A continuation of FF-IR/ATR studies for the surface characterization of biomaterials through protein adsorption studies is proposed. The rapid adsorption of blood proteins to the surfaces of implants is recognized as the important initial event in blood-materials interactions. The response of the human host towards the implant is mediated by the properties of the adsorbed protein layer. Fourier Transform InfraRed (FT-IR) Attenuated Total internal Reflection (ATR) techniques provide a powerful-means of studying the initial events in protein-biomaterial interactions. The FT-IR/ATR technique provides molecular level information about blood-materials interaction: protein adsorption kinetics, conformation and orientation. Development and application of novel techniques in this proposal will allow the development of fundamental understanding of structural changes in significant blood proteins upon adsorption to biomaterial surfaces. Techniques for synthesis and attachment of infrared labels to albumin, IgG and fibrinogen will be refined. These DR labels, which have absorbance bands in the spectral region from 2000 to 1800 1/cm, will allow more precise determination of the concentration and conformation of the labeled proteins in complex protein mixtures. The adsorption kinetics of albumin, IgG and fibrinogen will be determined from simple binary and ternary systems. Using adsorbed protein concentrations, spectral reconstruction techniques will be used to extract the spectrum of individual proteins adsorbed to surfaces. Spectral analysis will reveal changes in protein conformation. Thus information on the conformation of a particular adsorbing protein will be determined in the presence of other, unlabelled proteins. A quantitative measure for adsorbed protein heterogeneity and a mean strength of protein binding to surfaces will also be obtained. A mathematical model for protein adsorption with parameters directly related to specific information from the Amide I and II bands will be developed. This model will include total protein (Amide II) and estimates of denatured protein (changes in underlying bands of Amide I and II). Protein adsorption will be studied on surfaces which are water-stable, highly uniform and have a well controlled surface composition. Development of these new methods, the model and their extension to studies of protein adsorption from plasma and whole blood will provide the biomaterial scientist with a sensitive technique with which to understand the critical initial events in blood-materials interactions.
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