Confinement Controls the Bend Instability of Three-Dimensional Active Liquid Crystals

Chandrakar, Pooja; Varghese, Minu; Aghvami, S. Ali; Baskaran, Aparna; Dogic, Zvonimir; Duclos, Guillaume

doi:10.1103/physrevlett.125.257801

Cited by 55 publications

(67 citation statements)

References 65 publications

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“…Specifically, extensile active stresses drive the bend instability as we observed for the kinesin-4 system in the presence of bundling interactions [Fig. 8] [37,61]. Analogously, contractile systems exhibit splay instabilities, but these have not been experimentally observed.…”

Section: Discussionmentioning

confidence: 79%

Active microphase separation in mixtures of microtubules and tip-accumulating molecular motors

Lemma¹,

Mitchell²,

Subramanian³

et al. 2021

Preprint

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Mixtures of microtubules and molecular motors form active materials with diverse dynamical behaviors that vary based on their constituents' molecular properties. We map the non-equilibrium phase diagram of microtubules and tip-accumulating kinesin-4 molecular motors. We find that kinesin-4 can drive either global contractions or turbulent-like extensile dynamics, depending on the concentrations of both microtubules and a bundling agent. We also observe a range of spatially heterogeneous non-equilibrium phases, including finite-sized radial asters, 1D wormlike chains, extended 2D bilayers, and system-spanning 3D active foams. Finally, we describe intricate kinetic pathways that yield microphase separated structures and arise from the inherent frustration between the orientational order of filamentous microtubules and the positional order of tip-accumulating molecular motors. Our work shows that the form of active stresses and phases in cytoskeletal networks are not solely dictated by the properties of individual motors and filaments, but are also contingent on the constituent's concentrations and spatial arrangement of motors on the filaments.

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Section: Discussionmentioning

confidence: 79%

Active microphase separation in mixtures of microtubules and tip-accumulating molecular motors

Lemma¹,

Mitchell²,

Subramanian³

et al. 2021

Preprint

Self Cite

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“…This has the effect of pushing the fluid in the direction that the kinesin is moving, as well as (by Newton's third law) exerting a force on the microtubule in the opposite direction. As such, flows can be observed in the fluid with no external impetus, from vortex lattices [1] to 2-dimensional active nematics [2][3][4][5][6] to macroscopic effects like coherent flow [7] and shear-induced gelation [8].…”

Section: Introductionmentioning

confidence: 99%

Spontaneous circulation of active microtubules confined by optical traps

Martin

Brunner

2021

J Biol Phys

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We propose an experiment to demonstrate spontaneous ordering and symmetry breaking of kinesin-driven microtubules confined to an optical trap. Calculations involving the feasibility of such an experiment are first performed which analyze the power needed to confine microtubules and address heating concerns. We then present the results of first-principles simulations of active microtubules confined in such a trap and analyze the types of motion observed by the microtubules as well as the velocity of the surrounding fluid, both near the trap and in the far-field. We find three distinct phases characterized by breaking of distinct symmetries and also analyze the power spectrum of the angular momenta of polymers to further quantify the differences between these phases. Under the correct conditions, microtubules were found to spontaneously align with one another and circle the trap in one direction.

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“…An impactful class of active anisotropic fluids is based on reconstituted cytoskeletal elements, wherein the active stresses are generated by clusters of molecular motors that step along multiple filaments, driving their relative sliding (17,18). So far, the focus has been on quantifying the chaotic dynamics of cytoskeletal active matter in both the nematic and isotropic phases and methods of controlling their autonomous flows through boundaries and confinement (19)(20)(21)(22)(23)(24)(25)(26). However, being reconstituted from well-defined biochemical components, these systems provide a unique, yet so far largely unexplored, opportunity to elucidate the microscopic origins of the emergent chaotic dynamics, thus paving the way for developing predictive multiscale models (27)(28)(29).…”

mentioning

confidence: 99%

Active liquid crystals powered by force-sensing DNA-motor clusters

Tayar

Hagan

Dogic

2021

Proc. Natl. Acad. Sci. U.S.A.

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Cytoskeletal active nematics exhibit striking nonequilibrium dynamics that are powered by energy-consuming molecular motors. To gain insight into the structure and mechanics of these materials, we design programmable clusters in which kinesin motors are linked by a double-stranded DNA linker. The efficiency by which DNA-based clusters power active nematics depends on both the stepping dynamics of the kinesin motors and the chemical structure of the polymeric linker. Fluorescence anisotropy measurements reveal that the motor clusters, like filamentous microtubules, exhibit local nematic order. The properties of the DNA linker enable the design of force-sensing clusters. When the load across the linker exceeds a critical threshold, the clusters fall apart, ceasing to generate active stresses and slowing the system dynamics. Fluorescence readout reveals the fraction of bound clusters that generate interfilament sliding. In turn, this yields the average load experienced by the kinesin motors as they step along the microtubules. DNA-motor clusters provide a foundation for understanding the molecular mechanism by which nanoscale molecular motors collectively generate mesoscopic active stresses, which in turn power macroscale nonequilibrium dynamics of active nematics.

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Confinement Controls the Bend Instability of Three-Dimensional Active Liquid Crystals

Cited by 55 publications

References 65 publications

Active microphase separation in mixtures of microtubules and tip-accumulating molecular motors

Active microphase separation in mixtures of microtubules and tip-accumulating molecular motors

Spontaneous circulation of active microtubules confined by optical traps

Active liquid crystals powered by force-sensing DNA-motor clusters

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