Dynamic characterization of affinity membranes for monoclonal antibodies purification

Downstream processes for the purification of biological products are often the cost determining production steps. Affinity technology is widely used for the primary capture stage, based on chromatographic beads. In the last decades, significant attention has been devoted to affinity chromatography using microporous membranes as chromatographic supports. Membrane chromatography can overcome the limitation associated to conventional packed-bed columns, such as high pressure drops and slow mass transfer. This work is focused on the purification of Immunoglobulin G (IgG) via affinity membranes. A new support, Sartoepoxy Protein A membranes (Sartorius, Göettingen, Germany) has been tested in detail in dynamic experiments, using pure solutions of polyclonal IgG as well as the supernatant of a fermentation broth containing monoclonal IgG. All the relevant parameters, namely the dynamic binding capacity, process yield and recovery have been evaluated. The influence of several operating parameters on the adsorption and elution performances has been studied to determine the optimal process conditions. A mathematical model including convection, diffusion and multi-component adsorption is proposed to simulate the adsorption, washing and elution steps; the model also considers the possible effects of dead end volumes and flow distribution. Results of the simulation have been compared with the experimental data, giving a good description of the global process.