Atomic-precision π-driven peptide hydrogel nanofibers with ordered water channels.

Aromatic interactions organize molecules into ordered supramolecular architectures, while peptides form functional soft materials through hydrogen bonding and water-mediated assembly. In peptide-based systems, strong aromatic stacking is typically achieved by terminal capping, whereas terminally uncapped peptides organize water through polar end groups but rarely form highly ordered materials. Here we show that a π-extended aromatic unit can be integrated into a terminally uncapped peptide to create a class of supramolecular hydrogels with structural order. A pyrene-modified dipeptide hierarchically assembles into monodisperse helical nanofibers and self-healing hydrogels. Cryo-electron microscopy resolves the nanofibers at near-atomic precision (1.7 Å), revealing tightly packed protofilaments, continuous ordered water channels, and a unidirectional dipole extending along the fiber. These results demonstrate how reinforced aromatic stacking, polar interactions, and cooperative water organization can be orchestrated to generate emergent electrostatics and mechanical resilience, bridging conjugated materials and biomolecular matter, enabling functional soft materials inaccessible to either domain alone.