Nd–Fe–B alloy-densified agarose gel for expanded bed adsorption of proteins

Novel dense composite adsorbents for expanded bed adsorption of protein have been fabricated by coating 4% agarose gel onto Nd–Fe–B alloy powder by a water-in-oil emulsification method. Two composite matrices, namely Nd–Fe–B alloy-densified agarose (NFBA) gels with different size distributions and densities, NFBA-S (50–165 μm, 1.88 g/ml) and NFBA-L (140–300 μm, 2.04 g/ml), were produced. Lysozyme was used as a model protein to test the adsorption capacity and kinetics for the NFBA gels modified by Cibacron blue 3GA (CB-NFBA gels). Liquid-phase dispersion behavior in the expanded beds was examined by measurements of residence time distributions, and compared with that of Streamline SP (Amersham–Pharmacia Biotech, Sweden). The dependence of axial mixing in the expanded beds on flow velocity, bed expansion degree, settled bed height, and viscosity of liquid phase was investigated. Breakthrough curves of lysozyme in the expanded beds of the CB-NFBA gels were also examined. The dynamic binding capacity at 5% breakthrough was 23.3 mg/ml matrix for the CB-NFBA-S gels, and 16.7 mg/ml matrix for the CB-NFBA-L, at a flow velocity of 220 cm/h. The results indicate that the NFBA gels are promising for expanded bed adsorption of proteins.