Refolding hydrogels self-assembled from N-(2-hydroxypropyl)methacrylamide graft copolymers by antiparallel coiled-coil formation

Biomacromolecules. 2006 Apr;7(4):1187-95. doi: 10.1021/bm051002k.

Abstract

A novel hybrid hydrogel system based on N-(2-hydroxypropyl)methacrylamide copolymers was proposed. It consisted of the hydrophilic polymer backbone and a pair of oppositely charged peptide grafts. Two distinct pentaheptad peptides (CCE and CCK) were anticipated to create a dimerization motif and serve as physical cross-linkers. Consequently, the graft copolymers CCE-P and CCK-P self-assembled into hybrid hydrogels in situ; the process was modulated by the formation of antiparallel heterodimeric coiled-coils. This approach possesses an advantage to decrease the steric hindrance of the polymer backbone on the "in-register" alignment of peptide grafts. Indeed, equimolar mixtures of the graft copolymers, CCE-P/CCK-P, have been observed to self-assemble into hydrogels in PBS solution at neutral pH at concentrations as low as 0.1 wt %. Circular dichroism spectroscopy, sedimentation equilibrium experiments, and microrheology revealed that the self-assembly process corresponded to the two-stranded alpha-helical coiled-coil formation between CCE and CCK. Moreover, the formation of hybrid hydrogels was reversible. Denaturation of the coiled-coil domains with guanidine hydrochloride (GdnHCl) solutions resulted in disassembly of the hydrogels. Removal of GdnHCl by dialysis caused coiled-coil refolding and hydrogel reassembly. Scanning electron microscopy results demonstrated that the concentration of the graft copolymers had a significant impact on the structure and morphology of self-assembled hydrogels.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cross-Linking Reagents / chemistry
  • Dimerization
  • Hydrogels / chemical synthesis*
  • Hydrogels / chemistry
  • Hydrogen-Ion Concentration
  • Molecular Structure
  • Particle Size
  • Peptide Fragments / chemical synthesis
  • Peptide Fragments / chemistry*
  • Polymethacrylic Acids / chemical synthesis
  • Polymethacrylic Acids / chemistry*
  • Protein Folding*
  • Protein Structure, Secondary
  • Temperature

Substances

  • Cross-Linking Reagents
  • Hydrogels
  • Peptide Fragments
  • Polymethacrylic Acids
  • Duxon