Unbinding transition of a biological model membrane

We have discovered a temperature-driven unbinding transition of fluid membranes in samples of digalactosyldiacylglycerol (DGDG) swollen in 0.1M NaCl aqueous solution. Single bilayers were observed by phase contrast light microscopy. The transition is reversible and without apparent hysteresis. Its temperature is only a few °C lower for the single membranes of two vesicles than for multilayer systems, but it varies strongly among samples. The bending rigidity of DGDG bilayers was also measured and found to be (0.12–0.21)×${10}^{\mathrm{-}12}$ erg.