Active materials are capable of converting free energy into mechanical work to produce autonomous motion, and exhibit striking collective dynamics that biology relies on for essential functions. Controlling those dynamics and transport in synthetic systems has been particularly challenging. Here, we introduce the concept of spatially structured activity as a means of controlling and manipulating transport in active nematic liquid crystals consisting of actin filaments and light-sensitive myosin motors. Simulations and experiments are used to demonstrate that topological defects can be generated at will and then constrained to move along specified trajectories by inducing local stresses in an otherwise passive material. These results provide a foundation for the design of autonomous and reconfigurable microfluidic systems where transport is controlled by modulating activity with light.
Subscribe to Journal
Get full journal access for 1 year
only $17.42 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
All experimental image data are available on the Dryad server (https://doi.org/10.5061/dryad.7wm37pvr6). Additional data are available upon request.
Ramaswamy, S. The mechanics and statistics of active matter. Annu. Rev. Condens. Matter Phys. 1, 323–345 (2010).
Marchetti, M. C. et al. Hydrodynamics of soft active matter. Rev. Mod. Phys. 85, 1143–1189 (2013).
Vicsek, T. Novel type of phase transition in a system of self-driven particles. Phys. Rev. Lett. 75, 1226–1229 (1995).
Sokolov, A., Mozaffari, A., Zhang, R., de Pablo, J. J. & Snezhko, A. Emergence of radial tree of bend stripes in active nematics. Phys. Rev. X 9, 031014 (2019).
Saw, T. B. et al. Topological defects in epthelia govern cell death and extrusion. Nature 544, 212–216 (2017).
Kawaguchi, K., Kageyama, R. & Sano, M. Topological defects control collective dynamics in neural progenitor cell cultures. Nature 545, 327–331 (2017).
Bricard, A., Caussin, J., Desreumaux, N., Dauchot, O. & Bartolo, D. Emergence of macroscopic directed motion in populations of motile colloids. Nature 503, 95–98 (2013).
Kumar, N., Soni, H., Ramaswamy, S. & Sood, A. K. Flocking at a distance in active granular matter. Nat. Commun. 5, 4688 (2014).
Dombrowski, C., Cisneros, L., Chatkaew, S., Goldstein, R. E. & Kessler, J. O. Self-concentration and large-scale coherence in bacterial dynamics. Phys. Rev. Lett. 93, 098103 (2004).
Li, H. et al. Data-driven quantitative modeling of bacterial active nematics. Proc. Natl Acad. Sci. USA 116, 777–785 (2019).
Vizsnyiczai, G. et al. Light controlled 3D micromotors powered by bacteria. Nat. Commun. 8, 15974 (2017).
Needleman, D. & Dogic, Z. Active matter at the interface between materials science and cell biology. Nat. Rev. Mater. 2, 17408 (2017).
Sanchez, T., Chen, D. T. N., DeCamp, S. J., Heymann, M. & Dogic, Z. Spontaneous motion in hierarchically assembled active matter. Nature 491, 431–434 (2012).
Wensink, H. H. et al. Meso-scale turbulence in living fluids. Proc. Natl Acad. Sci. USA 109, 14308–14313 (2012).
Giomi, L., Bowick, M. J., Mishra, P., Sknepnek, R. & Marchetti, M. C. Defect dynamics in active nematics. Phil. Trans. A 372, 20130365 (2014).
Zhou, S., Sokolov, A., Lavrentovich, O. D. & Aranson, I. S. Living liquid crystals. Proc. Natl Acad. Sci. USA 111, 1265–1270 (2014).
Ellis, P. W. et al. Curvature-induced defect unbinding and dynamics in active nematic toroids. Nat. Phys. 14, 85–90 (2018).
Keber, F. C. et al. Topology and dynamics of active nematic vesicles. Science 345, 1135–1139 (2014).
Guillamat, P., Ignés-Mullol, J. & Sagués, F. Control of active liquid crystals with a magnetic field. Proc. Natl Acad. Sci. USA 113, 5498–5502 (2016).
Wu, K. et al. Transition from turbulent to coherent flows in confined three-dimensional active fluids. Science 355, eaal1979 (2017).
Opathalage, A. et al. Self-organized dynamics and the transition to turbulence of confined active nematics. Proc. Natl Acad. Sci. USA 116, 4788–4797 (2019).
Duclos, G., Yashunsky, V., Salbreux, G., Joanny, J. & Prost, J. Spontaneous shear flow in confined cellular nematics. Nat. Phys. 14, 728–732 (2018).
de Gennes, P. G. & Prost, J. The Physics of Liquid Crystals (Clarendon Press, 1993).
Giomi, L., Bowick, M. J., Ma, X. & Marchetti, M. C. Defect annihilation and proliferation in active nematics. Phys. Rev. Lett. 110, 228101 (2013).
Giomi, L. Geometry and topology of turbulence in active nematics. Phys. Rev. X 5, 031003 (2015).
Doostmohammadi, A., Ignés-Mullol, J. & Yeomans, J. M. Active nematics. Nat. Commun. 9, 3246 (2018).
Kumar, N., Zhang, R., de Pablo, J. J. & Gardel, M. L. Tunable structure and dynamics of active liquid crystals. Sci. Adv. 4, eaat7779 (2018).
Thampi, S. P., Golestanian, R. & Yeomans, J. M. Velocity correlations in an active nematic. Phys. Rev. Lett. 111, 118101 (2013).
Zhang, R., Kumar, N., Ross, J. L., Gardel, M. L. & de Pablo, J. J. Interplay of structure, elasticity, and dynamics in actin-based nematic materials. Proc. Natl Acad. Sci. USA 115, E124–E133 (2018).
Kinosita, K. et al. Dual-view microscopy with a single camera: real-time imaging of molecular orientations and calcium. J. Cell Biol. 115, 67–73 (1991).
Sase, I., Miyata, H., Ishiwata, S. & Kinosita, K. Axial rotation of sliding actin filaments revealed by single-fluorophore imaging. Proc. Natl Acad. Sci. USA 94, 5646–5650 (1997).
Nakamura, M. et al. Remote control of myosin and kinesin motors using light-activated gearshifting. Nat. Nanotechnol. 9, 693–697 (2014).
Ruijgrok, P. V. et al. Optical control of fast and processive engineered myosins in vitro and in living cells. Nat. Chem. Biol. (in the press).
Ross, T. D. et al. Controlling organization and forces in active matter through optically defined boundaries. Nature 572, 224–229 (2019).
Linsmeier, I. et al. Disordered actomyosin networks are sufficient to produce cooperative and telescopic contractility. Nat. Commun. 7, 12615 (2016).
Schindler, T. D., Chen, L., Lebel, P., Nakamura, M. & Bryant, Z. Engineering myosins for long-range transport on actin filaments. Nat. Nanotechnol. 9, 33–38 (2014).
Beris, A. N. & Edwards, B. J. Thermodynamics of Flowing Systems: with Internal Microstructure (Oxford Univ. Press, 1994).
Marenduzzo, D., Orlandini, E., Cates, M. & Yeomans, J. Steady-state hydrodynamic instabilities of active liquid crystals: hybrid lattice Boltzmann simulations. Phys. Rev. E 76, 031921 (2007).
Aditi Simha, R. & Ramaswamy, S. Hydrodynamic fluctuations and instabilities in ordered suspensions of self-propelled particles. Phys. Rev. Lett. 89, 058101 (2002).
Zhang, R., Zhou, Y., Rahimi, M. & de Pablo, J. J. Dynamic structure of active nematic shells. Nat. Commun. 8, 13483 (2016).
Shankar, S. & Marchetti, M. C. Hydrodynamics of active defects: from order to chaos to defect ordering. Phys. Rev. X 9, 041047 (2019).
Shen, M., Li, H. & Olvera de la Cruz, M. Surface polarization effects on ion-containing emulsions. Phys. Rev. Lett. 119, 138002 (2017).
Thampi, S. P., Golestanian, R. & Yeomans, J. M. Instabilities and topological defects in active nematics. Europhys. Lett. 105, 18001 (2014).
Burov, S. et al. Distribution of directional change as a signature of complex dynamics. Proc. Natl Acad. Sci. USA 110, 19689–19694 (2013).
Spudich, J. A. & Watt, S. The regulation of rabbit skeletal muscle contraction. I. Biochemical studies of the interaction of the tropomyosin-troponin complex with actin and the proteolytic fragments of myosin. J. Biol. Chem. 246, 4866–4871 (1971).
Palmgren, S., Ojala, P. J., Wear, M. A., Cooper, J. A. & Lappalainen, P. Interactions with PIP2, ADP-actin monomers, and capping protein regulate the activity and localization of yeast twinfilin. J. Cell Biol. 155, 251–260 (2001).
Ito, K., Yamaguchi, Y., Yanase, K., Ichikawa, Y. & Yamamoto, K. Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin. Proc. Natl Acad. Sci. USA 106, 21585–21590 (2009).
Sun, D., Roth, S. & Black, M. J. Secrets of optical flow estimation and their principles. In Proc. IEEE Conf. on Computer Vision and Pattern Recognition 2432–2439 (IEEE, 2010).
Landau, L. D. & Lifshitz, I. M. Statistical Physics (Butterworth-Heinemann, 1980).
Denniston, C., Orlandini, E. & Yeomans, J. M. Lattice Boltzmann simulations of liquid crystal hydrodynamics. Phys. Rev. E 63, 056702 (2001).
Denniston, C., Marenduzzo, D., Orlandini, E. & Yeomans, J. M. Lattice Boltzmann algorithm for three-dimensional liquid-crystal hydrodynamics. Phil. Trans. A 362, 1745–1754 (2004).
Guo, Z. & Shu, C. Lattice Boltzmann Method and Its Applications in Engineering (World Scientific Publishing Company, 2013).
Guo, Z., Zheng, C. & Shi, B. Discrete lattice effects on the forcing term in the lattice Boltzmann method. Phys. Rev. E 65, 046308 (2002).
R.Z. and A.M. are grateful to The University of Chicago Research Computing Center for assistance with the calculations carried out in this work. This work is primarily supported by The University of Chicago Materials Research Science and Engineering Center, which is funded by the National Science Foundation (NSF) under award DMR-2011854. J.J.d.P. acknowledges support from NSF grant DMR-1710318. The calculations presented here were performed on the GPU cluster supported by the NSF under grant DMR-1828629. N.K. acknowledges the Yen Fellowship of the Institute for Biophysical Dynamics, The University of Chicago. Z.B. acknowledges support from NIH R01 GM114627 and a W. M. Keck Foundation grant to Z.B. and M. Prakash. M.L.G. acknowledges support from NSF Grant DMR-1905675 and NIH GM104032.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Video legends 1–9, Figs. 1–10, Table 1 and discussion.
Active nematic with time varying activity. Time-lapse fluorescence images of liquid crystal with conditions detailed in Supplementary Table 1. To stimulate motor gear shifting, the sample was illuminated with a 491 nm laser across the entire field of view in addition to imaging wavelengths. Stimulated frames are indicated with ‘Light on' in the upper left-hand corner.
Active nematic with spatially varying activity. Time-lapse fluorescence images of liquid crystal with conditions detailed in Supplementary Table 1. To stimulate motor gear shifting in only one portion of the sample, a 470 nm LED was targeted to only the region outlined by the red box using a digital micromirror array for the duration of the video (see Methods).
Simulations of flat interface showing that a +½ defect (highlighted in a red circle) originally nucleated in an active region (red shadowed) and straying into a passive region is eventually attracted back to the active region.
Simulations of defect generation using a rectangular pattern. Two pairs of defects are generated, followed by complex motion, annihilation and regeneration of defects.
Simulations of defect generation using a triangular pattern. A single pair of defects arises from the asymmetric activity pattern.
Simulations of a pair of ±½ defects. Annihilation for uniform activity α/α0 = 0.2 showing that the +½ defect moves along its symmetry axis and eventually annihilates the −½ defect.
Active nematic with spatially directed defect motion. Time-lapse fluorescence images of liquid crystal with conditions detailed in Supplementary Table 1. To stimulate motor gear shifting a 470 nm LED was targeted to only the quarter-annulus region outlined in red using a digital micromirror array (see Methods). The defect centre is indicated with a blue dot while the tail indicates the defect path since the start of the experiment. Replicate 1.
Simulations show that the annulus pattern can constrain and guide the +½ defect, supporting the experimental observation that activity patterns can guide the defect.
Simulations of defect pathways in a ‘H' channel using two different activity patterns, showing that the activity pattern is able to guide defect pathways through a microfluidic device.
About this article
Cite this article
Zhang, R., Redford, S.A., Ruijgrok, P.V. et al. Spatiotemporal control of liquid crystal structure and dynamics through activity patterning. Nat. Mater. (2021). https://doi.org/10.1038/s41563-020-00901-4