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. In peptide-based systems, aromatic stacking is usually achieved by terminal capping, but here the authors show that a π-extended aromatic unit can be integrated into an uncapped peptide using a pyrene-modified dipeptide that assembles into monodisperse helical nanofibers and forms hydrogels. Cryo-electron microscopy resolves the nanofibers at near-atomic resolution, revealing their tightly packed supramolecular architecture and continuous ordered water channels.