Fabrication of superporous agarose beads for protein adsorption: Effect of CaCO3 granules content

Agarose gels were fabricated by water-in-oil emulsification with the addition of CaCO3 granules at 8–16 wt%. Thus agarose beads of different superporosities were produced after dissolving the solid porogen. The superporous agarose (SA) and homogeneous agarose gels were double cross-linked and modified with diethylaminoethyl chloride to produce anion exchangers. We have proposed to use a superporous replica (porous titania microspheres) to examine the superporous structure and pore size distribution of the soft gel. The replica was prepared with the agarose gel entrapping CaCO3 granules by a sol–gel-templating method. It was found that the superpores created by CaCO3 granules were uniformly distributed and ranged from 0.95 μm to 1.33 μm. The physical properties of the gels were significantly affected by the porogen content. Importantly, by increasing the solid porogen to 12 wt%, the bed permeability and effective porosity increased about 48% and 33%, respectively. Further increase in the porogen to 16 wt% led to a decrease of the mechanical strength. With increasing superpores in the beads, the dynamic adsorption capacity of the packed columns increased obviously at 305–916 cm/h. Besides, the column efficiency changed less with increasing flow velocity up to 1200 cm/h. It was concluded that the use of 12 wt% CaCO3 granules in agarose solution was beneficial for the fabrication of the SA gel with good mechanical stability and promising performance for protein chromatography.