Title: Control of Active Liquid Crystals by Means of Addressable Soft Interfaces

Abstract: 

Active liquid crystals are aqueous in vitro suspensions of cytoskeletal proteins that self-assemble into elongated fibers and develop sustained flows at the continuous expense of ATP. When they condense on soft interfaces, the aligned fibers organize into non equilibrium analogs of passive liquid crystals. However, proteins do not respond to external electromagnetic fields, unlike liquid crystals, which are readily reconfigured inside devices. We demonstrate a reversible and bio-compatible experimental protocol to align an active liquid crystal with a uniform magnetic field, allowing the transition between turbulent and laminar flow regimes. The active liquid crystal senses the interfacial viscous anisotropy of a lamellar hydrophobic liquid crystal, not unlike the adaptation of cells to the mechanical features of their environment. 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.