PC) and phosphatidic acid (PA), was investigated. It was found that at PA, fibrinogen adsorbs extensively even after preadsorption of HSA. This, however, is achieved with essentially no displacement of the preadsorbed HSA. For PC, finally, the fibrinogen adsorption is much lower than that of HSA, and fibrinogen is able neither to coadsorb with HSA nor to displace the preadsorbed protein.
A954