The equilibria between monovalent ions and phosphatidylcholine monolayer at the air/water interface

Abstract

The effect of monovalent ion (Li+, Na+, Cs +) interaction with monolayers of phosphatidylcholine (lecithin, PC) was investigated at the air/water interface. We present surface tension measurements of lipid monolayers obtained using a Langmuir method as a function of monovalent ion concentration. Measurements were carried out at 22 C using a Teflon trough and a Nima 9000 tensiometer. Interactions between lecithin and monovalent ions result in significant deviations from the additivity rule. An equilibrium theory to describe the behavior of monolayer components at the air/water interface was developed in order to obtain the stability constants and area occupied by one molecule of PC-monovalent ion complexes (PC -Me+). © 2013 The Author(s).