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A charge-driven molecular water pump


Understanding and controlling the transport of water across nanochannels is of great importance for designing novel molecular devices, machines and sensors and has wide applications1,2,3,4,5,6,7,8,9, including the desalination of seawater5. Nanopumps driven by electric or magnetic fields can transport ions10,11 and magnetic quanta12, but water is charge-neutral and has no magnetic moment. On the basis of molecular dynamics simulations, we propose a design for a molecular water pump. The design uses a combination of charges positioned adjacent to a nanopore and is inspired by the structure of channels in the cellular membrane that conduct water in and out of the cell (aquaporins). The remarkable pumping ability is attributed to the charge dipole-induced ordering of water confined in the nanochannels13,14, where water can be easily driven by external fields in a concerted fashion. These findings may provide possibilities for developing water transport devices that function without osmotic pressure or a hydrostatic pressure gradient.

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Figure 1: Introduction to the main system and the flows and fluxes for different charge arrangements in the main system.
Figure 2: Water–charge interaction and the averaged dipole orientation of water molecules inside the SWNT.


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We thank P. A. Pincus, D. Bensimon, Ruhong Zhou, Chunhai Fan and Jun Yan for helpful discussions. This work was supported by grants from Chinese Academy of Sciences, the National Science Foundation of China under grants nos. 10474109 and 10674146, the National Basic Research Program of China under grant nos. 2007CB936000, 2006CB933000 and 2006CB708612, and Shanghai Supercomputer Center of China.

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Authors and Affiliations



X.J.G. performed most of the numerical simulations. H.P.F. and X.J.G. carried out most of the theoretical analysis. J.Y.L., H.J.L. and R.Z.W. carried out some numerical simulations and theoretical analysis. H.P.F., J.H., X.J.G. and J.C.L. contributed most of the ideas and wrote the paper. All authors discussed the results and commented on the manuscript.

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Correspondence to Jun Hu or Haiping Fang.

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Gong, X., Li, J., Lu, H. et al. A charge-driven molecular water pump. Nature Nanotech 2, 709–712 (2007).

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