Formation of cell-sized single-layered liposomes in a simple system of phospholipid, ethanol and water.

A mixture of an ethanolic solution of phospholipid and water was sonicated, kept at 50 degrees C for 30 min, and then observed by a phase-contrast microscope. A large number of cell-sized, single-layered liposomes thus obtained were different in shape and thickness from the liposomes prepared by conventional methods. Fixation with La(NO3)3 and KMnO4 stabilized the liposomes. As a result they remained unchanged in the organic solvents used for dehydration and embedding. Ultrathin sections of the liposomes could, therefore, be observed with an electron microscope. The nature of these liposomes was discussed in relation to the structure and function of the cell membrane.