Abstract
In this study, the effect of grafted dextran on the pore size of anion-exchange resins was investigated to optimize the accessible surface areas and mass transfer properties of protein chromatography. Three different methacrylate polymer-based anion exchangers of BioPro (BP) with different chain lengths of dextran (BP-0-Q, BP-60-Q, and BP-200-Q) were prepared. The mean pore radii of BP-0-Q, BP-60-Q, and BP-200-Q were 24.0, 10.6, and 6.2 nm, respectively, indicating that the penetration of proteins inside the pore was different depending on the chain length of the grafted dextran. Furthermore, the accessibility of human IgG antibodies to the surface inside the pore was the highest for BP-60-Q, suggesting that the dextran polymer of 60 kDa grafted on the pore maximized the accessible surface area of the resin. The static binding capacity of human IgG on BP-60-Q was 78 mg/cm3, which was 73% of the capacity of BP-200 Q and comparable to that of the conventional resins tested. According to the results of linear gradient elution experiments using human IgG, the values of the reduced height equivalent to a theoretical plate (h) of BP-60-Q were smaller than those of BP-200-Q as well as the conventional resins tested. The results indicate that BP-60-Q exhibited the highest performance for the chromatographic purification of human IgG with balanced binding capacity and mass transfer properties among the resins tested. Therefore, by changing the chain length of the grafted dextran, the pore radii of the resins were controlled, and thus, the binding capacity and mass transfer of the resin were optimized according to the target protein size.
