Superior mechanical and optical properties of a heterogeneous library of cross-linked biomimetic self-assembling peptides

Self-assembling peptides (SAP) are ideal components for biomedical devices. However, their practical applications have been limited due to their intrinsic unstable, low-performance, and low-stress response given by non-covalent interactions involved in self-assembling. Herein, a library of SAPs featuring different self-assembled nanostructures was successfully cross-linked with genipin, allowing to produce nanofibrous hydrogels with enhanced mechanical properties (G′ ≥ 0.2 MPa, stress-failure ≥ 3.5 kPa) and enhanced thermostability (≥100 °C) while maintaining their native nanoarchitecture. Cross-linking dramatically changed the optical properties of SAPs: it triggered new absorption/fluorescence bands in the visible spectral range, which are attributed to charge transfer between peptide chains. Genipin cross-linking, fitted for different classes of SAPs, could be a powerful tool to obtain biomimetic SAP scaffolds with tunable stiffness and thermostability. Lastly, because of the changed absorption/emission properties and relaxation kinetics of cross-linked SAPs, genipin cross-linking may bestow novel optical properties to several well-known lysine-containing SAPs, with intriguing potential for biomedical imaging, photonics and optoelectronics.