Engineering Research Equipment Grant: A Surface Force Instrument for Adhesion Membrane Transport and Polymer Studies

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The equipment provided by this project allows three investigators who recently have been awarded an NSF "minicenter" grant to study cell separations mediated by receptor-ligand interactions. The surface force instrument (SFI) provides direct information on the strength of such bonds, the distances over which they are effective, and in the case of fluid membrane surfaces (modeled by lipid bilayers deposited on the mica surfaces) how rapidly the bond-forming molecules can diffuse into close proximity to one another. The transport of molecules through membranes is also of great interest to two other researchers. The SFI provides direct information on the partitioning of molecules between pore (modeled by the thin slit "pore" of the two mica surfaces) and bulk liquid. Predictions suggesting an oscillatory variation in the partition coefficient as pore radius changes can be tested. Many fundamental materials properties are directly dependent on intermolecular forces. These properties, in turn, are used directly in chemical engineering calculations to predict and correlate polymer solubility, colloid stability, adhesion, membrane permeation, adsorption, and other phenomena. In the past, it has been necessary to use derived quantities as a measure of these interactions. The SFI permits direct measurement of these forces and how they vary with position. It therefore has the potential for making important contributions to many areas of chemical engineering: in producing accurate "first-principles" data, in testing theoretical predictions based on molecular interactions, and i helping to produce improved correlating functions.