Tunable hydrogel morphology via self-assembly of amphiphilic pentablock copolypeptides

Hydrogels assembled from symmetric amphiphilic pentablock copolypeptides were investigated using rheology and cryogenic transmission electron microscopy (cryoTEM). Due to the presence of two alpha-helical hydrophobic segments per chain, the pentablocks have the potential for organized intrachain folding, akin to natural proteins, in addition to intermolecular assembly. We found that variation of the central hydrophilic segment lengths in the copolymers enabled precise tuning of assembly morphology and hydrogel properties. CryoTEM characterization revealed that the hydrogels are nanoporous networks composed of branched and entangled tape-like fibrils, where average fibril length varied with the length of hydrophilic spacer between the hydrophobic domains. The pentablock architecture in these copolymers thus allowed additional control over self-assembled morphology and substantial enhancement of hydrogel properties.