Maxwell Displacement Current across Phospholipid Monolayers at the Air/Water Interface

Abstract

The organization of phospholipid monolayers on a water surface was investigated by means of the Maxwell displacement current (MDC) measurement technique. The phase transition from the gaseous phase to the gaseous-fluid phase which accompanies the polar ordering of lipid molecules was detected by the technique in the range of immeasurably low surface pressure, and the molecular area which gives the onset of the transition was determined for various lipid monolayers. The vertical component of the dipole moment of lipid membranes was determined from the charge flowing through the circuit, and it was also determined by a curve-fitting method from the MDC generated in the fluid phase.