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Free-floating ultrathin two-dimensional crystals from sequence-specific peptoid polymers

Nature Materials volume 9, pages 454–460 (2010)Cite this article

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Abstract

The design and synthesis of protein-like polymers is a fundamental challenge in materials science. A biomimetic approach is to explore the impact of monomer sequence on non-natural polymer structure and function. We present the aqueous self-assembly of two peptoid polymers into extremely thin two-dimensional (2D) crystalline sheets directed by periodic amphiphilicity, electrostatic recognition and aromatic interactions. Peptoids are sequence-specific, oligo-N-substituted glycine polymers designed to mimic the structure and functionality of proteins. Mixing a 1:1 ratio of two oppositely charged peptoid 36mers of a specific sequence in aqueous solution results in the formation of giant, free-floating sheets with only 2.7 nm thickness. Direct visualization of aligned individual peptoid chains in the sheet structure was achieved using aberration-corrected transmission electron microscopy. Specific binding of a protein to ligand-functionalized sheets was also demonstrated. The synthetic flexibility and biocompatibility of peptoids provide a flexible and robust platform for integrating functionality into defined 2D nanostructures.

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Figure 1: Two-dimensional crystalline sheets formed from two oppositely charged peptoid polymers.
Figure 2: Imaging of 2D crystalline sheets assembled from periodic amphiphilic peptoid polymers.
Figure 3: Direct observation of peptoid chains using aberration- corrected TEM (TEAM 0.5).
Figure 4: Characterization of sheets and sheet-formation kinetics.
Figure 5: Sheet-formation kinetics and mechanism.
Figure 6: Specific protein binding to functionalized sheets.

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Acknowledgements

We thank P. Ashby, S. Whitelam and J. Schmit for helpful discussions and S. Yakovlev and K. Downing for help with electron diffraction. We acknowledge J. Holton and G. Meigs for all of their support at beamline 8.3.1 and E. Schaible and A. Hexemer for solution X-ray scattering experiments at beamline 7.3.3 at the Advanced Light Source and Claire Woo for grazing-incidence XRD data. This work was carried out at the Molecular Foundry, the National Center for Electron Microscopy and the Advanced Light Source at Lawrence Berkeley National Laboratory, all of which are supported by the Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contract No. DE-AC02—05CH11231. L.T. and P.H.C. were supported by the Defense Threat Reduction Agency (IACRO-B0845281).

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Authors and Affiliations

  1. Molecular Foundry,

    Ki Tae Nam, Sarah A. Shelby, Philip H. Choi, Amanda B. Marciel, Ritchie Chen, Li Tan, Tammy K. Chu, Ryan A. Mesch, Byoung-Chul Lee, Michael D. Connolly & Ronald N. Zuckermann

  2. National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

    Christian Kisielowski

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Contributions

K.T.N. and R.N.Z. designed research and wrote the paper. K.T.N., S.A.S., A.B.M., P.H.C., R.C. and L.T. carried out analytical experiments. T.K.C., R.A.M, B-C.L. and M.D.C. carried out chemical synthesis. C.K. carried out the aberration-corrected TEM. All authors discussed the results and commented on the manuscript. R.N.Z. guided all aspects of the work.

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Correspondence to Ronald N. Zuckermann.

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Nam, K., Shelby, S., Choi, P. et al. Free-floating ultrathin two-dimensional crystals from sequence-specific peptoid polymers. Nature Mater 9, 454–460 (2010). https://doi.org/10.1038/nmat2742

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