Abstract approved: J The sequential and

petitive adsorption of bovine serum albumin (BSA) and 0-lactoglobulin at silanized silica surfaces were investigated using protein radiolabeling and in-situ ellipsometry. Simultaneous adsorption of It-labeled BSA and 0-lactoglobulin revealed an initial dominance of the surface by 0-lactoglobulin, with subsequent replacement by BSA. In sequential adsorption experiments, where the surface was contacted with 14C- labeled BSA, followed by contact with protein-free buffer and addition of P-lactoglobulin, most of the adsorbed BSA was not removed. Listeria monocytogenes adhesion to protein films prepared with BSA and 0-lactoglobulin adsorbed in sequence and simultaneously was explainable with reference to the passivating character of adsorbed BSA, and its resistance to elution as measured here. The effect of adding a-lactalbumin, 0-casein and 0-lactoglobulin to adsorbed BSA as well as the effect of adding a-lactalbumin, 0-casein and BSA to adsorbed P-lactoglobulin was investigated using in-situ ellipsometry. 0-casein was the most effective eluting agent, while Redacted for Privacy a-lactalbumin was the least effective. The abilities of a-lactalbumin and 0-casein to exchange with adsorbed BSA and 0-lactoglobulin were evaluated with reference to a simple kinetic model for protein adsorption and exchange. The model is based on a mechanism allowing for reversible adsorption followed by either a surface-induced conformational change yielding an irreversibly adsorbed form or exchange with the dissimilar protein. Differences in exchange behavior were generally found to be consistent with the rate constant for surface-induced conversion of the adsorbed protein as opposed to describing exchange of adsorbed protein with a dissimilar protein. This suggests that under these experimental conditions exchange was mediated by a protein-surface interaction, i.e., a displacement mechanism, where protein-protein associations were of minor significance