Bigels formed via spinodal decomposition of unfolded protein.

Bigels (or double network gels) are an emerging class of tuneable soft materials characterized by two discrete but interpenetrating gel networks in which both networks contribute to the physical and mechanical properties of the material. We describe, for the first time, the formation of a bigel network from two different proteins. By careful control of solution conditions, kinetics and specific protein chemistry the inter-species interactions in the two protein system are weak compared with the intra-protein attraction, which leads to bigel formation. The resulting protein bigel has an elastic modulus four times greater than the combined elastic moduli of the parent gels, has an elastic response over several deformation cycles and is both thermo- and chemo-responsive. These gels have the potential to be used as biomimetics in tissue culture, in drug delivery or for biomedical applications such as wound healing.