Micro- and nanostructures fabricated from biological building blocks have attracted tremendous attention owing to their potential for application in biology and in nanotechnology. Many biomolecules, including peptides and proteins, can interact and self-assemble into highly ordered supramolecular architectures with functionality. By imitating the processes where biological peptides or proteins are assembled in nature, one can delicately design and synthesize various peptide building blocks composed of several to dozens of amino acids for the creation of biomimetic or bioinspired nanostructured materials. This tutorial review aims to introduce a new kind of peptide building block, the diphenylalanine motif, extracted with inspiration of a pathogenic process towards molecular self-assembly. We highlight recent and current advances in fabrication and application of diphenylalanine-based peptide nanomaterials. We also highlight the preparation of such peptide-based nanostructures as nanotubes, spherical vesicles, nanofibrils, nanowires and hybrids through self-assembly, the improvement of their properties and the extension of their applications.

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Organogels that are self-assembled from simple peptide molecules are an interesting class of nano- and mesoscale soft matter with simplicity and functionality. Investigating the precise roles of the organic solvents and their effects on stabilization of the formed organogel is an important topic for the development of low-molecular-weight gelators. We report the structural transition of an organogel self-assembled from a single dipeptide building block, diphenylalanine (L-Phe-L-Phe, FF), in toluene into a flower-like microcrystal merely by introducing ethanol as a co-solvent; this provides deeper insights into the phase transition between mesostable gels and thermodynamically stable microcrystals. Multiple characterization techniques were used to reveal the transitions. The results indicate that there are different molecular-packing modes formed in the gels and in the microcrystals. Further studies show that the co-solvent, ethanol, which has a higher polarity than toluene, might be involved in the formation of hydrogen bonds during molecular self-assembly of the dipeptide in mixed solvents, thus leading to the transition of organogels into microcrystals. The structural transformation modulated by the co-solvent might have a potential implication in controllable molecular self-assembly.