Despite the utility of immunoaffinity adsorption on the laboratory scale, it has had little application in large- scale downstream processing of therapeutic proteins because available support matrices have poor mechanical properties and immunoaffinity ligands are costly and often deactivate upon exposure to elution conditions. Recently available microporous hollow fiber membranes suitable for bioprocessing promise advantages of high throughput rates and short residence times that may preserve the useful lifetime of labile ligands. The potential of these materials in immunoaffinity separations is untested and principles for design and scaleup undeveloped. The goal of this research is to develop a fundamental understanding of the phenomena that determine the performance of microporous immunoaffinity membranes in protein separations. Membranes will be activated and used to bind three ligands for further study: Protein A, which binds to most immunoglobulins, and two monoclonal antibodies - anti-bovine serum albumin and anti-Factor VIII. The immunoaffinity membranes will be fully characterized in terms of physiochemical properties. Measurements will be made of (1) ligate adsorption and elution breakthrough curves, (2) equilibrium and reaction rate parameters, (3) axial dispersion coefficients, and (4) ligand and ligate localization within the membrane. A theoretical model will be developed, validated by comparison with experimental data, and used in simulations to explore design and optimization. The ability of bound ligand to retain functional activity will be explored with successive adsorption-elution cycles using automated equipment.
