Separation of immunoglobulin G using aqueous biphasic systems composed of cholinium‐based ionic liquids and poly(propylene glycol)

Abstract

Background The use of antibodies, such as immunoglobulin G (IgG), has faced a significant growth in the past decades for biomedical and research purposes. However, antibodies are high cost biopharmaceuticals, for which the development of alternative and cost-effective purification strategies is still in high demand. Results Aqueous biphasic systems (ABS) composed of poly(propylene glycol) (PPG) and cholinium-based ionic liquids (ILs) were investigated for the separation of IgG. The ABS phase diagrams were determined and characterized whenever required. Initial optimization studies with commercial IgG were carried out, followed by the extraction of IgG from rabbit serum. In all ABS, IgG preferentially partitions to the IL-rich phase, unveiling preferential interactions between IgG and ILs. Good results were obtained with commercial IgG, with extraction efficiencies ranging between 93% and 100%, and recovery yields ranging between 20% and 100%. Two of the best and two of the worst identified ABS were then evaluated in what concerns their performance to separate and recover IgG from rabbit serum. With these ABS, extraction efficiencies of 100% and recovery yields > 80% were obtained, indicating an increase in the recovery yield and extraction efficiencies when using real matrices. Under the best conditions studied, IgG with a purity level of 49% was obtained in a single-step. This purity level of IgG is higher than those previously reported using other IL-polymer ABS. Conclusion IgG preferentially migrates to the IL-rich phase in ABS formed by ILs and polymers, allowing the design of effective separation systems for its recovery from serum samples.

Selective and mild fractionation of microalgal proteins and pigments using aqueous two‐phase systems

“…Other studies explained the effect of protein structure (e.g. surface amino acid residues) on the partitioning of these molecules using ATPSs formed by polymer and ILs . Concluding that protein partitioning depends on specific interactions (e.g.…”

“…surface amino acid residues) on the partitioning of these molecules using ATPSs formed by polymer and ILs. 35,58 Concluding that protein partitioning depends on specific interactions (e.g. electrostatic) between the protein and the IL.…”

“…Besides that, proteins recovered in the interface seem to conserve their native conformation based on electrophoresis experiments and pigments did not suffer oxidation in the top phase. Recovery of the proteins in the bottom phase and recycle of the cholinium dihydrogen phosphate for reuse is possible by ultrafiltration as described by Ramalho et al 58 A large number of biocompatible ILs such as Ch-DHp are being synthetized, 60 which opens up research opportunities for polymer-IL ATPSs. This type of ATPS and their recyclability will be studied in the future to separate microalgae biomolecules in an integrated biorefinery approach.…”

Is Bioseparation still the limiting step in bioprocess development?

“…Finally, the research papers of this Special Issue present selected advances in the field of primary recovery, purification and bioprocess development . Examples from the primary recovery of products include: a new method to extract recombinant intracellular GFP from E. coli by using aqueous solutions of surface‐active compounds, a novel integrated bioseparation process for the in situ recovery of L‐asparaginase from fermentation broth, a stable and efficient flocculation method associated with depth filtration for continuous cell separation and an approach using ultrafiltration for whey protein separation .…”

“…The development of a high‐gradient magnetic fishing process for recovery of immunoglobulins from unclarified antiserum and the potential for application of colloidal gas aphrons fractions from grape extracts in cosmetics are nicely described as alternative techniques for product recovery. From the particular field of ATPS using ionic liquids, the primary recovery of; sinomenine from Sinomenium acutum , immunoglobulin G and levodopa are critically discussed. These examples further raise the recent trends of the application of ATPS in the bioseparation field.…”