Nature 272, 268 - 270 (16 March 1978); doi:10.1038/272268a0

Lipid-dependent and phloretin-induced modifications of dipicrylamine adsorption by bilayer membranes

C.-C. WANG & L. J. BRUNER

Department of Physics, University of California, Riverside, Riverside, California 92521

THE hydrophobic anions of dipicrylamine (DpA^-) and of sodium tetraphenylborate (TphB^-) have been shown to adsorb at deep potential minima near the surfaces of lipid bilayer membranes¹. Use of a high field voltage-jump technique has led to direct measurement of the membrane surface charge density attributable to adsorption of these anions^2,3, and analyses of such measurements have shown that the magnitude of the membrane surface potential resulting from adsorption of both DpA^- and TphB^- is too large to be accounted for by conventional Gouy−Chapman theory^4,5. Crucial to an understanding of this discrepancy is the question of the location of the plane of adsorbed charge relative to the membrane−solution interface. Experimental results reported here are consistent with the conclusion that these planes are coincident.

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