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

Zhang, Weican, Ji, Xiaofei, Sun, Caiyun, Lu, Xuemei
Preparative biochemistry & biotechnology 2013 v.43 no.5 pp. 431-444
EDTA (chelating agent), adsorbents, adsorption, bovine serum albumin, buffers, calcium alginate, calcium chloride, calcium sulfate, crosslinking, epichlorohydrins, gels, ion exchange, pH, porous media, scanning electron microscopy, sodium alginate, sodium sulfate, sorption isotherms, water content
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.