De Novo Design of a Shear-Thin Recoverable Peptide-Based Hydrogel Capable of Intrafibrillar Photopolymerization

A de novo designed peptide-based gel has been prepared whose mechanical rigidity can be modulated after shear-thin recovery. The photopolymerizable β-hairpin peptide named MLD undergoes temperature-induced folding and self-assembly to afford a network of β-sheet-rich fibrils that constitutes a moderately rigid hydrogel (G′ = 220 ± 50 Pa, 1 wt %). The MLD hydrogel can be shear-thinned into a low-viscosity gel upon application of shear stress and immediately recovers its mechanical rigidity upon termination of stress. MLD peptides contain non-natural sorbamide derivatives of lysine that allow the mechanical rigidity of its hydrogels to be enhanced through polymerization of dienes displayed along the surface of the fibrils constituting the gel. Irradiation of the gel network increases its mechanical rigidity ∼2.5-fold. Circular dichroism (CD) spectroscopy shows that MLD folds and self-assembles into β-sheet-rich fibrils and that photo-cross-linking does not influence the secondary structure contained within the assembly. The MLD hydrogel shows potential as an injectable material whose mechanical properties can be modulated after delivery.