SIZE-DEPENDENT RESPONSE OF LIPOSOMES TO PHOSPHOLIPID TRANSMEMBRANE REDISTRIBUTION - FROM SHAPE CHANGE TO INDUCED TENSION

We show theoretically that the behavior of a unilamellar liposome in response to a phospholipid transmembrane redistribution depends on the characteristic size of the liposome. For liposomes with a diameter of several micrometers, a redistribution of the order of 0.1% is sufficient to trigger a shape change from prolate (or discoid) to pear-shaped vesicle. For liposomes with a diameter of the order of 0.1 mum or less, lipid transmembrane redistribution cannot trigger important shape change but will induce a tension in the bilayer, susceptible to inhibit the thermal undulations of the liposome. We speculate about possible implications of this scaling effect on the biological function of cell membranes.