Segregation of saturated chain lipids in pulmonary surfactant films and bilayers.

K. NAG; J.S. PAO; R.R. HARBOTTLE; F. POSSMAYER; N.O. PETERSEN; LUIS A. BAGATOLLI

BIOPHYSICAL JOURNAL

CELL PRESS

Lugar: United States; Año: 2002 vol. 82 p. 2041 - 2041

0006-3495

he physical properties of organized system (bilayers and monolayers at the air water interface) composed of bovine lipid extract surfactant (BLES) were studied using correlated experimental techniques. 6-Dodecanoyl-2-dimethylamino-naphthalene (LAURDAN)-labeled giant unilamelar vesicles (mean diameter approximately 30 microm) composed of BLES were observed at different temperatures using two-photon fluorescence microscopy. As the temperature was decreased, dark domains (gel-like) appeared at physiological temperature (37 degrees C) on the surface of BLES giant unilamelar vesicles. The LAURDAN two-photon fluorescent images show that the gel-like domains span the lipid bilayer. Quantitative analysis of the LAURDAN generalized polarization function suggests the presence of a gel/fluid phase coexistence between 37 degrees C to 20 degrees C with low compositional and energetic differences between the coexisting phases. Interestingly, the microscopic scenario of the phase coexistence observe