Electrochemical methods applied to the interface between two immiscible electrolyte solutions (ITIES) have been used to examine kinetic and analytical aspects of the transport of various drugs, to determine partition coefficients from transfer potentials and to clarify the electrochemical behavior of structurally specific and nonspecific drugs. An important application of these systems is related with the study of liquid – liquid interfaces modified by the adsorption of a lipid monolayer, since it provides information about the interaction of inorganic ions, biological compounds, pharmaceutical drugs and macromolecules with membranes as well as about their transfer across them.
In this presentation the application of electrochemical measurements at modified liquid – liquid interfaces as an approach to study the structure and permeability of different lipid films is shown. Several systems are studied employing cyclic voltammetry and impedance spectroscopy as main techniques. In this way, the results obtained for zwitterionic (distearoyl phosphatidyl ethanolamine, DSPE, and distearoyl phosphatidyl choline, DSPC) and anionic (distearoyl phosphatidyl glycerol, DSPG) phospholipids in the presence of Ca2+, Li+ and K+ as aqueous electrolytes are discussed. Also, the effect of different molecules such as psychoctropic drugs (benzodiazepines and fenothizines), cholesterol and polyelectrolytes on the packing properties of monolayers is presented. The use of a test cation such as TEA+, allowed us to evaluate the permeability and the compactness of the film. On the other hand, the modification of an immobilized water/ gelled 1,2-dichloroethane interface with a Langmuir-Blodgett monolayer deposited at different surface pressures is shown.
