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MEASUREMENTS OF CONFORMATION CHANGES DURING ADHESION OF LIPID PROTEIN (POLYLYSINE AND S-LAYER) SURFACES
Citation:
Leckband, D., Y. Chen, J. Israelachvili, H. Wickman, M. Fletcher, AND R. Zimmerman. MEASUREMENTS OF CONFORMATION CHANGES DURING ADHESION OF LIPID PROTEIN (POLYLYSINE AND S-LAYER) SURFACES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/410.
Description:
The adhesion forces between various surfaces were measured using the "surface forces apparatus" technique which allows for the thickness of surface layers and the adhesion force between them to be directly measured in controlled vapor or liquid environments. hree types of biological surfaces were prepared by depositing various lipid-protein monolayers (with thicknesses ranging from 1 to 4 nm) on the inert, molecularly smooth mica surface: (i) hydrophobiz lipid monolayer; (ii) amphiphilic polyelectrolyte surfaces of adsorbed polylysine; and (iii) deposited bacterial S-layer proteins. he adhesion, swelling, and wetting properties of these surfaces was measured as a function of relative humidity and time. nitial adhesion is due mainly to the van der Waals forces arising from nonpolar (hydrophobic) contacts. ollowing adhesive contact, significant molecular rearrangements can occur which alter their hydrophobic-hydrophilic balance and increase their adhesion with time. he results are likely to be applicable to the adhesion of any other biosurfaces, and show that the hydrophobicity of a lipid or protein surface is not an intrinsic property of that surface but depends on its environment and on the relative humidity of the atmosphere. t also depends on whether the surface is in adhesive contact with another surface and - when considering dynamic (nonequilibrium) conditions - on the time and previous history of its interaction with that surface.