Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, P R China.
J Sep Sci. 2011 Nov;34(21):2950-9. doi: 10.1002/jssc.201100394. Epub 2011 Sep 23.
In the current research, a series of dextran-grafted adsorbents were prepared using sulfopropyl and 4-(1H-imidazol-1-yl) aniline as chromatographic ligands for ion-exchange (IEC) and mixed-mode chromatography (MMC) to respectively investigate the influence of dextran layer on adsorption of γ-globulin. Experimental evidences of static adsorption on dextran-grafted IEC adsorbents showed that adsorption capacity of γ-globulin increased with dextran content. It could be attributed to the multilayer adsorption of charged protein in dextran layer and thus further induced a significant electrical potential gradient at the boundary of adsorbed area and its proximity, improving mass transfer in combination with concentration gradient. In contrast to IEC adsorbents, adsorption capacity and effective diffusivity of dextran-grafted MMC adsorbents did not change obviously with dextran grafting. It was considered that hydrophobic ligands immobilized onto dextran-grafted MMC adsorbents were stuck together at pH 8.0, resulting in the collapse of dextran layer. In concert with measured effective porosity for γ-globulin at pH 4.0, it was confirmed that dextran layer in MMC adsorbent was more complicated and influenced significantly by buffer pH. It was also manifested by protein adsorption at different pHs. Thus, it revealed the complexity in intraparticle mass transfer of the protein in dextran-grafted MMC adsorbent.
在当前的研究中，使用磺丙基和 4-(1H-咪唑-1-基)苯胺作为色谱配体，制备了一系列葡聚糖接枝吸附剂，用于离子交换（IEC）和混合模式色谱（MMC），分别研究葡聚糖层对γ-球蛋白吸附的影响。葡聚糖接枝 IEC 吸附剂的静态吸附实验证据表明，γ-球蛋白的吸附容量随葡聚糖含量的增加而增加。这可以归因于带电荷的蛋白质在葡聚糖层中的多层吸附，从而在吸附区域及其附近边界进一步诱导显著的电势梯度，结合浓度梯度改善传质。与 IEC 吸附剂相比，葡聚糖接枝 MMC 吸附剂的吸附容量和有效扩散系数并没有随葡聚糖接枝而明显变化。据认为，在 pH 8.0 时，固定在葡聚糖接枝 MMC 吸附剂上的疏水性配体粘在一起，导致葡聚糖层坍塌。与在 pH 4.0 下测量的γ-球蛋白的有效孔隙率一致，证实了 MMC 吸附剂中的葡聚糖层更复杂，受缓冲液 pH 值的影响显著。这也表现在不同 pH 值下的蛋白质吸附上。因此，它揭示了葡聚糖接枝 MMC 吸附剂中蛋白质的颗粒内传质的复杂性。
