Nanotubes from asymmetrically decorated vesicles

Abstract

Hydrodynamic nanotube extrusion is used to characterize chitosan-decorated vesicles, which are more robust to pH and salt shocks and exhibit specific behavior under osmotic pressure if compared to their bare homologues. The vesicle attached to a micro-rod is submitted to a flow. Above a threshold velocity, we observe the extrusion of a lipidic nanotube. We study how it grows and relaxes when the flow is stopped. We find that extrusion forces for decorated vesicles are weaker than for bare vesicles. We interpret these results using a model that introduces the spontaneous curvature due to asymmetric adsorption of chitosan on the external leaflet of the bilayer, which allows us to calculate the stationary length of the tube versus the flow velocity and to estimate the spontaneous curvature c₀.