Tunable elastic solids assembled by an active fluid

Living systems harness active stress to generate diverse structures and dynamical states that are not feasible in equilibrium materials. To understand how active flows can shape passive networks, we study a composite system in which a network of actin filaments is assembled and actuated by a microtubule-based active fluid. In turn, the emerging elastic network generates resistance to microtubule-based flows. Local extensile stresses drive network reconfiguration across several length and time scales. By tuning active stress and network stiffness through motor and crosslinker concentration, respectively, we described distinct kinetic pathways by which the microtubules reshape the actin network. Our work demonstrates how active fluids can assemble diverse network architectures that are not accessible using conventional methods and materials processing schemes.