A mechanochemical study of the process of adhesion of plasma proteins to the surface of dialysis membranes was carried out with a scanning force microscope (SFM) in the force spectroscopy mode. Three representative blood plasma proteins (fibronectin, fibrinogen, and albumin) covalently were grafted to a SFM probe, and the adhesion forces of these proteins to cellulosic and synthetic dialysis membranes were measured. The experiment was tailored to apply a controlled load on the protein molecules adsorbed onto the surface in order to simulate the squeezing forces exerted on them during blood filtration. The de-adhesion forces, measured using this new approach for studying the interaction between a protein and dialysis membranes, suggest that the membrane's topography, at a nanometer scale, plays a critical role in the adhesion process. This result was strongly supported by parallel experiments performed on a flattened glass surface with the same dominant hydrophilic character as dialysis membranes. In contrast, a hydrophobic polystyrene surface led to de-adhesion forces at least one order of magnitude greater, overwhelming any possible shape recognition process between the protein molecules and the surface.
Copyright 2002 Wiley Periodicals, Inc.