Line tension in lipid monolayers with liquid-liquid phase coexistence

A. A. BISCHOF , N. WILKE

San Diego

Congreso; 56th Annual Meeting of the Biophysical Society.; 2012

Biophysical Society.

The line tension () in biphasic membranes has been determined in monolayers and bilayers using several techniques. In this work, we present a manner of determining  in monolayers with liquid/liquid phase coexistence that overcomes some of the drawbacks of currents methods. Using this new technique, we determined the line tension of liquid/liquid phases in binary mixtures of different lipids and a molecule similar to cholesterol but less oxidable. We analyzed the effect of the hydrocarbon chain length and of the polar head-group of the non-sterol lipid at 4 mN/m. The results indicate that an increase of 12 to 16 carbons in the hydrocarbon chain did not influence the value of . In contrast, the nature of the polar head-group had an important influence on ; PE induced high  values while PG led to low values, with PS and PC producing intermediate ones. The line tension showed a strong correlation with the critical packing parameter of the phospholipid. The spontaneous tendency to curvature of the phases constituted by a particular lipid appears to be an important parameter for determining the line tension in mixed films.