Coexistence of nanoscopic domains in synthetic membranes

The coexistence in the same membrane of nanoscopic domains with different c rystal structures, as predicted by molecular dynamics modelling, is here ex perimentally demonstrated for the first lime by direct imaging. These domai ns have been induced in liposomes made of PLPC (1-palmitoyl-2-linoleoyl-3-p hosphatidylcholine) by adding different amounts of cardiolipin (tetra-acyl- diphosphatidyl-glycerol) during preparation. It has also been found that th e process of controlled lipid peroxidation deletes the lateral phase separa tions. All these results, obtained with atomic force microscopy, provide ex perimental evidence for the hydrophobic mismatch theory of lateral phase se paration phenomena. The images, taken in a liquid cell, show a spatial reso lution to better than 0.4 nm.