  Engineering synthetic materials that mimic the remarkable complexity of
living organisms is a fundamental challenge in science and technology. We study
the spatiotemporal patterns that emerge when an active nematicfilm 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
highlight 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.
