Affinity membranes for antibody purification

The use of membrane adsorbers for the polishing step in protein therapeutics manufacture has evolved into a feasible choice for the biopharmaceutical industry while affinity membrane chromatography for the primary capture is still not implemented due to the limited binding capacity of membranes with respect to chromatography beads. In this work, affinity membranes with improved capacity have been considered as an alternative technology for the capturing step in antibody manufacturing. To this aim affinity membranes have been prepared starting from different membrane supports. Several affinity ligands have been utilized like Protein A [1], the natural ligand of choice for antibodies, as well as synthetic ligands that exhibit affinity for the Fc portion of antibodies [2, 3]. The membranes have been characterized in detail: binding and elution performance were evaluated in batch experiments using pure protein solutions and in particular human IgG, murine IgG and human IgM, while membrane selectivity was evaluated using complex solutions like cell culture supernatant or human and mouse sera. The most promising affinity membranes were extensively tested in dynamic experiments. The effects of operating parameters like feed concentration and flow rate on separation performance like binding capacity, selectivity and process yield have been studied in detail in order to find the optimal conditions for binding and elution steps. The membranes have been used over several complete chromatographic cycles to evaluate the effects of ageing and of membrane regeneration on dynamic binding capacity.