【Original Contribution】 Reduction of Buffer Volume Used in Regeneration ofAnion–Exchange Porous Hollow–Fiber Membrane by Site–ControlledIntroduction of Anion–Exchange Group into Graft Chain

Abstract

A porous hollow–fiber membrane containing an anion–exchange graft chain is used as an adsorber for the removalof undesirable proteins. The adsorption and elution of the proteins are followed by the regeneration of the mem-brane. The volume of a buffer solution used for the regeneration of the anion–exchange porous hollow–fiber mem-brane was reduced by controlling the anion–exchange group distribution along the graft chain. First, glycidylmethacrylate(GMA)was graft-polymerized onto an electron–beam–irradiated porous hollow–fiber membrane.Second, diethylamino group was introduced into the epoxy group of the graft chain with water as a poor solvent forthe poly GMA chain. In a permeation mode, the membrane was regenerated with 1.0 M sodium hydroxide beforebeing rinsed with a phosphate buffer (pH 7.0). When the anion–exchange group was introduced preferentially intothe polymer brush, the buffer solution usage required to rinse the membrane to pH 7.2 was reduced by 40% com-pared to when the anion–exchange group was introduced uniformly along the graft chain. The binding capacity ofBSA to the polymer brush remained constant irrespective of the anion-exchange group distribution along the graft chain.