Conjugated surfactant micelles: A non-denaturing purification platform for concentrated human immunoglobulin G

As downstream purification and separation technologies progress towards raising the concentration of therapeutic-grade monoclonal antibodies (mAbs) in cell culture, downstream processing has begun to face increased difficulty in efficiently coping with such high immunoglobulin G (IgG) titers (≤25 mg mL⁻¹). In the current study, we demonstrate the ability of a non-chromatographic, ligand-free procedure to recover almost quantitatively (84–99% yield, by densitometry) polyclonal, human IgG present at high concentrations (15–25 mg mL⁻¹⁾ in E. coli lysate. Instead of chromatographic media and columns, we use conjugated, mixed-micelles comprising non-ionic detergents, tyrosine monomers, and the amphiphilic [(bathophenanthroline)3:Fe²⁺] complex. Capture and extraction processes are performed at pH 6.5–7, thereby avoiding antibody exposure to acidic, potentially denaturing conditions. Recovered IgG is monomeric as determined by dynamic light scattering (DLS). Process upscaling from 0.1 to 5 mL requires only proportional increase in all reagents and does not affect overall yield or antibody purity.