Advances in Resins for Ion-Exchange Chromatography

Protein adsorption and transport in polymer-functionalized ion-exchangers

“…Complementary data showing similar trends are seen in comparisons of protein adsorption on different media measured using high-throughput screening methods [10]. These measurements were acquired via batch measurements that did not necessarily attain equilibrium, with the measured values reported as “binding capacity strength”.…”

“…The most comprehensive set of data is from a large set of studies involving five proteins and a wide variety of strong and weak cation and anion exchangers [38–43], augmented by additional results in a recent review [10]; these studies reported practical functional measures of performance such as dynamic capacities as well as more basic measures of retention and transport efficiency, such as plate heights. Although polymer-derivatized media represented only a fraction of the adsorbents studied, the trends were sometimes clear enough for the distinctive properties of this class of media to be identifiable.…”

“…Full isotherms have been reported for several proteins of different sizes on different types of polymer-functionalized media, including dextran-containing Sepharose XL and Capto adsorbents [10,23,56] and custom-synthesized analogs [26,47], GigaCap materials [10,49] and HyperD gel-in-a-shell products [10,37,60]. Although lysozyme has been by far the most frequently used protein for such studies, there is sufficient breadth, reproducibility and variety to conclude that, despite the appreciable differences among these materials and between them and their unmodified counterparts, the isotherms follow the same kind of concave downward form to be indistinguishable in shape from isotherms on more conventional protein chromatography media.…”

“…Similarly dramatic differences are seen in comparing the static capacities of GigaCap to that of Toyopearl SP 650, a cation exchanger without added polymer prepared on the same base matrix [49], and clear differences are also seen with Fractogel EMD media, on the same base matrix [11]. Even without a direct basis for comparison with an underivatized counterpart, the results of isotherm measurements can be informative: comparisons for multiple proteins of isotherms for a variety of ion exchangers showed HyperD and GigaCap media to have the highest plateau values [10], with the static capacity values for Sepharose XL media also consistently at the high end [10,39,42]. The high values for HyperD media presumably reflect the fully pore-filling nature of the gel, allowing essentially the full volume to be occupied by protein.…”

“…The very large data set of Staby and co-workers [10,38–43] allows many of these comparisons to be made, although comparisons among DBCs on different base matrices should be performed with some care since the “high” and “low” flow rates used for each resin were based on the maximum flow rate recommended by each manufacturer. Nevertheless, the conclusions involving polymer-functionalized media include that some of these media, such as representatives of the Sepharose XL, Ceramic HyperD and GigaCap families, tend to have among the highest absolute DBCs, at least for proteins up to about the size of BSA.…”