Dense pellicular agarose-glass beads for expanded bed application: Fabrication and characterization for effective protein adsorption

Dense pellicular composite solid matrices had been prepared by coating 4% agarose gel onto glass beads by a water-in-oil emulsification method. Two pellicular matrices, namely agarose-coated small glass bead (AG-S, 70-190 mum, mean size 120 mum) and agarose-coated large glass beads (AG-L, 130-280 mum, mean size 200 mum), were fabricated. The densities of AG-S and AG-L were as high as 1.77 and 1.98 g/ml, and the average depth of the agarose pellicle was estimated to be 20-30 mum, respectively. The matrices were modified with Cibacron Blue 3GA (CB) and lysozyme adsorption equilibrium and kinetic properties of the dye-ligand adsorbents were evaluated with the Langmuir equation and pore diffusion model, respectively. Stability of the matrices in basic solution and in recycled use was confirmed. It is found that the apparent pore diffusion coefficient of lysozyme in the pellicular beads was over two times higher than that in a homogeneous matrix due to their pellicular assembly. At nearly same the liquid velocity, the expanded bed of AG-S had approximately twofold higher plate number than that of AG-L, so the expanded bed of the former was much more efficient than that of the latter. Moreover, due to the rapid mass transfer property of the pellicular adsorbent CB-AG-S, its expanded bed showed a dynamic capacity over twice that of a commercial homogeneous medium designed for expanded bed application. (C) 2003 Elsevier B.V. All rights reserved.