Engineering
synthetic materials that mimic the remarkable complexity of living organisms is a fundamental challenge in science and
technology. We studied the spatiotemporal patterns that emerge when an active nematic film of
microtubules and molecular motors is encapsulated within a shape-changing lipid vesicle.
Unlike in equilibrium systems, where
defects are largely static structures, in active nematics defects move spontaneously and can be described as self-propelled
particles. The combination of activity, topological constraints, and vesicle
deformability produces a myriad of dynamical states. We quantitatively
described two dynamical modes: a tunable periodic state that oscillates between
two defect configurations, and shape-changing vesicles with streaming filopodia-like protrusions. These results
demonstrate how biomimetic materials can be obtained
when topological constraints are used to control the non-equilibrium dynamics
of active matter.
3D
reconstruction of an
active nematic vesicle. Motile defect oscillate
between planar
and tetrahedra configuration.
Tuning
vesicle tension through
osmotic stress
induces formation
of four fillopodia-like
structures.
