Rapid identification of tailor-made aqueous two-phase systems for the extractive purification of high-value biomolecules

The industrial production of high-value biomolecules, such as monoclonal antibodies or industrially applicable enzymes (used as biocatalysts), has grown significantly within the last decades. Aqueous two-phase extraction (ATPE) using an aqueous two-phase system (ATPS) has long been shown to be a promising alternative to cost-intensive chromatography for purification of these potent biomolecules. However, state-of-the-art ATPS design is still based on trial-and-error screening approaches identifying un-optimized ATPS that often perform below requirements. Within this work, an optimized and enhanced method for the identification of a tailor-made ATPS for the AWE of high-value biomolecules is presented. Through thermodynamic modeling using the ePC-SAFT equation-of-state, a first choice in phase-former candidates can be identified based on their molecular interactions in solution, leading to optimal water conditions for the biomolecule. Simultaneously, the conformational stability in presence of the phase-former candidates is investigated by measuring the unfolding temperature of the biomolecule to refine this selection. The aggregation propensity is estimated by determining the second osmotic virial coefficient B-22, thus the colloidal stability of the biomolecule is taken into account. Based on these results, the partition coefficient of the biomolecule as well as a process window for the AWE can be estimated. This method was applied to immunoglobulin G (IgG) and allows for a selection of phase-formers offering optimal working conditions regarding stability and minimized aggregation propensity. Moreover, a process window concerning temperature and phase-former concentration for the ATPE was defined allowing for a selective IgG purification. (C) 2020 Elsevier B.V. All rights reserved.