Interrelationships between the phase diagrams of the two-component phospholipid bilayers
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Updated: Sep 3, 2026

Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers
Published on: July 22, 2015
Abstract:
Basic relationships between the phase diagrams, previously considered independent of each other, are described. Phase diagrams of two-component phosphatidylcholine/phosphatidylcholine (PC/PC), phosphatidylethanolamine/phosphatidylethanolamine (PE/PE), and PC/PE lipid membranes are systematically investigated by means of the Landau theory. While gradually changing the chain length of one of the components, a characteristic peritectic-miscible-azeotropic-semiazeotropic-eutectic (P-M-A-S-E) series of the phase diagram was found in the PC/PE system and a peritectic-miscible-one-component-miscible-peritectic (P-M-O-M-P) series was found in the PC/PC and PE/PE systems. These serial catastrophic changes in the phase diagrams could be explained by the fusion and birth of the mixed phase regions in the phase diagram. Finally when we constructed the superdiagrams, we obtained all of the possible series of the phase diagrams in a wide class of the two-component mixtures. Moreover, one can predict the type of the phase diagram when the components r and p contain equal-length saturated hydrocarbon chains. Depending on the relationships between the chain lengths (L, Lp) and that on the phase transition temperatures of the pure components (Tr, Tp), the system is: miscible (M), if 0 < Tr(L) - Tp(L) < 5 degrees C and L -Lp > 0, azeotropic (A), if 0 < T,(L) - Tp(L) < 5 degrees C and L -Lp < 0, peritectic (P), if T,(L) - Tp(L) > 40 degrees C and L -Lp - 0, eutectic (E), if Tr(L) - Tp(L) >40 degrees C and L - Lp <0,while it is M or P if 5 degrees C< Tr(L) - Tp(L) <40 degrees C and L - Lp>-0,and E,S,or Aif 5 degrees C < Tr(L) - Tp(L) < 40 degrees C and L,-Lp < 0.
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