Ion transfer across a phospholipid monolayer adsorbed at the water vertical bar 1,2-dichloroethane interface under surface pressure control

The influence of a monolayer of a lipid, distearoyl phosphatidylcholine, fo rmed at a water I dichloroethane interface in a special Langmuir trough, wh ich allows simultaneous control of the state of the monolayer and the poten tial across the interface, on the transfer of ions across this interface ha s been studied using two probe ions: the cationic drug propranolol and anio nic picrate, From measurement of the isotherms of the lipid monolayer and o f the cyclic voltammograms of propranolol and picrate at controlled surface pressure it was found that picrate stabilises the monolayer and that its t ransfer across the interface requires more energy in the presence than in t he absence of lipid. Propranolol. however, has a destabilising influence on the monolayer and accelerates lipid desorption. The kinetics of transfer o f both ions was too fast to be followed by cyclic voltammetry. (C) 1999 Els evier Science S.A. All rights reserved.