DNA-Controlled Spatiotemporal Patterning of a Cytoskeletal Active Gel

Abstract

Living cells move and change their shape because signaling chemical reactions modify the state of their cytoskeleton, an active gel that converts chemical energy into mechanical forces. To create life-like materials, it is thus key to engineer chemical pathways that drive active gels. Here we describe the preparation of DNA-responsive surfaces that control the activity of a cytoskeletal active gel composed of microtubules: A DNA signal triggers the release of molecular motors from the surface into the gel bulk, generating forces that structure the gel. Depending on the DNA sequence and concentration, the gel forms a periodic band pattern or contracts globally. Finally, we show that the structuration of the active gel can be spatially controlled in the presence of a gradient of DNA concentration. We anticipate that such DNA-controlled active matter will contribute to the development of life-like materials with self-shaping properties.

Crosslinking and depletion determine spatial instabilities in cytoskeletal active matter

“…In summary, this work provides a unified view of spatial instabilities in cytoskeletal active gels and provides an experimental and theoretical framework to design active materials with controllable out-of-equilibrium properties. 19,[34][35][36] 4 Materials and methods…”

Self-mixing in microtubule-kinesin active fluid from nonuniform to uniform distribution of activity

“…The success of the diffusion-limited model suggests that the active transport in the active fluid systems studied above is dominated by diffusion. This inspires us to question whether the progression of active-inactive interface will become superdiffusion-like when the active transport becomes convection-like 27 , 28 . To answer this question, we varied experimental parameters to explore a wider range of fluid flow speeds.…”

Self-mixing in microtubule-kinesin active fluid from nonuniform to uniform distributions of activities

“…With this in mind, we developed a second hypothesis: the mixing of active and inactive fluids is governed by an active fluid-induced superdiffusion-like process only when the flow-speed level of the active fluid is sufficiently high. 27,28 To test this hypothesis, we performed the same experiments while varying the flow-speed level of the active fluid in the initial UV-activated region, quantified as the average of flow speeds in the bulk of the initially activated area, . Because the interface progression could be affected by ATP concentrations (Fig.…”

“…Active systems with nonuniform but stationary activity exhibit dynamics distinct from those with uniform activity. [27][28][29][30][31][32][33] These dynamics become particularly rich when activity varies in space and time 31,32 and the evolution of the activity field couples to the active flow. [27][28][29] However, such mixing dynamics with complex coupling between activity field and active flow remains poorly understood.…”

“…[27][28][29][30][31][32][33] These dynamics become particularly rich when activity varies in space and time 31,32 and the evolution of the activity field couples to the active flow. [27][28][29] However, such mixing dynamics with complex coupling between activity field and active flow remains poorly understood. To study fluid and mixing dynamics in a system with nonuniform activity and spatiotemporally coupled activity distribution and fluid flow, we investigated how activated active fluid mixed and blended with inactivated active fluid until the system reached a uniform state and employed active nematohydrodynamic and mass-transport models to describe the mixing process.…”