Reversible Hydrogels from Self-Assembling Artificial Proteins

TLDR

Artificial proteins engineered with terminal leucine‑zipper domains and a central polyelectrolyte segment self‑assemble into coiled‑coil aggregates that form a reversible three‑dimensional network, dissolving when pH or temperature rises. The ability to trigger gelation and dissolution under mild, near‑neutral pH and ambient temperature conditions makes these hydrogels promising for bioengineering applications such as encapsulation and controlled release of molecules and cells.

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.