AN EXPERIMENTAL-STUDY OF THE SURFACE RHEOLOGY OF ADSORBED PROTEIN LAYERS

In the reported experiments, adsorbed gelatin layers have been characterized by measuring the surface equilibrium tension and surface rheological parameters of shear, found by surface creep experiments. After the determination of these parameters the solution below the adsorption layer (gelatin plus phosphate buffer) was substituted by a gelatin-free phosphate-buffer-solution. The differences of the parameters calculated before and after the substitution of the bulk phase allowed us to prove some model assumptions of the protein adsorption and to characterize the physical contents of some of the surface rheological parameters determined. The parameters calculated and measured permit the distinction of three different concentration ranges of gelatin: (1) the range of reversible adsorption layer; (2) the ranges of saturated, irreversible adsorption layer; and (3) the range of multilayer formation.