Peng Yin*, Hao Yan*, Xiaoju G. Daniell*, Andrew J. Turberfield
†
, John H. Reif*
* Department of Computer Science, Duke University
†
Department of Physics, Clarendon Laboratory, University of Oxford
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DNA nanorobotics
Rotation, open/close extension/contraction mediated by environmental changes
Autonomous, unidirectional motion along an extended linear track
Kinesin
( R. Cross Lab )
Synthetic unidirectional DNA walker that moves autonomously along a linear route over a macroscopic structure ?
(Recent work: non-autonomous DNA walker by Seeman’s group,
Autonomous DNA tweezer by Mao’s group)
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A nanoscale object moving autonomously over a self-assembled microscopic structure has important nano-robotics applications, e.g. serving as a nanoparticle and/or information carrier. Recent successes in self-assembly of
DNA nanostructures provide a solid structural basis to meet this challenge.
However, existing nanoscale synthetic DNA devices are unsuitable for the above purpose: they only exhibit localized non-extensible motions
(open/close, extension/contraction, and reversible rotation), mediated by external environmental changes.
Here we report an experimental construction of unidirectional DNA walker that moves autonomously along a linear DNA track . The self-assembled track contains three anchorages at which the walker, a six-nucleotide DNA fragment, can be attached. At each step the walker is ligated to the next anchorage, then cut from the previous one by a restriction endonuclease. Each cut destroys the previous restriction site and each ligation creates a new site in such a way that the walker cannot move backwards. The device is powered by the hydrolysis of ATP by T4 ligase. The prototype device can be embedded in other self-assembled DNA structures and in principle be extended beyond 3-step operation.
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No B

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No B*

No dimer
Monomer control
Dimer control
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Increase in intensity

In summary, we have designed and constructed a nanoscale device in which an autonomous walker moves unidirectionally along a DNA track, driven by the hydrolysis of ATP. The motion of the walker in principle can be extended well beyond the 3-step system demonstrated here. Discovery of new endonucleases with a larger spacing region between its recognition sequences could lead to walkers of larger sizes. By encoding information into the walker and the anchorages, the device can be extended into a powerful autonomous computing device (and hence an
“intelligent” robotics device
). It is also possible to embed multiple walking devices in a microscopic self-assembled DNA lattice such that each walker moves autonomously along its own programmed route and serves as an information and/or nano-particle carrier . Collectively they would produce a complicated pattern of motion and possibly form a coordinated and sophisticated signaling/transportation network . Nanorobotics systems of this kind would open new horizons in nano-computing, nano-fabrication, nano-electronics, and nano-diagnostics/therapeutics.
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