title: Controlled deformation of vesicles by flexible structured media.
abstract: Liquid crystalline (LC) materials, such as actin or tubulin networks, are known to be capable of deforming the shape of cells. Here, elements of that behavior are reproduced in a synthetic system, namely, a giant vesicle suspended in a LC, which we view as a first step toward the preparation of active, anisotropic hybrid systems that mimic some of the functionality encountered in biological systems. To that end, we rely on a coupled particle-continuum representation of deformable networks in a nematic LC represented at the level of a Landau-de Gennes free energy functional. Our results indicate that, depending on its elastic properties, the LC is indeed able to deform the vesicle until it reaches an equilibrium, anisotropic shape. The magnitude of the deformation is determined by a balance of elastic and surface forces. For perpendicular anchoring at the vesicle, a Saturn ring defect forms along the equatorial plane, and the vesicle adopts a pancake-like, oblate shape. For degenerate planar anchoring at the vesicle, two boojum defects are formed at the poles of the vesicle, which adopts an elongated, spheroidal shape. During the deformation, the volume of the topological defects in the LC shrinks considerably as the curvature of the vesicle increases. These predictions are confirmed by our experimental observations of spindle-like shapes in experiments with giant unilamellar vesicles with planar anchoring. We find that the tension of the vesicle suppresses vesicle deformation, whereas anchoring strength and large elastic constants promote shape anisotropy.
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Rui
authors.identifier: 0000-0002-2346-345X
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Ye
authors.identifier: 0000-0002-4618-9318
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
authors.forename: José A
authors.identifier: 0000-0001-7257-8889
authors.initials: JA
authors.lastname: Martínez-González
authors.affiliation: Departamento de Materiales, Universidad Nacional de Colombia, Medellin 050034, Colombia.
authors.forename: Juan P
authors.identifier: 0000-0003-0404-9947
authors.initials: JP
authors.lastname: Hernández-Ortiz
authors.affiliation: Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Abbott
authors.affiliation: Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: de Pablo
mesh_terms: D000199:Actins / Q000737:chemistry; D016880:Anisotropy; D048430:Cell Shape; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D050866:Liquid Crystals / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics; D022161:Transport Vesicles / Q000737:chemistry* / Q000378:metabolism; D014404:Tubulin / Q000737:chemistry; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D000199:Actins; D008051:Lipid Bilayers; D014404:Tubulin; D053835:Unilamellar Liposomes
keywords: Landau-de Gennes model; Nematic liquid crystal; lyotropic chromonic liquid crystal; unilamellar giant vesicle; vesicle deformation