ADSORPTION-KINETICS OF PROTEINS ONTO POLYMER SURFACES AS STUDIED BY THE MULTIPLE INTERNAL-REFLECTION FLUORESCENCE METHOD

Adsorption processes of proteins labeled with fluorescein (human serum albumin (FITC-HSA) and immunoglobulin G (FITC-IgG)) onto various polymer surfaces were followed by the multiple internal reflection fluorescence (MIRF) method. The FITC-proteins were adsorbed strongly onto hydrophobic polymer surfaces (poly(methyl methacrylate) (PMMA) and polystyrene (PSt)), and the proteins adsorbed were scarcely removed by rinsing with a buffer solution. The initial rate of the adsorption of FITC-proteins onto various polymer surfaces showed that the proteins were adsorbed more quickly onto hydrophobic surfaces than hydrophilic surfaces (plasma-treated PMMA, for example). Even the initial rate of adsorption onto a PSt surface (the most hydrophobic materials examined here) was, however, still smaller than that calculated from the diffusion-limited rate of arrival of the protein molecule to the surface, probably due to the hydrodynamic effect and the hydration layer around the protein molecule.