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Pharm Res. 2008 Mar;25(3):674-82. Epub 2007 Aug 23.

Genetically engineered block copolymers: influence of the length and structure of the coiled-coil blocks on hydrogel self-assembly.

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  • 1Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 30 S. 2000 E. Rm. 201, Salt Lake City, Utah 84112, USA.

Abstract

PURPOSE:

To explore the relationship between the structure of block polypeptides and their self-assembly into hydrogels. To investigate structural parameters that influence hydrogel formation and physical properties.

METHODS:

Three ABA triblock and two AB diblock coiled-coil containing polypeptides were designed and biologically synthesized. The triblock polypeptides had two terminal coiled-coil (A) domains and a central random coil (B) segment. The coiled-coil domains were different in their lengths, and tyrosine residues were incorporated at selected solvent-exposed positions in order to increase the overall hydrophobicity of the coiled-coil domains. The secondary structures of these polypeptides were characterized by circular dichroism and analytical ultracentrifugation. The formation of hydrogel structures was evaluated by microrheology and scanning electron microscopy.

RESULTS:

Hydrogels self-assembled from the triblock polypeptides, and had interconnected network microstructures. Hydrogel formation was reversible. Denaturation of coiled-coil domains by guanidine hydrochloride (GdnHCl) resulted in disassembly of the hydrogels. Removal of GdnHCl by dialysis caused coiled-coil refolding and hydrogel reassembly.

CONCLUSIONS:

Protein ABA triblock polypeptides composed of a central random block flanked by two coiled-coil forming sequences self-assembled into hydrogels. Hydrogel formation and physical properties may be manipulated by choosing the structure and changing the length of the coiled-coil blocks. These self-assembling systems have a potential as in-situ forming depots for protein delivery.

PMID:
17713844
[PubMed - indexed for MEDLINE]
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