This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.104.056036v1 89/2/1055    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Abkarian, M. Articles by Viallat, A. Search for Related Content PubMed PubMed Citation Articles by Abkarian, M. Articles by Viallat, A.

Dynamics of Vesicles in a Wall-Bounded Shear Flow

M. Abkarian ^* and A. Viallat 

^* Department of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138; and Laboratoire de Spectrométrie Physique, Université J. Fourier, BP 87 38402 St Martin d'Hères cedex, France

Correspondence: Address reprint requests to Dr. Manouk Abkarian, E-mail: mabkaria{at}deas.harvard.edu.

We report a detailed study of the behavior (shapes, experienced forces, velocities) of giant lipid vesicles subjected to a shear flow close to a wall. Vesicle buoyancy, size, and reduced volume were separately varied. We show that vesicles are deformed by the flow and exhibit a tank-treading motion with steady orientation. Their shapes are characterized by two nondimensional parameters: the reduced volume and the ratio of the shear stress with the hydrostatic pressure. We confirm the existence of a force, able to lift away nonspherical buoyant vesicles from the substrate. We give the functional variation and the value of this lift force (up to 150 pN in our experimental conditions) as a function of the relevant physical parameters: vesicle-substrate distance, wall shear rate, viscosity of the solution, vesicle size, and reduced volume. Circulating deformable cells disclosing a nonspherical shape also experience this force of viscous origin, which contributes to take them away from the endothelium and should be taken into account in studies on cell adhesion in flow chambers, where cells membrane and the adhesive substrate are in relative motion. Finally, the kinematics of vesicles along the flow direction can be described in a first approximation with a model of rigid spheres.