Ion exchange–based membrane chromatography has already proven to be a powerful alternative to polishing columns in flow-through
mode for contaminant removal. More recently, new membrane adsorbers have been designed for use in other applications. This
article discusses a Sartobind phenyl membrane adsorber that has been developed for the manufacturing-scale production of biomolecules
based on hydrophobic interaction chromatography (HIC) principles. The new adsorptive membrane combines the advantages of membrane
chromatography with a high binding capacity for proteins comparable to that of conventional HIC resins. It represents a new
tool for downstream processing, applicable for both bind-and-elute and flow-through operations.
In the past decade, there has been a trend in the biopharmaceutical industry toward higher upstream productivity, i.e., higher
cell culture titers, to meet the ever-growing clinical and commercial demand.1 This trend poses a challenge for the industry—to develop and scale-up downstream purification processes capable of purifying
multiple kilograms per batch. Although downstream processing faces significant bottlenecks because of heavy reliance on traditional
bead-based chromatography.2,3 For example, although Protein A chromatography has undergone great optimization for throughput in the past five years, the
expected rise in cell culture titers, combined with the need for larger masses of antibodies, indicates a need for further
improvement of the existing Protein A resin to accommodate the demand for high-throughput production.4 Therefore, there has been significant interest in the development of new technologies that facilitate the processing of
multikilogram batches at the lowest possible cost.2,5 Among the novel technologies developed, membrane chromatography has a high potential, particularly for process-scale monoclonal
antibody (MAb) purification.
Sartorius Stedim Biotech
Membranes feature a more open structure than resins, so there is virtually no diffusion limitation, and as a result they
offer many technical advantages that have been well described in the literature.6–9 Several applications have been discussed for MAb purification. Because of the generally high isoelectric points of MAbs,
anion exchange (AEX) resins are typically used as a polishing step in a flow-through mode (i.e., the product does not bind
while the trace impurities such as DNA, viruses, endotoxins, and host cell proteins are retained).10 Although the amount of impurities to bind is very low in such operations, conventional polishing scale-up leads to column
oversizing because of the pressure and diffusion limitations associated with conventional bead-based chromatography. In contrast,
a disposable membrane chromatography device has a convective mode of mass transport, which allows operation at significantly
higher linear flow-rates (shorter residence times) than columns. As a result, disposable membrane chromatography device can
have a much smaller volume than that of a conventional column when used in flow-through mode. This significantly reduces buffer
consumption, processing time, and floor space requirements.11 Sartobind ion exchange capsules, for example, have been successfully implemented in various downstream processes for the
removal of negatively charged contaminants.12–15 It is well documented in the literature that AEX membrane adsorbers are a powerful alternative to columns and can facilitate
the development of new purification strategies for downstream processing.
In addition to positively charged membranes, hydrophobic interaction membrane chromatography (HIC) has been described for
the purification of a humanized MAb.16 Hydrophobic interaction is listed among the most commonly used chromatography methods for protein purification. For MAb
purification, HIC is also often operated in flow-through mode.10 It is used to separate molecules based on their difference in hydrophobicity, and the technique has been presented as an
efficient mode to remove dimers and high molecular weight (HMW) aggregates as a polishing step in a MAb purification process.17 In this article, we describe the use of an HIC membrane adsorber for the purification of a monoclonal IgG1 expressed using
the PER.C6 human cell line. The hydrophobic membrane adsorber is based on hydrophilic regenerated stabilized cellulose with
hydrophobic phenyl groups covalently attached to the base matrix.