Adsorbed protein layer, organization

Adsorbed proteins can greatly influence cellular reactions with synthetic materials. The sensitivity to adsorbed proteins, the variation in cellular response to specific proteins, and the rapid adsorption of proteins to all surfaces exposed to the biological environment, have led to the idea that the cellular response to implanted polymers is the result of specific interactions between components of the adsorbed protein layer on the polymer and the cell periphery. These observations, in turn, have led to the hypothesis that cellular interactions with foreign materials are controlled by the presence at the surface of specific proteins at sufficiently high surface density and degree of reactivity to elicit a response. Each of these factors constitutes an important aspect of the organization of the adsorbed protein layer. 

The organization of the adsorbed protein layer is influenced by differences in the surface activity of proteins, competition in mixtures, and complex displacement kinetics. 

The important material properties which can influence protein and cell interactions at the biomaterial-biologic interface are listed in Table 2. It is probable that surface composition and topography most strongly influence the composition and organization of the initial adsorbed protein layer It is this layer which mediates subsequent cellular events at that interface. Thus, a great deal of effort has gone into surface modifications and characterization of polymeric biomaterials. 

One of the most challenging issues in this application is the adsorption of proteins on both inorganic and organic membranes. This leads to fouling which in turn limits the membrane flux as shown in Table 6.3 [Quemeneur and Jaouen, 1991]. The hydraulic resistance due to the layer of the adsorbed protein, R, can be significant when compared... 

The usefulness of XPS to study layers obtained by adsorption of nfixed protein solutions is limited since different proteins in the adsorbed layers can usually not be distinguished. However, XPS may still bring some information regarding the organization (thickness, surface coverage) of these mixed protein layers. This can be coupled to the information brought by other techniques in view of obtaining a detailed description of the adsorbed layer. 

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