Interfacial stabilization of aqueous two-phase systems: a review

Abstract

Aqueous two-phase systems (ATPS) are useful in various applications, from purification and separation of biomolecules to wastewater treatment. While they have great utility on their own, there is great interest in discovering how their emulsions, comprising droplets of one aqueous phase dispersed in the other aqueous phase, might be stabilized to enhance their functionality and applications. There are several examples of these systems, but the two most common systems found in the literature are PEG–dextran and complex coacervate ATPS. In this Review, we discuss these systems, their utility, and many different approaches for stabilizing their water/water (w/w) emulsions. We highlight examples wherein interfacial stabilizers such as liposomes, polymers of diverse architectures, colloids of varied shapes and morphologies, and even whole cells have been employed. These stabilization approaches for both PEG–dextran and complex coacervate ATPS are discussed. We conclude with a discussion of the applications of these ATPS and how they can benefit from the creation of corresponding w/w emulsions with stabilized droplets.