PT  - JOURNAL ARTICLE
AU  - Keber, Felix C.
AU  - Loiseau, Etienne
AU  - Sanchez, Tim
AU  - DeCamp, Stephen J.
AU  - Giomi, Luca
AU  - Bowick, Mark J.
AU  - Marchetti, M. Cristina
AU  - Dogic, Zvonimir
AU  - Bausch, Andreas R.
TI  - Topology and dynamics of active nematic vesicles
AID  - 10.1126/science.1254784
DP  - 2014 Sep 05
TA  - Science
PG  - 1135--1139
VI  - 345
IP  - 6201
4099  - http://science.sciencemag.org/content/345/6201/1135.short
4100  - http://science.sciencemag.org/content/345/6201/1135.full
SO  - Science2014 Sep 05; 345
AB  - The orientation of the molecules in a liquid crystalline material will change in response to either changes in the substrate or an external field. This is the basis for liquid crystalline devices. Vesicles, which are fluid pockets surrounded by lipid bilayers, will change size or shape in response to solvent conditions or pressure. Keber et al. report on the rich interactions between nematic liquid crystals placed on the surface of a vesicle. Changes to the vesicle size, for example, can “tune” the liquid crystal molecules. But conversely, the shape of the vesicles can also change in response to the activity of the nematic molecules.Science, this issue p. 1135 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 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.