This presentation will describe our latest research efforts on devising improved methods to capture and purify antibodies from cell culture supernatant using overload and elute chromatography with newly designed multimodal membranes (MMMs). The membranes incorporate ligands that can bind proteins through a combination of Coulombic interactions, hydrophobic interactions, and/or hydrogen bonding, thus widening the operation ranges for separation and improving selectivity.
Protein binding experiments with IgG show the MMM has a high equilibrium binding capacity (180 mg IgG/ml) and excellent salt tolerance. The multimodal membranes maintain binding capacities in excess of 100 mg IgG/ml at salt concentrations that are typical for elution buffers used in multi-stage chromatographic bioseparation processes. Protein dynamic binding capacities in excess of 50 mg IgG/ml were determined from breakthrough curve analysis.
The MMMs were used as the stationary phase following a Protein A purification step in the purification human IgG1 from Chinese hamster ovary (CHO) cell culture supernatant. The MMM stationary phase greatly enhanced load productivity compared to resin-based ion-exchange media. Further, no buffer exchange step was required between the Protein A and MMM chromatography purification steps.
In a second study, the MMMs were used as the stationary phase for the primary capture step, in place of Protein A resin chromatography. Using an overload and elute chromatography process, the MMMs demonstrated a high selectivity for capturing human IgG from CHO cell culture supernatant. A high quality protein product was obtained from the MMM chromatography purification step.
This work shows that the new MMM chromatography operation can effectively decrease the number of purification steps and shorten the purification time and/or increase load productivity in downstream processing of biologics.