Recent Advances in Protein Extraction Using Ionic Liquid-based Aqueous Two-phase Systems

Since its inception in 2003, ionic liquid (IL)-based aqueous two-phase system (ATPS) has been perceived to give a boost to the application of ATPS in protein separation. Given the green and tunable nature of ILs, the functionality of IL-ATPS can be well designed to suit the specificities required by the bioseparation field. Aside from the conventional imidazolium-based ILs, the types of IL investigated have also expanded to other families of cations (e.g., cholinium, ammonium, phosphonium and guanidinium) and benign anions (e.g., carboxylic acids, amino acids and biological buffers). This review aims to provide a comprehensive assessment of the recent literature targeting the applications of IL-ATPSs in the separation and purification of proteins. Different IL families were addressed in terms of their protein-compatibility, and the applicability of the IL-ATPS formed for the separation of a specific protein of interest. Additionally, the present review highlights the possible directions for future developments.