High-capacity multimodal anion-exchange membranes for polishing of therapeutic proteins

This contribution reports on a study using Purexa (TM)-MQ multimodal anion-exchange (AEX) membranes for protein polishing at elevated solution conductivities. Dynamic binding capacities (DBC10) of bovine serum albumin (BSA), human immunoglobulins, and salmon sperm DNA (ss-DNA) are reported for various salt types, salt concentrations, flowrates, and pH. Using 1 mg/ml BSA, DBC10 values for Purexa (TM)-MQ were >90 mg/ml at conductivities up to 15 mS/cm. The membranes maintained a high, salt-tolerant BSA DBC10 of 89.8 +/- 2.7 (SD) over the course of 100 bind-elute cycles. Polishing studies with acidic and basic monoclonal antibodies at >2 kg/L loads showed that Purexa (TM)-MQ had higher clearance of host cell proteins and aggregate species at high conductivity (13 mS/cm) and in the presence of phosphate than other commercial AEX media. Purexa (TM)-MQ also had a high ss-DNA DBC10 of 50 mg/ml at conductivities up to 15 mS/cm, markedly outperforming other commercial products. In addition to the effectiveness of Purexa (TM)-MQ for protein polishing at elevated solution conductivities, its unusually high binding capacity for ss-DNA indicates potential applications for plasmid DNA purification.