Shear-induced gelation of self-yielding active networks

Abstract

Molecular-motor generated active stresses drive the cytoskeleton away from equilibrium, endowing it with tunable mechanical properties that are essential for diverse functions such as cell division and motility[1-5]. Designing analogous biomimetic systems is a key prerequisite for creating active matter that can emulate cellular functions[6-7]. These long-term goals requires understanding of how motor-generated stresses tune the mechanics of filamentous networks[8-11]. In microtubule-based active matter, kinesin motors generate extensile motion that leads to persistent breaking and reforming of the network links[12]. We study how such microscopic dynamics modifies the network's mechanical properties, uncovering that the network viscosity first increases with the imposed shear rate before transitioning back to a low-viscosity state. The non-monotonic shear-dependent viscosity can be controlled by tuning the speed of molecular motors. A two-state phenomenological model that incorporates liquid- and solid-like elements quantitatively relates the non-monotonic shear-rate-dependent viscosity to locally-measured flows. These studies show that rheology of extensile networks are different from previously studied active gels[13], where contractility enhances mechanical stiffness. Moreover, the flow induced gelation is not captured by continuum models of hydrodynamically interacting swimmers[14-21]. Observation of activity-dependent viscoelasticity necessitates the development of models for self-yielding of soft active solids whose intrinsic active stresses fluidize or stiffen the network.

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Cited by in corpus (8)

• Dynamics of active liquid interfaces
• Confinement controlled bend instability of three-dimensional active fluids
• Extensile to contractile transition in active microtubule-actin composites generates layered asters with programmable lifetimes
• Data-driven discovery of active nematic hydrodynamics
• Self-mixing in microtubule-kinesin active fluid from nonuniform to uniform distribution of activity
• Active restructuring of cytoskeleton composites leads to increased mechanical stiffness, memory, and heterogeneity
• Dynamic Flow Control Through Active Matter Programming Language
• Interfacial instability of confined 3D active droplets