Genetic engineering of self-assembled protein hydrogel based on elastin-like sequences with metal binding functionality.

Recombinant DNA methods have been exploited to enable the creation of protein-based block copolymers with programmable sequences, desired properties, and predictable three-dimensional structures. These advantages over conventional polymer counterparts facilitate the utility of this new class of biomaterials in a wide range of applications. In this project, we exploited the environmental application of protein-based block copolymers based on elastin-like protein (ELP) sequences. Triblock copolymers containing charged and hydrophobic segments were synthesized. Chain lengths of each segment were manipulated in order to maintain a gelation point below room temperature. Polyhistidine sequences were successfully incorporated into the hydrophilic segment without disruption of the self-assembled hydrogel formation. The microscopic structure was further investigated using laser confocal microscopy. The metal binding capability and capacity of resulting hydrogel were studied to demonstrate the functionality of polyhistidine and its environmental application for heavy metal removal. Reversibility of metal binding was demonstrated, indicating the cost-effectiveness of this hydrogel. Significantly, we envision that this versatile strategy of incorporating functional groups within a 3-D protein network provides new possibilities in creation of biomaterials with great control over structure-property relationships.