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Artificial water channels enable fast and selective water permeation through water-wire networks

An Author Correction to this article was published on 24 January 2020

This article has been updated

Abstract

Artificial water channels are synthetic molecules that aim to mimic the structural and functional features of biological water channels (aquaporins). Here we report on a cluster-forming organic nanoarchitecture, peptide-appended hybrid[4]arene (PAH[4]), as a new class of artificial water channels. Fluorescence experiments and simulations demonstrated that PAH[4]s can form, through lateral diffusion, clusters in lipid membranes that provide synergistic membrane-spanning paths for a rapid and selective water permeation through water-wire networks. Quantitative transport studies revealed that PAH[4]s can transport >109 water molecules per second per molecule, which is comparable to aquaporin water channels. The performance of these channels exceeds the upper bound limit of current desalination membranes by a factor of ~104, as illustrated by the water/NaCl permeability–selectivity trade-off curve. PAH[4]’s unique properties of a high water/solute permselectivity via cooperative water-wire formation could usher in an alternative design paradigm for permeable membrane materials in separations, energy production and barrier applications.

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Fig. 1: Cluster-forming PAH[4] channels.
Fig. 2: Measurements of water and ion conduction rates through PAH[4]s.
Fig. 3: Intrinsic water/NaCl selectivity (Pw/Ps) versus Pw of PAH[4]-, CNTP- and RsAqpZ-based biomimetic membranes.
Fig. 4: MD simulations of a 22-mer cluster of PAH[4] channels and of an AQP1 tetramer embedded in a lipid bilayer membrane.

Data availability

The datasets that support the finding of this study are available in ScholarSphere repository with the identifier(s) (https://doi.org/10.26207/ykbm-r806).

Change history

  • 24 January 2020

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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Acknowledgements

The authors acknowledge financial support from the National Science Foundation (NSF) CAREER grant (CBET-1552571) to M.K. for this work. A.A. and H.J. acknowledge support from the National Science Foundation under grant DMR-1827346 and the National Institutes of Health under grant P41-GM104601. Additional support was provided by NSF grant CBET-1804836 to M.K. Supercomputer time was provided through XSEDE Allocation Grant no. MCA05S028 and the Blue Waters petascale supercomputer system at the University of Illinois at Urbana−Champaign. H.J. acknowledges the Government of India for the DST-Overseas Visiting Fellowship in Nano Science and Technology.

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W.S., H.J., A.A. and M.K. conceived and designed the research. W.S. and Y.-x.S. performed the experiments with the assistance of J.S.N., C.L., C.B.H., Y.-M.T., M.F., M.E.P. and J.-l.H. in specialized analytical tools. H.J. and R.C. performed the computer simulations. W.S., H.J., R.C., C.D.M., P.S.C., R.J.H., S.A.S., J.-l.H., A.A. and M.K. analysed the data. W.S., H.J., R.C., A.A. and M.K. co-wrote the paper.

Corresponding author

Correspondence to Manish Kumar.

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Peer review information Nature Nanotechnology thanks Andreas Horner, Meni Wanunu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary methods and discussions, Figs. 1–30 and Video captions 1–5.

Supplementary Video 1

Molecular Model of PAH[4] channels. The central constriction of the hybrid[4]arene macromolecules and the nearest phenylalanine moieties are coloured in green. The remaining phenylalanine moieties are coloured in purple.

Supplementary Video 2

Top and cross-sectional views of a MD system featuring a 22-mer cluster (green and purple) of PAH[4] channels embedded in a POPC lipid bilayer membrane (turquoise). For visual clarity, water and ions are not shown.

Supplementary Video 3

A 100 ns long MD simulation trajectory of 22-mer PAH[4] cluster with the ±1 V externally applied bias across the simulation box. In these applied electric field MD simulations, the cluster was harmonically restrained to its equilibrium configuration obtained at the end of a 400 ns-long MD simulation. Lipid bilayer membrane is shown in turquoise, whereas the PAH[4] units are shown in purple and green. Na+ and Cl ions are shown in yellow and blue colour with vdW representation. Water is not shown for clarity.

Supplementary Video 4

MD system featuring a 22-mer cluster (green and purple) of PAH[4] channels embedded in a POPC lipid bilayer membrane (turquoise), showing cooperative water wire network formation spanning the membrane. Water, Na+, and Cl atoms are shown in red and white, magenta, and yellow, respectively.

Supplementary Video 5

Cut-away view of a simulation system illustrating the cooperative water permeation through a water wire network. The 22-mer PAH[4] cluster, POPC lipid membrane, and water molecules are shown in green and purple, turquoise, and red and white, respectively.

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Song, W., Joshi, H., Chowdhury, R. et al. Artificial water channels enable fast and selective water permeation through water-wire networks. Nat. Nanotechnol. 15, 73–79 (2020). https://doi.org/10.1038/s41565-019-0586-8

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