IgG and hybridoma partitioning in aqueous two-phase systems containing a dye-ligand

The effect of the important ATPS- and buffer parameters on IgG and hybridoma partitioning in ATPSs containing a PEG-dye-ligand was studied. Objective was to establish selection criteria for effective ligands for extractive fermentations with animal cells in ATPSs. In the presence of 1% PEG-dye-ligand the binding of IgG to the PEG-ligand was affected severely by the Na-chloride concentration. The tie-line length and pH affected IgG partitioning to a lesser extent. The desired partitioning of IgG into the top phase, was only obtained when, in addition to the 10 mmol/kg K-phosphate buffer, no Na-chloride was present. In an ATPS culture medium, with +/- 35 mmol/kg Na-bicarbonate and 60 mmol/kg Na-chloride, increasing the PEG-dye-ligand concentration up to 100% did increase the partition coefficient, but was not effective in concentrating the IgG in the top phase of ATPS culture medium at a pH of 7.8. Furthermore, addition of the PEG-dye-ligand to ATPS culture medium changed the hybridoma cell partitioning from the bottom phase to the interface.