Fabrication and characterization of macroporous epichlorohydrin cross-linked alginate beads as protein adsorbent

Porous epichlorohydrin cross-linked alginate beads (ECAB) were prepared by the following method. Na-alginate solution containing Na2SO4 was introduced dropwise into CaCl2 solution to simultaneously form CaSO4 precipitate and Ca-alginate gel beads. The resultant beads were cross-linked with epichlorohydrin and then thoroughly washed with ethylenediamine tetraacetic acid (EDTA) solution to remove CaSO4. The structural features of porous ECAB were assessed with scanning electron microscopy (SEM) and experiments on water content and adsorption of bovine serum albumin (BSA). The results showed that macroporous ECAB can be obtained when the mass ratio of sodium sulfate to sodium alginate is 4:1. The adsorption behavior of the macroporous ECAB was well described by the Langmuir isotherm with maximum adsorption capacity equal to 740 mg BSA/g dry weight in 50 mM Na2HPO4-citric acid buffer (pH 4.0). BSA was more effectively adsorbed by macroporous ECAB at around pH 3 and the mechanism of the adsorption of BSA to the ECAB was ion exchange. Finally, experiments of a concentration of 1 mg/mL BSA using macroporous ECAB were performed.