Grafting diethylaminoethyl dextran to macroporous cellulose microspheres: A protein anion exchanger of high capacity and fast uptake rate

Abstract

Ion exchangers with high adsorption capacity and fast mass transfer synchronously are highly desired for protein separation and purification. For this purpose, here, we develop a high-performance anion exchanger by grafting diethylaminoethyl dextran (DEAE-dextran) on macroporous cellulose microspheres (MCMs). Static adsorption experiments for bovine serum albumin (BSA) show that the DEAE-dextran grafted MCMs have a higher adsorption capacity of 192.6 mg/mL than traditional non-grafted DEAE modified anion exchangers at a similar ionic capacity. The high adsorption capacity is due to the three-dimensionally extended polymer chains in pores that provide more and easily accessible ligands. Uptake kinetic results reveal that the DEAE-dextran grafted MCMs have a fast mass transfer rate and the maximum ratio (De/D0) of effective pore diffusivity (De) to free solution diffusivity (D0) reach 0.96, which is over three times higher than traditional non-grafted DEAE modified MCMs (0.29) and over nine times higher than commercial DEAE Sepharose FF (<0.10). It is attributed to the synergistic effect of the macropores and grafting ligands. The macropores provide wide channels for intraparticle pore diffusion, and the grafting ligands facilitate the surface transport of BSA by chain delivery occurred between adjacent DEAE-dextran chains. All these results demonstrate the DEAE-dextran grafted MCMs are promising as high-performance ion exchangers.