Protein Binding Characteristics of Amphoteric Polymer Brushes Grafted onto Porous Hollow-Fiber Membrane

Abstract

Three types of ampholites containing dimethylamino and carboxyl groups, i. e., N (CH3) 2 (CH2) nCOOH (n=1-3), were introduced into an epoxy-group-containing polymer brush grafted onto a porous hollow-fiber membrane with a porosity of 70% and pore size of 0.36 μm. Lysozyme was captured by the amphoteric polymer brush during the permeation of a lysozyme solution buffered with a carbonate buffer (pH 9.0) across the ampholite-immobilized porous hollow-fiber membranes. The N (CH3) 2 (CH2) 2 COOH-immobilized porous membrane exhibited a fivefold higher flux for the buffer solution and a 50-fold lower binding capacity for lysozyme at a lower molar conversion of the epoxy group into the amphoteric group, up to 17%, than the other two types of membranes.