(97c) Capture of a Monoclonal Antibody from a Fungal Culture Fluid Using Chromatographic Nonwoven Membranes

Downstream processing of mAbs faces the challenges of increasing production efficiency while reducing costs. The mAb Protein A capture step is the costliest of the all the steps in the traditional mAb purification platform. Inexpensive nonwoven membranes show great promise as disposable chromatographic media due to their low pressure drops at high flow rates, excellent scalability, flexible, rapid production as well as high binding capacity after functionalization with ligands. In this work, a cation exchange (CEX) nonwoven, a multimodal cation exchange (MMC) nonwoven and a multimodal anion exchange (MMA) nonwoven were applied to capture of a monoclonal antibody from a fungal culture fluid. These three chromatographic membranes were developed by conjugating with sulfonic acid (-SO₃), multimodal ligands—2-mercaptopyridine-3-carboxylic acid (MPCA) and N-benzyl-N-methylethanolamine (BMEA)—onto the poly (glycidyl methacrylate) grafted nonwoven membrane, and their robust binding performance for antibodies were validated over 15 consecutive bind-and-elute cycles using pure human polyclonal antibody with DBC₁₀_% greater than 50 mg/mL at 0.5 min residence time. Pre-treatment methods including depth filtration, dextran coated charcoal and dilution were investigated to assess the impact of pigments and salt constituents in the fungal culture fluid on mAb purification by the membranes. Salt concentration and composition, such as the presence of EDTA and MgSO₄ in the culture fluid, appeared to be the primary factors contributing to early mAb breakthrough during sample loading process. This adverse impact can be effectively mitigated by optimizing the pH and conductivity of the equilibration buffers. The performance of the three nonwoven membranes was compared under the same conditions including loading volume, membrane bed volume, and residence time. The CEX membranes outperformed the MMA membrane in terms of mAb recovery and purity in the eluate. This was attributed to reduced competitive binding from impurities, as most host cell proteins (pI 3.5–5.5) and DNA are acidic and passed through the CEX membranes during loading. In preliminary studies, the MMA-MPCA membrane achieved a high recovery of 95.7% and a purity of 81.2% in the mAb capture step.