| This thesis investigated protein adsorption kinetics and interfacial reconfiguration dynamics of proteins on surfaces of varying hydrophobicity.; With the model systems of bovine serum albumin and bovine serum fibrinogen adsorbing onto a series of uncharged self-assembled monolayers, initial adsorption kinetics from controlled shearing flow were found to be transport-limited and independent of surface chemistry. The final coverage was, however, observed to depend on the variables of the adsorption history; the flow rate or the bulk solution concentration. For the cases of albumin and fibrinogen on a variety of uncharged surfaces, the initial, zero-time footprint always corresponded to an area between that of the end-on and side-on adsorbed conformations, and was independent of surface chemistry.; The observation that interfacial spreading kinetics could be inferred from continuous adsorption traces led to more concerted efforts to directly probe interfacial relaxation dynamics. In these studies, a small amount of a test protein was adsorbed to a surface, and after various incubation times in buffer solution, the original adsorbed layer was exposed to a solution of probe molecules. From the adsorbed mass of the probe molecules and the known amount of initially adsorbed test protein, it was possible to calculate the footprint of the test molecules at various times after their initial adsorption. In this way, footprint spreading curves for test molecules were generated.; From the molecular probe studies, full spreading traces of fibrinogen were reported for several different surfaces. In all cases, the spreading kinetics appeared to be single exponential, a form which was consistent with a single, irreversible spreading event. It was discovered that a threshold energy of 6–7 kT was needed to retain fibrinogen at a hydrophobic interface, a binding strength consistent with the incorporation of C18 chains in hydrophobic aggregates.; These unfolding dynamics of fibrinogen were compared and contrasted with the interfacial dynamics of adsorbed lysozyme and albumin. Quantitative analysis unequivocally proved that during adsorption, lysozyme reorients from an end-on to a side-on configuration by means of rolling over, rather than desorption and readsorption. For the case of albumin, it was determined that interfacial denaturing did occur, but in contrast with the behavior of fibrinogen, spreading kinetics were not exponential and a more complicated set of interfacial states were thought to occur. (Abstract shortened by UMI.)... |
