Tao Yinying, Carta Giorgio
Department of Chemical Engineering, University of Virginia, 102 Engineers' Way, Charlottesville, VA 22904-4741 USA.
J Chromatogr A. 2008 Nov 21;1211(1-2):70-9. doi: 10.1016/j.chroma.2008.09.096. Epub 2008 Oct 4.
The binding capacity and adsorption kinetics of a monoclonal antibody (mAb) are measured for experimental cation exchangers obtained by grafting dextran polymers to agarose beads and compared with measurements for two commercial agarose-based cation exchangers with and without dextran grafts. Introduction of charged dextran polymers results in enhanced adsorption kinetics despite a dramatic reduction of the accessible pore size as determined by inverse size-exclusion chromatography. Incorporation of neutral dextran polymers in a charged agarose bead results instead in substantially lower binding capacities. The effective pore diffusivities obtained from batch uptake curves increase substantially as the protein concentration is reduced for the resins containing charged dextran grafts, but are much less dependent on protein concentration for the resins with no dextran or uncharged dextran grafts. The batch uptake results are corroborated by microscopic observations of transient adsorption in individual particles. In all cases studied, the adsorption kinetics is characterized by a sharp adsorption front consistent with a shell-progressive, diffusion limited mechanism. Greatly enhanced transport rates are obtained with an experimental resin containing charged dextran grafts with effective pore diffusivities that are 1-9 times larger than the free solution diffusivity and adsorption capacity approaching 300 mg/cm3 of particle volume.
对通过将葡聚糖聚合物接枝到琼脂糖珠上获得的实验性阳离子交换剂，测量了单克隆抗体（mAb）的结合能力和吸附动力学，并与两种有或没有葡聚糖接枝的商业琼脂糖基阳离子交换剂的测量结果进行了比较。尽管通过反相尺寸排阻色谱法测定的可及孔径显著减小，但引入带电荷的葡聚糖聚合物会导致吸附动力学增强。相反，在带电荷的琼脂糖珠中加入中性葡聚糖聚合物会导致结合能力大幅降低。对于含有带电荷葡聚糖接枝的树脂，从分批摄取曲线获得的有效孔扩散率随着蛋白质浓度的降低而大幅增加，但对于没有葡聚糖或不带电荷葡聚糖接枝的树脂，其对蛋白质浓度的依赖性要小得多。分批摄取结果通过对单个颗粒中瞬时吸附的显微镜观察得到了证实。在所研究的所有情况下，吸附动力学的特征是有一个尖锐的吸附前沿，这与壳层渐进、扩散受限机制一致。使用含有带电荷葡聚糖接枝的实验树脂可获得大大提高的传输速率，其有效孔扩散率比自由溶液扩散率大1至9倍，吸附容量接近300 mg/cm³颗粒体积。
