Disulfide crosslinking and helical coiling of peptide micelles facilitate the formation of a printable hydrogel

We report that the helical coiling of micelles induced by disulfide crosslinking in a lyotropic peptide liquid crystal leads to the formation of a printable hydrogel. The (9-fluorenylmethyloxycarbonyl)protected phenylalanine-phenylalanine-cysteine tripeptide could firstly self-assemble into aligned micelles at high pH values via noncovalent interactions, leading to the formation of a viscous solution. Intriguingly, the cross-linking of the sulfhydryl group between the peptides changed greatly the rheological properties of the peptide solutions, leading to a 6500-fold increase of the storage modulus to 39 kPa. This led to the formation of a self-supporting peptide hydrogel with a series of improved physical properties, including shear-thinning and thixotropy. The formation of the peptide hydrogels with enhanced physical properties can be attributed to the structural transition of the parallelly aligned worm-like micelles into coiled nanohelices induced by the cross-linking of disulfide bonding. The findings deepen our understanding on the relationship between micelle chirality and gel properties, and provide a strategy to fabricate highly functional materials via simultaneous noncovalent and covalent polymerizations.