Protein adsorption to diethylaminoethyl-dextran grafted macroporous cellulose microspheres: A critical pore size for enhanced adsorption capacity and uptake kinetic

Abstract

To study the details of the effect of pore size on the performance of grafting-ligand ion exchangers, four diethylaminoethyl-dextran grafted macroporous cellulose microspheres with different pore sizes ranging from 164.57 to 281.96 nm were selected to investigate their adsorption equilibria and kinetics for bovine serum albumin (BSA) and γ-globulin. It was found that for whether adsorption equilibria or uptake kinetics, both the proteins showed increasing-then-decreasing trends with the decreasing pore size. More importantly, for a specific protein, the maximum adsorption capacity and fastest uptake rate were achieved on the same media, indicating the existence of a critical pore size (CPZ), at which the adsorption capacity and uptake kinetic are significantly enhanced synchronously. The CPZs of BSA and γ-globulin were identified to be 216.64 and 266.93 nm, respectively. Experimental results and analyses revealed that the high adsorption capacities at CPZ are attributed to the high utilization of binding sites in pores, and the uptake kinetics are enhanced by the combination of fast pore diffusion and chain delivery effect.