Lateral electrical conduction along a phosphatidylcholine monolayer.

Lateral electrical conduction due to lipid-monolayers spread on the surface of pure water was observed under both d.c. and a.c. electrical fields. An apparent specific electrical conductivity is evaluated as high as approximately equal to 4.10(-2) mho/cm for the monolayer-water system of L-DPPC at 25 degrees C. Arrhenius plots of the apparent conductance show a deflection at a temperature corresponding to a crystalline-to-fluid phase transition of the surface monolayer. From the magnitude and temperature dependence of conductance and a comparison of results with those obtained by use of deuterated water, it is concluded that enhanced protonic conduction mediated by a network consisted of polar head groups of phosphatidylcholines and water molecules may be brought about near the lipid/water interface.