Adsorption kinetics of protein mixtures. A tentative explanation of the Vroman effect.

A model for protein adsorption kinetics has been presented. This model includes diffusion-limited adsorption, adsorption and desorption rate constants kon and koff, which are dependent on the surface concentration, and an interaction term for the mutual influence of the adsorbed protein molecules. It has been shown that, in first approximation, values of kon and koff are exponential functions of the surface concentration. Assuming an adequate interaction term, it is possible to show with this model for a mixture of proteins that the ratio of the absorbed proteins is strongly dependent on the overall surface concentration even if the ratio of the bulk concentrations of these proteins is kept constant. Differences in interaction terms for the different proteins offer a possible explanation for the peculiar behavior of plasma protein adsorption on a surface at different dilutions of the plasma, the so-called Vroman effect.