Proteinaceous fibers with outstanding mechanical properties manipulated by supramolecular interactions

Proteinaceous fibers based on spidroins have attracted widespread attention due to their lightweight and mechanically strong properties. Presently, mechanical modulation is mainly dependent on the ultrahigh molecular weight of recombinant proteins. This makes it difficult to construct and express the target proteins. It is thus significant to develop alternative strategies for the fabrication of robust biological fibers. Herein, we demonstrate one new type of engineered protein fibers using electrostatic complexation of the cationic elastins and anionic dihydroxyphenylalanine surfactants. Interestingly, the mechanical performance of the resulting fibers can be modulated by multiple supramolecular interactions in the system including electrostatic force, hydrogen bonding, metal coordination, cation-π and other aromatic interactions. Consequently, significant alternation of the fibers' breaking strength (from 32 to 160 MPa), Young's modulus (from 0.8 to 17 GPa), and toughness (from 1.2 to 99 MJ·m⁻³) has been achieved. Moreover, the fibers exhibit high plasticity; for example, the formation of different helical structures, and strong fluorescence after the introduction of Tb chelation. Therefore, this study offers new strategies for the mechanical regulation of engineered protein fibers.