Non-Chromatographic Antibody Purification Using Aqueous Two-Phase Systems

The continual drive to increase monoclonal antibody cell culture titers has renewed interest in alternative initial capture steps that can replace traditional protein-A chromatography. One promising area is the use of two-phase aqueous systems composed of two polymers or one polymer and one salt, whose properties drive the selective separation of the target molecule into one of the resultant phases. A two-phase aqueous system comprising a mixture of one polymer – polyethylene glycol (PEG) and one salt – Citrate was investigated for the capture and purification of a monoclonal antibody out of clarified conditioned medium. Parameters affecting antibody partition, impurity clearance and the volume ratio (Vr) of the phases formed were identified using a Design of Experiments methodology, and an operating space was established. A complete partitioning of antibody into the PEG phase was observed with an overall recovery of greater than 80% and a product purity of 99%. Bench-scale experiments laid a solid foundation for future scale-up work.