We present a new class of bioinspired nanomaterials that are stabilized by a combination of covalent and hydrogen bonds. Prior work by others has shown that cyclic peptides can self-assemble to form supramolecular assemblies through backbone-backbone hydrogen bonding. To improve upon this molecular architecture, we develop a synthesis route to polymerize cyclic peptides and form a linear polymer chain that can transition between a rigid nanorod and a “soft” unfolded conformation. For a cyclic peptide polymer containing an amine-terminated side chains on each ring, we demonstrate self-assembly can be triggered in aqueous solutions by varying the pH. We measure the elastic modulus of the rigid nanorods to be ca. 50 GPa, which is comparable to our molecular dynamics (MD) prediction (ca. 64 GPa). Also, through MD simulations, we explore how the effect of varying the cyclic peptide size and the length of the linkage between cyclic peptides on the mechanical properties of the nanorods. Our results highlight the uniqueness of our molecular architecture, namely their exemplary toughness (up to 3 GJ m<sup>-3</sup>), in comparison to other cyclic peptide-based assemblies.<br/>

Design principles of extremely tough cyclic peptide polymers

256th National Meeting (2018)

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