Anisotropic structures made by hierarchical self-assembly and crystallization play an essential role in the living system. However, the spontaneous formation of liquid crystalline hydrogel of low molecular weight organic molecules with controlled properties remains challenging. This work describes a rational design of two complementary charged tetrapeptides with the alternating feature of nonpolar aromatic phenylalanine (F) and charged amino acids (glutamic acid (E), lysine (K), or arginine (R)) that utilizes intermolecular interactions to drive the formation of nanofiber bundles in a two-component system (<b>Ac-FEFE + Ac-FKFK</b> or <b>Ac-FEFE + Ac-FRFR</b>), which could not access by a single component. The diameter of nanofibers can be simply controlled by varying the enantiomer of electrostatic pairs. Mutation of K to R results in an over 30-fold increase of mechanical property. Mechanistic studies unravel the mechanism of self-assembly and formation of anisotropic liquid crystalline domains. All-atom molecular dynamics simulations reveal that the mixture of heterochiral peptides self-assembles into nanofiber with larger width compared to the homochiral assemblies due to the different stacking pattern and intermolecular interactions. The intermolecular interactions show an obvious increase by substituting the K with R, facilitating a more stable assembly and further altering the assembly mechanics and bulk material properties. The liquid crystalline hydrogel generated from isotropic monomers would provide a potential application in different areas, including tissue engineering, materials sciences, and regenerative medicine.

Biomimetic heterodimerization of tetrapeptides to generate liquid crystalline hydrogel in a two-component system

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