Plasma fibrinogen, behavior

The adsorption experiments were carried out by quantifying each of proteins adsorbed on the material from mono-component protein solutions, from four-component protein solutions, and from plasma and diluted plasma. Adsorption profiles of protein were largely different, depending on the aforementioned experimental conditions. For instance, the behavior of any particular protein from diluted plasma varied in response to the extent of plasma dilution. Cooper s results are illustrated in Fig. 3, on fibrinogen adsorption onto five polymer surfaces. It is seen that the adsorption profiles are different one another, being influenced by the different nature of the polymer surfaces. The surface concentrations of adsorbed protein are mostly time-dependent, and maxima in the adsorption profiles were observed. This is interpreted in terms of replacement of adsorbed fibrinogen molecules by other proteins later in time (Vroman effect). Corresponding profiles were also presented for FN and VN. 

The Behavior of Albumin in Plasma at the Oxidized Silicon Surface. A chance for albumin to be adsorbed out of plasma, not yet encountered on any of the materials tested, could be provided by removing fibrinogen and some globulins from competition. Some normal intact plasma was... 

No surface was found on which plasma would deposit albumin preferentially, even though albumin is its most abundant component. The present study of heated plasma to which fibrinogen had then been added and of the behavior of albumin in presence of another protein suggests that in normal plasma there is something more than the sum of competing proteins that keeps albumin from being adsorbed. 

A concerted effort is presently needed to study the mechanisms influencing adsorption behavior in protein mixtures. Does adsorption from mixtures behave as the sum of independent adsorption events determined by specific affinity constants charactertistic of each species Can such a simple explanation suffice to explain the peak in adsorption isotherms seen for fibrinogen from plasma ("the Vroman effect") and also from binary mixtures (56,57) If the differences in adsorption behavior of mixtures compared to single adsorbates are better understood than at present, a greater degree of control of the adsorption process to achieve a desired end (e.g., selection of a desired protein) may be possible. For example, if the Vroman effect is a general feature of all protein mixtures, then clearly there is an optimum concentration for adsorption to achieve the greatest selectivity. 

The majority of hemocompatibility studies are performed under static conditions, but some groups considered the effect of flow on platelet adhesion in dynamic experiments. As one example, randomly structured PMMA surfaces with feature sizes of 40 nm, 80 nm, and 400 nm and heights of 3nm, 13 nm, and 50 nm were investigated under flow conditions [108,109], Experiments with human whole blood showed a preferred adsorption of vWF compared to that of fibrinogen and albumin, which is in conflict with other static studies. It is apparent that different adsorption behaviors of plasma proteins can be observed under different flow conditions. The platelet adhesion was highest on those samples with the most vWF adhesion, namely the larger structures. Experiments were carried out with washed platelets and revealed other results. Platelets preferred the smaller structured surfaces for adhesion, which shows the severe influence of blood cells and plasma proteins on the adhesion behavior of platelets [108]. 

Santerre JP, ten Hove P, VanderKamp NH, Brash JL. Effect of sulfonation of segmented polyurethanes on the transient adsorption of fibrinogen from plasma possible correlation with anticoagulant behavior. J Biomed Mater Res 1992 26(1 ) 39-57. 

Very little of the research that has been done on these proteins has involved the use of electrochemical techniques. Instead, ellipsometry, FTIR/ATR spectroscopy, radioactive labeling, and photon correlation spectroscopy have been used. Many of the studies have been directed toward the development of biocompatible polymer surfaces. The first event that takes place after contact of blood or plasma with an artificial surface is the rapid adsorption of proteins from the blood onto the material surface. It is generally assumed that all subsequent events, such as platelet adhesion and surface activation of blood coagulation, are determined by the composition and structure of the initially adsorbed protein layer. It is known from in vitro experiments that the adhesion of platelets is promoted when fibrinogen has been adsorbed on a material surface and that platelet adhesion is reduced when preadsorbed albumin is present on the surface. In a study of the adsorption behavior of three of the more abundant... 

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