Aromatic–Aromatic Interactions Enable α-Helix to β-Sheet Transition of Peptides to Form Supramolecular Hydrogels

[Image: see text] Isolated short peptides usually are unable to maintain their original secondary structures due to the lack of the restriction from proteins. Here we show that two complementary pentapeptides from a β-sheet motif of a protein, being connected to an aromatic motif (i.e., pyrene) at their C-terminal, self-assemble to form β-sheet like structures upon mixing. Besides enabling the self-assembly to result in supramolecular hydrogels upon mixing, aromatic–aromatic interactions promote the pentapeptides transform from α-helix to β-sheet conformation. As the first example of using aromatic–aromatic interactions to mimic the conformational restriction in a protein, this work illustrates a bioinspired way to generate peptide nanofibers with predefined secondary structures of the peptides by a rational design using protein structures as the blueprint.