Intracellular protein motors have evolved to perform specific tasks critical to the function of cells such as intracellular trafficking and cell division1,2. Kinesin and dynein motors, for example, transport cargoes in living cells by walking along microtubules powered by adenosine triphosphate hydrolysis3,4. These motors can make discrete 8 nm centre-of-mass steps and can travel over 1 µm by changing their conformations during the course of adenosine triphosphate binding, hydrolysis and product release5,6. Inspired by such biological machines, synthetic analogues have been developed including self-assembled DNA walkers that can make stepwise movements on RNA/DNA substrates7,8,9,10,11,12 or can function as programmable assembly lines13. Here, we show that motors based on RNA-cleaving DNA enzymes14 can transport nanoparticle cargoes—CdS nanocrystals in this case—along single-walled carbon nanotubes. Our motors extract chemical energy from RNA molecules decorated on the nanotubes and use that energy to fuel autonomous, processive walking through a series of conformational changes along the one-dimensional track. The walking is controllable and adapts to changes in the local environment, which allows us to remotely direct ‘go’ and ‘stop’ actions. The translocation of individual motors can be visualized in real time using the visible fluorescence of the cargo nanoparticle and the near-infared emission of the carbon-nanotube track. We observed unidirectional movements of the molecular motors over 3 µm with a translocation velocity on the order of 1 nm min−1 under our experimental conditions.
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The authors thank H.N. Robinson and M.C. Akatay for help with synthesis and TEM characterization of CdS nanocrystals. This work was supported by the US Office of Naval Research (awards N00014-11-1-0220 and N00014-12-1-0829). J.H.C. acknowledges a National Science Foundation Career award.
The authors declare no competing financial interests.
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Cha, TG., Pan, J., Chen, H. et al. A synthetic DNA motor that transports nanoparticles along carbon nanotubes. Nature Nanotech 9, 39–43 (2014). https://doi.org/10.1038/nnano.2013.257
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