Europhys. Lett.
Volume 75, Number 4, August 2006
Page(s) 666 - 672
Section Interdisciplinary physics and related areas of science and technology
Published online 07 July 2006
Europhys. Lett., 75 (4), pp. 666-672 (2006)
DOI: 10.1209/epl/i2006-10142-5

Tube extrusion from permeabilized giant vesicles

N. Borghi, S. Kremer, V. Askovic and F. Brochard-Wyart

Laboratoire PCC Institut Curie/CNRS UMR 168 - 11 rue P. & M. Curie 75231 Paris Cedex 05, France

received 30 March 2006; accepted in final form 20 June 2006
published online 7 July 2006

This letter reports the permeabilization effects of chemical additives on mechanical properties of Giant Unilamellar Vesicles (GUVs). We use a surfactant, Tween 20, inducing transient pores and a protein, Streptolysin O, inducing permanent pores in the membrane. Lipid tubes are extracted from GUVs anchored onto the tip of a micro-needle and submitted to hydrodynamic flows. On bare vesicles, tube extrusion is governed by the entropic elasticity of the membrane. The vesicle tension increases until it balances the flow velocity U and the tube reaches a stationary length. In permeabilized vesicles, the membrane tension is maintained at a constant value $\sigma_{\ab{p}}$ by the permeation of inner solution through nanometric pores. This allows extrusion of "infinite" tubes at constant velocity that never reach a stationary length. Tween-20 preliminary results suggest that $\sigma_{\ab{p}}$ strongly depends on surfactant concentration. For Streptolysin O, we have measured $\sigma_{\ab{p}}$ vs. U and found two regimes: a "high-porosity" regime for $U>U_{\ab{p0}}$ and a "low-porosity" regime for $U<U_{\ab{p0}}$, where $U_{\ab{p0}}$ is related to the number of pores on the vesicle surface.

87.16.Dg - Membranes, bilayers and vesicles.
87.15.Kg - Molecular interactions; membrane-protein interactions.
87.83.+a - Biomedical applications of nanotechnology.

© EDP Sciences 2006