Protein-Based Aqueous−Multiphasic Systems

This paper reports the formation of aqueous-multiphasic systems (AMPS) exclusively made using elastin-like polypeptides (ELP) which have the ability to undergo reversible inverse phase transitions. Manipulating variables such as the salt concentration and the molecular weight and the composition of ELPs (using different amino acid sequences or by fusing the ELP with different functional proteins) permits modulation of the temperature at which phase transition takes place, the number of phases that are formed, and the composition of the multiple aqueous phases. Using these variables, isotropic hybrid colloids with tunable functionality (in this case, fluorescent intensity) and anisotropic colloids with variable morphologies could be generated. While formation of AMPS and anisotropic colloids has been reported in the literature using synthetic polymers, to our knowledge this is the first report of generating such systems using proteins.