Improvement of protein binding capacity of acrylic-acid-grafted fibers by polymer root-to-brush shift

A weak acid cation exchange fiber used for large-scale antibody purification was prepared by radiation-induced graft polymerization of acrylic acid (AA) onto a commercially available nylon-6 fiber. The AA-grafted fiber was post-treated by conditioning in NaOH aqueous solution at 298 K followed by immersion in water at 353 K to increase the protein binding capacity of the cation exchange fiber. A 2 g/L lysozyme solution buffered at pH 6.0 flowed through a column charged with a treated or untreated AA-grafted fiber at a space velocity of 20 h−1. The 10% dynamic binding capacity of the column charged with the former fiber of 200 mg/mL-column was 5.9-fold that of the column charged with the latter fiber, and 2.3-fold that (88 mg/mL-column) of a column charged with CM Sepharose™ Fast Flow (GE Healthcare). •Acrylic-acid-grafted fibers were post-treated by immersion in water at 353 K.•Binding capacities of the fibers for lysozyme were evaluated in a flow-through mode.•Dynamic binding capacity (DBC) of the fiber for lysozyme reached 200 mg/mL-bed.•The DBC of the post-treated fiber was 5.9-fold that of the untreated fiber.