Lipid monolayers on Hg as a valid experimental model for lipid membranes under electrical fields

Monolayers spread on Hg drops are shown as a suitable experimental set up to study the influence of external electric fields on the structure of lipid membranes. The electrical response exhibits a sharp transition at 24 degrees C, the transition temperature of DMPC. In addition, voltammetric response of monolayers of mixtures of DMPC/DMPE adsorbed on mercury, shows a similar trend to that found for dipole potential of monolayers of the same composition spread on an air-solution interface. It is concluded that a lipid monolayer adsorbed in a mercury-solution interface, has comparable properties as those found in other experimental models of lipid membranes in similar conditions. In addition, they constitute an ideal set up to study the effect of electrical fields on the dynamic conformation of lipids as a function of packing change produced by the condensation in the gel state or by the interaction of polar head groups. (C) 2005 Elsevier Ireland Ltd. All rights reserved.