From Extensile Microtubules Bundles to Synthetic Cilia and Self-Mixing Active Gels

Abstract

In presence of a macromolecular crowding agent filamentous microtubules spontaneously assemble into elongated bundles. Kinesin clusters can simultaneously bind to multiple filaments within such a bundle and thus power relative sliding of the constituent filaments and the overall bundle extension. Starting with such extensile bundles it is possible to hierarchically assemble diverse biologically inspired materials including spontaneously beating synthetic cilia, self-mixing and self-flowing active gels, motile emulsion droplets as well as deformable vesicles. However, little is known about the mechanical properties of isolated active extensile bundles that are the essential structural motif of these diverse materials. We describe an experimental technique that allows us to systematically assemble filamentous bundles with predetermined number of filaments and quantify its ability to generate extensile force.