Tube extrusion from permeabilized giant vesicles

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

Corresponding author: brochard@curie.fr

Received: 30 March 2006
Accepted: 20 June 2006

Abstract

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 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 strongly depends on surfactant concentration. For Streptolysin O, we have measured vs. U and found two regimes: a “high-porosity” regime for and a “low-porosity” regime for , where is related to the number of pores on the vesicle surface.