Abstract
Active networks made of biopolymers and motor proteins are valuable
bioinspired systems that have been used in the last decades to study the
cytoskeleton and its self-organization under mechanical stimulation. Different
techniques are available to apply external mechanical cues to such structures.
However, they often require setups that hardly mimic the biological
environment. In our study we use an evaporating sessile multi-component droplet
to confine and mechanically stimulate our active network made of microtubules
and kinesin motor proteins. Due to the well-characterized flow field inside an
evaporating droplet, we can fathom the coupling of the intrinsic activity of
the biological material with the shear stress generated by the flow inside the
droplet. We observe the emergence of a dynamic pattern due to this combination
of forces that vary during the evaporation period. We delineate the role that
the composition of the aqueous environment and the nature of the substrate play
in pattern formation. We demonstrate that evaporating droplets may serve as
bioreactors that supports cellular processes and allows investigation on the
dynamics of membraneless compartments. Such a setup is an original tool for
biological structures to understand the mechanisms underlying the activity of
the cytoskeleton under stress and, on the other hand, to investigate the
potential of such adaptive materials compared to conventional materials.