Adsorption of serum proteins from blood onto an artificial surface constitutes the initial event in the sequence of steps leading to thrombus formation. Thus, understanding the protein adsorption phenomenon is essential to elucidating the mechanisms responsible for blood/surface compatability. Total internal reflection fluorescence (TIRF) has been shown to be a versatile tool for studying protein adsorption onto solid surfaces. The research program described herein is directed toward the use of TIRF in improving our understanding of the various aspects of protein adsorption behavior. These include chemical equilibrium between surface-adsorbed proteins and protein molecules in the bulk solution, intrinsic adsorption kinetics, reversibility of adsorption, desorption kinetics, exchange of adsorbed proteins by molecules in solution, and competitive adsorption of protein molecules from multiple protein solutions. The protein adsorption process can be strongly influenced by convection/diffusion limitations, thus quantifying the effect of these mass transfer limitations will be a central concern of the proposed research. Specifically, the adsorption behavior of the three main serum proteins, gamma-globulin, fibrinogen and albumin onto silicone rubber surfaces in well-characterized flow systems will be investigated.