title: Novel Displacement Agents for Aqueous 2-Phase Extraction Can Be Estimated Based on Hybrid Shortcut Calculations.
abstract: The purification of therapeutic proteins is a challenging task with immediate need for optimization. Besides other techniques, aqueous 2-phase extraction (ATPE) of proteins has been shown to be a promising alternative to cost-intensive state-of-the-art chromatographic protein purification. Most likely, to enable a selective extraction, protein partitioning has to be influenced using a displacement agent to isolate the target protein from the impurities. In this work, a new displacement agent (lithium bromide [LiBr]) allowing for the selective separation of the target protein IgG from human serum albumin (represents the impurity) within a citrate-polyethylene glycol (PEG) ATPS is presented. In order to characterize the displacement suitability of LiBr on IgG, the mutual influence of LiBr and the phase formers on the aqueous 2-phase system (ATPS) and partitioning is investigated. Using osmotic virial coefficients (B22 and B23) accessible by composition gradient multiangle light-scattering measurements, the precipitating effect of LiBr on both proteins and an estimation of both protein partition coefficients is estimated. The stabilizing effect of LiBr on both proteins was estimated based on B22 and experimentally validated within the citrate-PEG ATPS. Our approach contributes to an efficient implementation of ATPE within the downstream processing development of therapeutic proteins.
authors.affiliation: Department of Biochemical and Chemical Engineering, Laboratory of Thermodynamics, Technische Universität Dortmund, Dortmund, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Kress
authors.affiliation: Department of Biochemical and Chemical Engineering, Laboratory of Thermodynamics, Technische Universität Dortmund, Dortmund, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Sadowski
authors.affiliation: Department of Biochemical and Chemical Engineering, Laboratory of Thermodynamics, Technische Universität Dortmund, Dortmund, Germany. Electronic address: christoph.brandenbusch@bci.tu-dortmund.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Brandenbusch
mesh_terms: D001965:Bromides / Q000737:chemistry* / Q000494:pharmacology; D011232:Chemical Precipitation / Q000187:drug effects; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D059625:Liquid-Liquid Extraction / Q000379:methods*; D018020:Lithium Compounds / Q000737:chemistry* / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000737:chemistry / Q000494:pharmacology; D014867:Water / Q000737:chemistry*
chemical_list: D001965:Bromides; D007074:Immunoglobulin G; D018020:Lithium Compounds; D014867:Water; D011092:Polyethylene Glycols; C040949:lithium bromide
keywords: IgG antibody; albumin; light scattering (static); partition coefficient; precipitation; thermodynamics