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Mechanical pressure produces atomically-precise, multifunctional 2D sheets

A few months ago the use of designed peptides to build supramolecular structures on surfaces was reported. Another group has now reported making two-dimensional atomically precise sheets using peptoids, a class of peptide mimetics in which the side chain is attached to the backbone nitrogen atom instead of to the alpha carbon atom. Such sheets might be useful as templates for assembling other nanostructures. A hat tip to Science Daily for reprinting this news release from the Lawrence Berkeley National Laboratory (Berkeley Lab) “Shaken, not stirred: Berkeley Lab scientists spy molecular maneuvers“:

Stir this clear liquid in a glass vial and nothing happens. Shake this liquid, and free-floating sheets of protein-like structures emerge, ready to detect molecules or catalyze a reaction. This isn’t the latest gadget from James Bond’s arsenal—rather, the latest research from the U. S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) scientists unveiling how slim sheets of protein-like structures self-assemble. This “shaken, not stirred” mechanism provides a way to scale up production of these two-dimensional nanosheets for a wide range of applications, such as platforms for sensing, filtration and templating growth of other nanostructures.

“Our findings tell us how to engineer two-dimensional, biomimetic materials with atomic precision in water,” said Ron Zuckermann, Director of the Biological Nanostructures Facility at the Molecular Foundry, a DOE nanoscience user facility at Berkeley Lab. “What’s more, we can produce these materials for specific applications, such as a platform for sensing molecules or a membrane for filtration.”

Zuckermann, who is also a senior scientist at Berkeley Lab, is a pioneer in the development of peptoids, synthetic polymers that behave like naturally occurring proteins without degrading. His group previously discovered peptoids capable of self-assembling into nanoscale ropes, sheets and jaws, accelerating mineral growth and serving as a platform for detecting misfolded proteins.

In this latest study, the team employed a Langmuir-Blodgett trough — a bath of water with Teflon-coated paddles at either end — to study how peptoid nanosheets assemble at the surface of the bath, called the air-water interface. By compressing a single layer of peptoid molecules on the surface of water with these paddles, said Babak Sanii, a post-doctoral researcher working with Zuckermann, “we can squeeze this layer to a critical pressure and watch it collapse into a sheet.”

“Knowing the mechanism of sheet formation gives us a set of design rules for making these nanomaterials on a much larger scale,” added Sanii. …

The research was published in the Journal of the American Chemical Society (JACS) [abstract]. It will be interesting to see if these peptoid nanosheets can be developed to provide atomically precise surfaces on which other components can be assembled in a defined atomically precise arrangement, as can be done with DNA origami.

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