Weakly adhering vesicles in shear flow: Tanktreading and anomalous lift force

Abstract

We report the deformation and unbinding of weakly adhering giant vesicles under hydrodynamic shear forces. Linear shear fields are generated in a flat cell and vesicle adhesion onto a supported membrane is generated by electrostatic forces between oppositely charged lipids. The hydrodynamic flow in the aqueous medium near the outer side of the vesicle, within the vesicle and the tanktreading motion in the membrane are observed by tracing small markers attached to the vesicles or suspended in the medium by confocal laser scanning microscopy. The lift force generated by the rotational flow in the vesicle was estimated to be at least two orders of magnitude larger than predicted by the simple theory.