A distinguishing feature of living matter is its ability to control force-generating structures that accomplish tasks such as chromosome segregation, intracellular transport, and cell movement. To generate and manipulate these micron-scale structures and force fields , cells create spatiotemporal patterns of molecular-scale activity ] ]  ] . Here, we control micron-scale structures and fluid flow by manipulating molecular-scale protein activity set by dynamic optical boundaries in an engineered system of purified proteins . Our engineered system consists of  microtubules and light-activatable motor proteins that crosslink and URLanize microtubules upon illumination. During URLanization, crosslinked motors do work to create non-equilibrium structures. We design light patternsthat enable us to create, move, and merge microtubule asters with spatial and temporal precision . By composing these basic operations, we  create microtubule networks that can span several hundred microns in length and contract at speeds up to an order of magnitude faster than the speed of an individual motor. By scaling the size and speed of contractile networks , we generate and sculpt advective fluid flows. Our work shows that dynamic boundaries enable control over active matter . The principles of boundary-mediated control we uncover may be used to study emergent cellular structures and forces and to develop programmable active matter devices.
Living systems are capable of locomotion, reconfiguration, and replication. To perform these tasks, cells spatiotemporally coordinate the interactions of force-generating , "active" molecules that create and manipulate non-equilibrium structures and force fields that span up to millimeter length scales 1-3]. Experimental active matter systems of biological or synthetic molecules are capable of URLanizing into structures 4,5] and generating global flows 6-9]. However, these experimental systems lack the spatiotemporal control found in cells, limiting their utility for studying non-equilibrium phenomena and bioinspired engineering . Here, we uncover non-equilibrium phenomena and principles by optically controlling structures and fluid flow in an engineered system of active biomolecules . Our engineered system consists of purified microtubules and light-activatable motor proteins that crosslink URLanize microtubules into distinct structures upon illumination. We develop basic operations, defined as sets of light patterns, to create, move, and merge microtubule structures . By composing these basic operations, we are able to create microtubule networks that span several hundred microns in length and contract at speeds up to an order of magnitude faster than the speed of an individual motor. We manipulate these contractile networks to generate and sculpt persistent fluid flows . The principles of boundary-mediated control we uncover may be used to study emergent cellular structures and forces and to develop programmable active matter devices.
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A distinguishing feature of living matter is its ability to control
Living systems are capable of locomotion, reconfiguration, and replication. To perform these tasks, cells spatiotemporally coordinate the interactions of
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structures that accomplish tasks such as chromosome segregation, intracellular transport, and cell movement. To generate and manipulate these micron-scale
, "active" molecules that create and manipulate non-equilibrium
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, cells create spatiotemporal patterns of molecular-scale activity
that span up to millimeter length scales
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1-3
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. Experimental active matter systems of biological or synthetic molecules are capable of URLanizing into structures
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4,5
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and generating global flows
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6-9
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. However, these experimental systems lack the spatiotemporal control found in cells, limiting their utility for studying non-equilibrium phenomena and bioinspired engineering
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control micron-scale
uncover non-equilibrium phenomena and principles by optically controlling
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by manipulating molecular-scale protein activity set by dynamic optical boundaries
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purified proteins
active biomolecules
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purified
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and URLanize microtubules
URLanize microtubules into distinct structures
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During URLanization, crosslinked motors do work to create non-equilibrium structures. We design light patternsthat enable us
We develop basic operations, defined as sets of light patterns,
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asters with spatial and temporal precision
structures
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are able to
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can
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By scaling the size and speed of contractile networks , we
We manipulate these contractile networks to
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advective fluid flows. Our work shows that dynamic boundaries enable control over active matter
persistent fluid flows