Reversible Hydrogels from Self-Assembling Artificial Proteins

Abstract

Recombinant DNA methods were used to create artificial proteins that undergo reversible gelation in response to changes in pH or temperature. The proteins consist of terminal leucine zipper domains flanking a central, flexible, water-soluble polyelectrolyte segment. Formation of coiled-coil aggregates of the terminal domains in near-neutral aqueous solutions triggers formation of a three-dimensional polymer network, with the polyelectrolyte segment retaining solvent and preventing precipitation of the chain. Dissociation of the coiled-coil aggregates through elevation of pH or temperature causes dissolution of the gel and a return to the viscous behavior that is characteristic of polymer solutions. The mild conditions under which gel formation can be controlled (near-neutral pH and near-ambient temperature) suggest that these materials have potential in bioengineering applications requiring encapsulation or controlled release of molecular and cellular species.

Manipulation of hydrogel assembly and growth factor delivery via the use of peptide–polysaccharide interactions

“…Among them, poly (glycolic acid) and poly (lactic acid) have been applied very frequently, but they can form proinflammatory fragments as a result of the acidic byproducts of their degradation. Noncovalent systems, such as those based on protein-protein interactions between antibodies and antigens [30] as well as others [31][32][33]56,57], have been explored and offer opportunities for the application of injectable delivery systems with controlled properties. However, less attention has been given to the interaction between peptides and other molecules in hydrogel assembly.…”

“…In addition, noncovalent crosslinking strategies may offer advantages in maintaining protein integrity and bioactivity until delivery. Polymer hydrogels have been formed via specific recognition events such as reversible antibody-antigen interactions [30] and coiled-coil interactions [31][32][33]. There has been less attention given, however, to the interaction between peptides (particularly coiledcoils) and polysaccharides in hydrogel assembly.…”

Localized adenovirus gene delivery using antiviral IgG complexation

“…[11][12][13][14][15] In recent years, sustained release preparations for the deliv- plexation approach, and ganciclovir was added to rat smooth muscle cells (A10) in culture with the gels. With complexed HSVtk adenovirus, only cells either in contact with the viruscontaining gel or within 50 m were killed.…”

Self‐assembly and responsiveness of polypeptide‐based block copolymers: How “Smart” behavior and topological complexity yield unique assembly in aqueous media

“…108,111 At higher concentrations, these systems often form network structures from the association of corona chains between micelles resulting in hydrogelation. 107,109,110,112,113 A few studies have been devoted to self-assembly of coil-rod-coil BAB triblock copolymers containing a functionalized, hydrophilic gold nanorod center FEATURE ARTICLE block and hydrophobic coil outer blocks. [114][115][116] This category of amphiphilic molecules exhibited self-assembly into ''doughnut-like" supramolecular barrels (similar to toroid micelles), as a result of stiffness from the center block.…”