Pharmaceutical Research

, Volume 25, Issue 3, pp 674–682

Genetically Engineered Block Copolymers: Influence of the Length and Structure of the Coiled-Coil Blocks on Hydrogel Self-Assembly

Research Paper

DOI: 10.1007/s11095-007-9343-z

Cite this article as:
Xu, C. & Kopeček, J. Pharm Res (2008) 25: 674. doi:10.1007/s11095-007-9343-z

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.

Key words

coiled-coilsgenetically engineered polymershydrogelsself-assembly

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  1. 1.Department of Pharmaceutics and Pharmaceutical ChemistryUniversity of Utah Salt Lake CityUSA
  2. 2.Department of BioengineeringUniversity of Utah Salt Lake CityUSA