title: Control of active liquid crystals with a magnetic field.
abstract: Living cells sense the mechanical features of their environment and adapt to it by actively remodeling their peripheral network of filamentary proteins, known as cortical cytoskeleton. By mimicking this principle, we demonstrate an effective control strategy for a microtubule-based active nematic in contact with a hydrophobic thermotropic liquid crystal. By using well-established protocols for the orientation of liquid crystals with a uniform magnetic field, and through the mediation of anisotropic shear stresses, the active nematic reversibly self-assembles with aligned flows and textures that feature orientational order at the millimeter scale. The turbulent flow, characteristic of active nematics, is in this way regularized into a laminar flow with periodic velocity oscillations. Once patterned, the microtubule assembly reveals its intrinsic length and time scales, which we correlate with the activity of motor proteins, as predicted by existing theories of active nematics. The demonstrated commanding strategy should be compatible with other viable active biomaterials at interfaces, and we envision its use to probe the mechanics of the intracellular matrix.
authors.affiliation: Departament de Química Física, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain; Institute of Nanoscience and Nanotechnology, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain.
authors.forename: Pau
authors.initials: P
authors.lastname: Guillamat
authors.affiliation: Departament de Química Física, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain; Institute of Nanoscience and Nanotechnology, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain.
authors.forename: Jordi
authors.identifier: 0000-0001-7963-3799
authors.initials: J
authors.lastname: Ignés-Mullol
authors.affiliation: Departament de Química Física, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain; Institute of Nanoscience and Nanotechnology, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain f.sagues@ub.edu.
authors.forename: Francesc
authors.initials: F
authors.lastname: Sagués
mesh_terms: D005782:Gels; D050866:Liquid Crystals / Q000737:chemistry*; D060526:Magnetic Fields; D008870:Microtubules / Q000737:chemistry
chemical_list: D005782:Gels
keywords: active matter; cytoskeleton; kinesin; liquid crystals