KINETICS OF SINGLE AND COMPETITIVE PROTEIN ADSORPTION STUDIED BY REFLECTOMETRY AND STREAMING POTENTIAL MEASUREMENTS

Changes in the reflectivity or streaming potential of polystyrene-covered silicon wafers or glass plates, respectively, upon the addition of proteins can be interpreted in terms of adsorbed amounts and/or adsorption rates. The rates of supply are given by hydrodynamic equations. We investigated the adsorption of BSA and four monoclonal immunoglobulins with different isoelectric points as a function of concentration and pH. Apart from the rate of supply, the amounts adsorbed also depend on the electrostatic interaction between proteins and surface. These observations complement adsorption measurements on polystyrene latices. The two techniques may also be used to obtain additional information regarding simultaneous and sequential adsorption of more than one protein.