Oscillatory phase separation in giant lipid vesicles induced by transmembrane osmotic differentials

• Published in: eLife Vol. 3; p. e03695
• Main Authors: Oglęcka, Kamila, Rangamani, Padmini, Liedberg, Bo, Kraut, Rachel S, Parikh, Atul N
• Format: Journal Article
• Language: English
• Published: England eLife Sciences Publications Ltd 15.10.2014; eLife Sciences Publications, Ltd
• Subjects: Animals; BASIC BIOLOGICAL SCIENCES; Biophysics and Structural Biology; Cell Biology; Chickens; compartmentalization; giant phospholipid vesicle; Hypertonic Solutions - pharmacology; Hypotonic Solutions - pharmacology; Life Sciences & Biomedicine - Other Topics; Lipid Bilayers - chemistry; lipid raft; Lipids; Materials science; Microscopy; Oscillations; Osmosis; Osmosis - drug effects; Osmotic pressure; Permeability - drug effects; phase separation; Phase Transition - drug effects; Phase transitions; Porosity; primitive osmoregulation; Shells; Solutes; Sucrose; Temperature; Unilamellar Liposomes - chemistry; Vesicles; United States > US; California; lipid rafts; phase separation; cell biology; giant phospholipid vesicles; compartmentalization; structural biology; primitive osmoregulation; biophysics
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.03695

Giant lipid vesicles are closed compartments consisting of semi-permeable shells, which isolate femto- to pico-liter quantities of aqueous core from the bulk. Although water permeates readily across vesicular walls, passive permeation of solutes is hindered. In this study, we show that, when subject to a hypotonic bath, giant vesicles consisting of phase separating lipid mixtures undergo osmotic relaxation exhibiting damped oscillations in phase behavior, which is synchronized with swell-burst lytic cycles: in the swelled state, osmotic pressure and elevated membrane tension due to the influx of water promote domain formation. During bursting, solute leakage through transient pores relaxes the pressure and tension, replacing the domain texture by a uniform one. This isothermal phase transition--resulting from a well-coordinated sequence of mechanochemical events--suggests a complex emergent behavior allowing synthetic vesicles produced from simple components, namely, water, osmolytes, and lipids to sense and regulate their micro-environment.