ABSTRACT

The alteration of the polymer's biocompatibility by the controlled variation of the ratio between monomers was also shown for an albumin-polysiloxane carbonate system (see Table 7; Fig. 29). The results illustrate the expected effect of the siloxane fraction of the copolymer on the quantity of irreversibly adsorbed protein. The most considerable effect is that for which the ratio of copolymer components has on the reversible adsorption kinetics. The larger extent of structural rearrangement in proteins stimulates protein-protein interactions. This intensifies the reversible adsorption and increases the equilibrium constant of the reversible layer. Once this opposite effect of structural rearrangement on kinetics of adsorption exists, an optimal ratio of monomers should be expected from the point of polymer biocompatibility. For in vitro conditions, this optimal ratio should be expected at values of 50 : 50 for polysiloxane carbonate and 60 : 40 for polyetherurethane.