SANS study of mixed POPC/C12En aggregates

The structure of the mixed POPC/C12En (n = 6,8) supramolecular aggregates i s characterized by SANS. The dilute aqueous phospholipid-surfactant systems show a bilayer-micelle phase transition upon increasing effective detergen t mole fraction in the aggregates. In the mixed lamellae, thinning of the b ilayer thickness is found with increasing detergent molar fraction. On furt her increase of detergent molar fraction, subsequent transitions from the l amellar phase to rod-like micelles, ellipsoidal micelles and, finally, into spherical micelles are revealed. Geometric parameters of the different agg regates are estimated by Guinier analysis of the SANS curves. (C) 2000 Else vier Science B.V. All rights reserved.