Coexistence of nanoscopic domains in synthetic membranes

Abstract

The coexistence in the same membrane of nanoscopic domains with different crystal structures, as predicted by molecular dynamics modelling, is here experimentally demonstrated for the first time by direct imaging. These domains have been induced in liposomes made of PLPC (1-palmitoyl-2-linoleoyl-3-phosphatidylcholine) by adding different amounts of cardiolipin (tetra-acyl-diphosphatidyl-glycerol) during preparation. It has also been found that the process of controlled lipid peroxidation deletes the lateral phase separations. All these results, obtained with atomic force microscopy, provide experimental evidence for the hydrophobic mismatch theory of lateral phase separation phenomena. The images, taken in a liquid cell, show a spatial resolution to better than 0.4 nm.