Macromolecular surface films at a solid/liquid interface

Macromolecules generally adsorb well to a solid/liquid interface but do not produce more than a monolayer of molecules in cases where the molecules are reasonably soluble in the liquid medium. This is because for second or higher layer adsorption, the interaction would have to be between segments of macromolecules in solution and segments of macromolecules on the surfaces. Such interactions between segments of soluble macromolecules in solution do not, however, lead to adhesions. Some of the segments of surface held macromolecules would have to have been altered in their reactivity in order that second and, progressively, multilayer formation could occur. This is not too hard to accept in the case where the adsorbing macromolecule is a protein. A decline of reactivity with layer number could be a factor in limiting the growth of the surface multilayer or gel. The presence of a weakly elastic gel at the boundary with a flowing suspension will strongly influence the flow pattern in its vicinity. Effectively flow is slowed down and could essentially be stopped even without having to seal off the vessel totally. It is thus possible to conceive of mechanisms by which an endoendothelial fibrin layer is not only built up but would also function as proposed by Copley.