Extensile to contractile transition in active microtubule–actin composites generates layered asters with programmable lifetimes

Abstract

SignificanceActive forces sculpt the forms of living things, generating adaptable and reconfigurable dynamical materials. Creating synthetic materials that exhibit comparable control over internally generated active forces remains a challenge. We demonstrate that active composite networks, collectively driven by the force-generating molecular motors, exhibit complex spatiotemporal patterns similar to those observed in cell biology. Amongst others, we describe robust self-assembly of onion-like layered asters. A self-regulating mechanism ensures the asters’ layered structure survives coalescence-like events, while their temporal stability is encoded in the mechanical properties of the network. Our model system elucidates the essential role of passive elasticity in controlling the emergent nonequilibrium dynamics while also establishing a robust experimental platform for engineering lifelike materials.