PROTEIN-A IMMUNOAFFINITY HOLLOW-FIBER MEMBRANES FOR IMMUNOGLOBULIN-G PURIFICATION - EXPERIMENTAL CHARACTERIZATION

Immunoaffinity adsorption is increasingly used far protein purificatio n and medical applications. Synthetic membranes have advantages as sup port matrices in comparison to conventional bead supports because they are not compressible and they eliminate internal diffusion limitation s. The goal of this study was to explore in detail the performance of microporous hollow fibers composed of modified polysulfone to which pr otein A was immobilized for adsorption of human IgG. The internal matr ix was characterized by scanning electron microscopy. The binding equi librium constant was measured using both static and dynamic methods. B reakthrough curves up to ligand saturation were measured and used to s tudy the effects of IgG concentration, presence of contaminant albumin , flow direction, flow mode, and especially filtrate flow rate and max imum IgG binding capacity. The highest binding capacities studied were comparable with that attainable with bead matrices. All of the breakt hrough curves could be represented on a single figure when plotted ver sus the dimensionless relative throughput (the mass of IgG loaded on t he membrane divided by the mass that would be bound when the entire fi ber is in equilibrium with the feed concentration), and the effect of operating variables on the position and shape of the individual breakt hrough curves,could be understood in terms of a dimensional performanc e parameter (the product of membrane volume and maximum binding capaci ty divided by the filtrate flow rate). The best breakthrough curves we re obtained with the highest values of the performance parameter. Base d on the results, membranes as solid supports for immunoadsorption can be a useful alternative to the use of traditional columns for protein separations. (C) 1995 John Wiley & Sons, Inc.