title: Refolding hydrogels self-assembled from N-(2-hydroxypropyl)methacrylamide graft copolymers by antiparallel coiled-coil formation.
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.
authors.affiliation: Department of Pharmaceutics, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Jiyuan
authors.initials: J
authors.lastname: Yang
authors.forename: Chunyu
authors.initials: C
authors.lastname: Xu
authors.forename: Chun
authors.initials: C
authors.lastname: Wang
authors.forename: Jindrich
authors.initials: J
authors.lastname: Kopecek
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D019281:Dimerization; D020100:Hydrogels / Q000138:chemical synthesis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010316:Particle Size; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013696:Temperature
chemical_list: D003432:Cross-Linking Reagents; D020100:Hydrogels; D010446:Peptide Fragments; D011109:Polymethacrylic Acids; C011533:Duxon