Interfacial tension of phosphatidylcholine–cholesterol system in monolayers at the air/water interface Original Research Article

Interfacial tension of an egg lecithin–cholesterol system was measured across the whole concentration range. Surface pressure–area isotherm measurements were carried out in a Langmuir trough at the air/water interface at room temperature (22 °C). The interfacial tension of the air/water interface was divided into contributions of components. The interfacial tension of a 1:1 complex between phosphatidylcholine and cholesterol was calculated. Its value equals 18 mN/m. The difference between the stability constant of 1:1 complex in the bilayer and the monolayer at the air/water interface is discussed.