Issue
EPL
Volume 80, Number 4, November 2007
Article Number 48002
Number of page(s) 6
Section Interdisciplinary Physics and Related Areas of Science and Technology
DOI http://dx.doi.org/10.1209/0295-5075/80/48002
Published online 10 October 2007
EPL, 80 (2007) 48002
DOI: 10.1209/0295-5075/80/48002

Unbinding of lipid bilayers induced by osmotic pressure in relation to unilamellar vesicle formation

N. L. Yamada1, M. Hishida2, H. Seto2, K. Tsumoto3 and T. Yoshimura3

1  Institute of Materials Structure Science, High Energy Accelerator Research Organization - Oho, Tsukuba, Ibaraki, 305-0801, Japan
2  Department of Physics, Kyoto University - Kitashirakawa-oiwake-cho, Sakyo, Kyoto, 606-8502, Japan
3  Department of Chemistry for Materials, Mie University - Kurimamachiya-cho, Tsu, Mie, 514-8507, Japan

yamadan@post.kek.jp

received 12 March 2007; accepted in final form 13 September 2007; published November 2007
published online 10 October 2007

Abstract
Small-angle X-ray scattering and phase-contrast microscopy experiments were performed to investigate the effect of osmotic pressure on vesicle formation in a dioleoyl-phosphatidylcholine (DOPC)/water/NaI system. The multi-lamellar structure of lipid bilayers is unstabilized when a lipid film with a sufficient amount of NaI is hydrated by pure water. It has been confirmed that this phenomenon is due to the effect of osmotic pressure induced by a hetero- geneous distribution of NaI molecules. This could be the origin of the unbinding of lipid bilayers to conform large uni-lamellar vesicles.

PACS
87.14.Cc - Lipids.
87.16.Dg - Membranes, bilayers, and vesicles.
61.10.Eq - X-ray scattering (including small-angle scattering).

© Europhysics Letters Association 2007