Development of Multimodal Membrane Adsorbers for Protein Separations

This presentation will describe our latest research efforts using surface engineering to develop multimodal membranes as a new class of high-productivity chromatographic materials for applications in the purification of therapeutic proteins. Multimodal membranes incorporate ligands that can bind proteins through a combination of Coulombic interactions, hydrophobic interactions, and/or hydrogen bonding. This advancement has the potential to widen the operation ranges for chromatographic separations. In addition, the high-productivity nature of this membrane platform will help to alleviate the tradeoff that manufacturers must now make between load processing time and dynamic binding capacity.

Membranes were prepared using surface-initiated ATRP (atom transfer radical polymerization) of poly(glycidyl methacrylate) ‘tentacles’ from regenerated cellulose membranes. In a second step, 4-mercaptobenzoic acid was coupled to the membranes by an epoxide ring-opening reaction. ATR-FTIR measurements were carried out to support successful ligand incorporation. Protein binding experiments with bovine immunoglobulin G showed that binding capacities of the multimodal membranes were dependent on pH and ionic strength. A maximum binding capacity above 60 mg IgG/mL was found near the isoelectric point of the protein. The capacity remained above 30 mg IgG/mL even at 300 mM ionic strength.