Spontaneous motion in hierarchically assembled active matter

By Tim Sanchez, Daniel T. N. Chen, Stephen J. DeCamp, Michael Heymann, Z. Dogic. Nature, 2012

1,331 citations recorded by the source corpus.

With remarkable precision and reproducibility, cells orchestrate the cooperative action of thousands of nanometre-sized molecular motors to carry out mechanical tasks at much larger length scales, such as cell motility, division and replication. Besides their biological importance, such inherently non-equilibrium processes suggest approaches for developing biomimetic active materials from microscopic components that consume energy to generate continuous motion. Being actively driven, these materials are not constrained by the laws of equilibrium statistical mechanics and can thus exhibit sought-after properties such as autonomous motility, internally generated flows and self-organized beating. Here, starting from extensile microtubule bundles, we hierarchically assemble far-from-equilibrium analogues of conventional polymer gels, liquid crystals and emulsions. At high enough concentration, the microtubules form a percolating active network characterized by internally driven chaotic flows, hydrodynamic instabilities, enhanced transport and fluid mixing. When confined to emulsion droplets, three-dimensional networks spontaneously adsorb onto the droplet surfaces to produce highly active two-dimensional nematic liquid crystals whose streaming flows are controlled by internally generated fractures and self-healing, as well as unbinding and annihilation of oppositely charged disclination defects. The resulting active emulsions exhibit unexpected properties, such as autonomous motility, which are not observed in their passive analogues. Taken together, these observations exemplify how assemblages of animate microscopic objects exhibit collective biomimetic properties that are very different from those found in materials assembled from inanimate building blocks, challenging us to develop a theoretical framework that would allow for a systematic engineering of their far-from-equilibrium material properties.

Subfields: Cell Biology, Condensed Matter Physics, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/6e23a1cb1d8a34b37cb428b9087c238211e47edb

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Citations in the corpus

Fluid flows created by swimming bacteria drive self-organization in confined suspensions (2014, background): “[11] Sanchez T, Chen DTN, DeCamp SJ, Heymann M, Dogic Z (2012) Spontaneous motion in hierarchically assembled active matter.”
Active Particles in Complex and Crowded Environments (2016, background): “The formation of these patterns seems to be ubiquitous among active matter systems since similar active turbulence has been reported in other active systems on widely varying length and time scales, from suspensions of microtubules, filaments, and molecular motors (Schaller et al., 2010; Sanchez et ”
Geometry and topology of turbulence in active nematics (2014, methodology): “[18] and recently employed by Keber et al.”
Topological active matter (2020, background): “Active ordered fluids have been assembled from a variety of soft materials 5–7, 55 , 56 .”
Hydrodynamics of soft active matter (2013, background): “…interesting property on defects, namely, rotational (Nédélec et al., 1997; Kruse et al., 2005) or translational (Narayan, Ramaswamy, and Menon, 2007; Marchetti, 2012; Sanchez et al., 2012) movement, with sense or direction determined by the chirality or polarity associated with the defect.”
Active suspensions and their nonlinear models (2013, background): “There, large-scale dynamics are seen to arise instead from direct interactions between bio-polymers induced by motor-protein coupling and transport [26] [27] [28], or through interactions with substrate-bound motor-proteins [29] [30].”
Tuned, driven, and active soft matter (2015, background): “These motors can be fixed on a substrate at one end [375, 496] or directly work between the filamental rods [376, 497].”
Active nematics (2018, background): “Prost, Jülicher & Joanny, Active gel physics, Nature Phys 11, 111 (2015) Sanchez et al., Spontaneous motion in hierarchically assembled active matter, Nature 491, 431 (2012) Keber et al., Topology and dynamics of active nematic vesicles, Science 345, 1135 (2014) Beng Saw et al.”
Active Turbulence (2021, background): “The typical force f0 exerted by a single microswimmer on the surrounding fluid can be estimated as f0 ≈ 2πμ0!v0 [55], with a typical bacterial self-propulsion speed v0 ∈ [1,50] μm/s [22].”