Petropoulos J H, Liapis A I, Kolliopoulos N P, Petrou J K, Kanellopoulos N K
Physical Chemistry Institute, National Research Center for Physical Sciences DEMOKRITOS, Athens, Greece.
Bioseparation. 1990;1(1):69-88.
A restricted diffusion model is constructed and solved in order to study the permeability of large adsorbate molecules in the pores of affinity chromatography media, when the adsorbate molecules are adsorbed onto immobilized ligands. The combined effects of steric hindrance at the entrance to the pores and frictional resistance within the pores, as well as the effects of pore size distribution, pore connectivity of the adsorbent, molecular size of adsorbate and ligand, and the fractional saturation of adsorption sites (ligands), are considered. Affinity adsorbents with dilute and high ligand concentrations are examined, and the permeability of the adsorbate in porous networks of connectivity nT is studied by means of effective medium approximation (EMA) numerical solutions. As expected, the permeability of the adsorbate decreases as the size of the adsorbate and/or ligand molecule increases. The permeability also decreases when the fractional saturation of the ligands increases, as well as when the pore connectivity of the network decreases. The dependence of the permeability on the pore connectivity tends to be less marked in adsorbents with concentrated ligand than in porous media with dilute ligand concentration. The conditions are also presented for which the percolation threshold is attained in a number of different systems. The restricted diffusion model and results of this work may be of importance in studies involving the modeling, prediction of the dynamic behavior, design, and control of affinity chromatography (biospecific adsorption) systems employing porous adsorbents. The theoretical results may also have important implications in the selection of a ligand as well as in the selection and construction of an affinity porous matrix, so that the adsorbate of interest can be efficiently separated from a given solution. Furthermore, with appropriate modifications this restricted diffusion model may be used in studies involving the immobilization of ligands or enzymes in porous solids.
为了研究大吸附质分子在亲和色谱介质孔中的渗透性，构建并求解了一个受限扩散模型，此时吸附质分子被吸附到固定化配体上。考虑了孔入口处的空间位阻和孔内的摩擦阻力的综合影响，以及孔径分布、吸附剂的孔连通性、吸附质和配体的分子大小以及吸附位点（配体）的分数饱和度的影响。研究了配体浓度低和高的亲和吸附剂，并通过有效介质近似（EMA）数值解研究了吸附质在连通性为nT的多孔网络中的渗透性。正如预期的那样，吸附质的渗透性随着吸附质和/或配体分子大小的增加而降低。当配体的分数饱和度增加时，以及当网络的孔连通性降低时，渗透性也会降低。与配体浓度低的多孔介质相比，配体浓度高的吸附剂中渗透性对孔连通性的依赖性往往不太明显。还给出了在许多不同系统中达到渗流阈值的条件。这项工作的受限扩散模型和结果可能对涉及使用多孔吸附剂的亲和色谱（生物特异性吸附）系统的建模、动态行为预测、设计和控制的研究具有重要意义。理论结果在配体的选择以及亲和多孔基质的选择和构建方面也可能具有重要意义，以便能够从给定溶液中有效分离出感兴趣的吸附质。此外，经过适当修改，这个受限扩散模型可用于涉及在多孔固体中固定配体或酶的研究。
