Adsorption of serum proteins from blood onto an artificial surface constitutes the initial event in the sequence of steps leading to thrombus formation. Understanding of the protein adsorption phenomenon is, therefore, essential to elucidating the mechanisms responsible for blood-surface compatibility. The chemical heterogeneity of native serum proteins, however, prevents precise elucidation of the mechanisms responsible for protein/surface interactions. Thus, the research program described herein focuses on studying the interactions of chemically simple polyaminoacids (PAA) and their copolymers with a variety of polymeric surfaces. Total internal reflection fluorescence (TIRF) has been shown to be a versatile tool for studying the quantitative aspects of protein adsorption. This will be used to investigate the adsorption and desorption of kinetics, as well as to determine the maximum surface coverage for each PAA/surface pair. Fourier transform infrared spectroscopy/attenuated total reflection (FTIR/ATR) is capable of detecting conformation changes that protein molecules undergo during and after adsorption, and will be used to examine these conformational aspects of PAA adsorption. The protein and PAA adsorption processes can be strongly influenced by the presence of a shear field. The extent to which mass transfer limitations affect PAA adsorption rates depends on the strength of the shear field. In addition, PAA molecules may be oriented or denatured by shear. Thus, the effect of shear fields on PAA adsorption will be a central concern of the proposed research. Specifically, the adsorption characteristics of poly-lysine, poly-leucine, poly-glutamic acid and poly-tyrosine and the copolymers on polydimethylsiloxane, polydiphenylsiloxane, polycyanopropylmethylsiloxane, polymethylmethacrylate, polystyrene-sulfonate, polyethyleneoxide, polyvinylpyrrolidone, and polyhydroxyethylmethacrylate in well-characterized flow systems will be investigated. The results of these studies are expected to provide fundamental insights into the bonding reactions characteristic of proteins interacting with polymer surfaces in known hydrodynamic environments.
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