Self-assembling peptide fibres are recognized as versatile supramolecular scaffolds of biomaterials. For example, peptide amphiphiles bearing fatty acid chains at a terminus of the peptide main chain construct nanofibres by forming cylindrical micelles. Diphenylalanine has also been extensively studied as a backbone to afford supramolecular fibres. 11,12 Such supramolecular peptide fibres provide three-dimensional networks with a gelation capability as ideal scaffold materials for mimicking and controlling the bio-interface between cells due to their advantages such as easy preparation, surface tunability, and biocompatibility. Of them, peptides consisting of repeating sequences of RADA (Arg-Ala-Asp-Ala) such as RADA16 15 are also known to form supramolecular nanofibres in aqueous media through β-sheet-type hydrogen bonding and hydrophobic interaction corresponding to the alternating sequence of hydrophilic and hydrophobic amino acid residues. Since RADA-based peptides are composed of naturally occurring amino acids, they can also be used as a tag sequence incorporated into proteins of interest with an E. coli expression system for binding with the supramolecular nanofibres. In addition, peptide fibres that exhibit various dynamic behaviours can be designed by tuning the amino acid sequences, particularly in the hydrophobic part (Fig. ). For example, it has been reported that the conformational flexibility of peptide fibres can be a critical factor in controlling the stiffness of the hydrogels made of the entangled supramolecular nanofibres. Introducing glycine residues generally enhances the conformational flexibility of polypeptide chains. Despite the enhanced flexibility, A8G, a mutant of RADA16 in which the alanine in the middle of the peptide sequence is replaced with glycine, forms bundled nanofibres and a more robust hydrogel than RADA16 (Fig. ). On the other hand, A16G, in which the terminal alanine residue of RADA16 is replaced with glycine, forms curved fibres seen on transmission electron microscopy (TEM) (Fig. ). Molecular dynamics (MD) simulations also visualized similar self-assembling morphology (Fig. ). The hydrogel made of A16G showed lower stiffness than that of RADA16, suggesting that the morphological differences of the fibres could affect the macroscopic properties. The enhanced mobility with the decreased stiffness and the thixotropic property of A16G hydrogel can be advantageous for injection in biomedical applications.