Membrane Chromatography—An Integrative Concept in the Downstream Processing of Proteins

Membrane chromatography was introduced as an integrative technology for the purification of proteins several years ago. The main feature of chromatographic separations based on membranes is the absence of pore diffusion, which is the main transport resistance in conventional column chromatography using porous particles. This is achieved by attaching the active ligands to the inner surface of the through‐pores of microfiltration membranes, where mass transport takes place mainly by convective flow, thus reducing the transport limitations from pore to film diffusion. In combination with a low pressure drop across a membrane, very high volumetric flows are possible in a membrane‐based purification step; thus, the time requirement of a complete chromatographic cycle is reduced. The method is characterized by fast processing at preserved or even increased resolution compared to standard chromatography on particulate materials. Since its introduction, many successful applications of membrane chromatography have been described. Additionally, theoretical analysis has been performed, which has significantly helped to understand present and visualize future applications of this technology. In this review, the fundamental theoretical considerations from the actual literature are described, and then the applications of membrane‐based separation processes are presented. We have attempted to demonstrate the usefulness of this new technology in the purification of many interesting proteins.