Protein onto polymer surfaces, adsorption

On the other hand, the values for g13 or g23 are positive, with a few exceptions. In other words, the adsorption processes of water and of protein onto polymer surfaces are for the most part thermodynamically unfavorable. The negative values of gs are the result of a remarkable decrease in free energy when adsorptive water molecules are driven back to the bulk water system, as seen... 

Adsorption of Blood Proteins onto Polymer Surfaces... 

A Ithough the adsorption of polymers onto solid surfaces has been thor-oughly studied (I), relatively few studies can be found in the literature on the adsorption of proteins onto polymer surfaces. In 1905, Landsteiner and Uhliz (2) discussed the interaction of serum proteins with synthetic surfaces. Blitz and Steiner (3) showed that albumin adsorption onto solid surfaces increased with increasing albumin concentration and that adsorption was nearly irreversible. Hitchcock reported (4) that adsorption of egg albumin onto collodion membranes followed a Langmuir isotherm with maximum adsorption occurring near the isoelectric point. Later, Kemp and Rideal (5) reported that protein adsorption onto solids conforms with Langmuir adsorption. 

R. G. Lee, S.W. Kim, Adsorption of protein onto hydrophobic polymer surfaces adsorption isotherms and kinetics, J. Biomed. Mater. Res. 8 (1974) 251-259. 

Protein Adsorption. The development of medical implant polymers has stimulated interest in the use of ATR techniques for monitoring the kinetics of adsorption of proteins involved in thrombogenesis onto polymer surfaces. Such studies employ optical accessories in which an aqueous protein solution (93) or even ex - vivo whole blood (94-%) can be flowed over the surface of the internal reflection element (IRE), which may be coated with a thin layer of the experimental polymer. Modem FT-IR spectrometers are rapid - scanning devices, and hence spectra of the protein layer adsorbed onto the IRE can be computed from a series of inteiferograms recorded continuously in time, yielding ah effective time resolution of as little as 0.8 s early in the kinetic runs. Such capability is important because of the rapid changes in the composition of the adsorbed protein layers which can occur in the first several minutes (97). 

To attain this goal, we used ATR techniques which have been described previously (6). A liquid ATR cell can be used to circulate protein solutions (or blood) through the cell while spectrally monitoring the adsorption of proteins onto the surface of the ATR crystal. In addition, the ATR crystal can be coated with a thin layer of polymer, permitting us to follow the adsorption of pro-... 

The relative extent of protein adsorption onto polymer surfaces is influenced by the surface tensions of the substrate material, of the suspending liquid and of the proteins themselves. For one and the same substrate material the extent of protein adsorption depends on the relative hydrophobic ty of the proteins. For the situation where YlV > YPV more hydrophobic proteins will adsorb to the largest extent. 

Holmberg M, Hou XL (2010) Competitive protein adsorption of albumin and immunoglobulin G from human serum onto polymer surfaces. Langmuir 26 938-942... 

The following protocol for passive adsorption is based on methods reported for use with hydrophobic polymeric particles, such as polystyrene latex beads or copolymers of the same. Other polymer particle types also may be used in this process, provided they have the necessary hydrophobic character to promote adsorption. For particular proteins, conditions may need to be optimized to take into consideration maximal protein stability and activity after adsorption. Some proteins may undergo extensive denaturation after immobilization onto hydrophobic surfaces therefore, covalent methods of coupling onto more hydrophilic particle surfaces may be a better choice for maintaining native protein structure and long-term stability. 

A change in the environment of a protein molecule, e.g. adsorption from aqueous solution onto a sorbent surface, may lead to a partial breakdown of its ordered structure, resulting in an increase of conformational entropy. This is a fundamental difference between protein adsorption and the adsorption of flexible polymers, for which attachment to a surface implies a loss of conformational entropy. 

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. 

There is good evidence that proteins adsorbed from solutions onto some solid surfaces form films in which the molecules remain predominantly in the compact configuration, are unoriented at the interface (6, 7), or may not unfold at liquid/solid interfaces (8). Protein adsorption onto synthetic polymer surfaces is important because of its possible... 

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