Trilisky Egor I, Lenhoff Abraham M
Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, USA.
Biotechnol Bioeng. 2009 Sep 1;104(1):127-33. doi: 10.1002/bit.22370.
The need for purification of biomolecules extends to larger bioparticles as well. For example, virus purification is required for production of many vaccines and gene delivery vectors, and understanding virus removal in porous media is also important in downstream processing of therapeutic proteins and in purification of water in soils. A convective entrapment mechanism for retention of large bioparticles is discussed here based on retention of such bioparticles in pore constrictions at high enough flow rates, even under non-binding conditions. A simple equation to predict whether such entrapment is expected to occur in a given system is derived based on a Péclet number that is proportional to the flow rate and to the cube of the bioparticle diameter. To test the theory, adenovirus was spiked onto chromatographic beds. As expected from the theory, under non-interacting conditions a progressively larger amount of virus becomes trapped with increasing flow rate. The entrapment is reversible upon flow rate reduction, which, within the proposed model, is based on the possibility of diffusive escape from pore constrictions. This mechanism can be exploited for virus purification or removal, and the theory is also consistent with the anecdotal evidence that monoliths and membranes are more difficult to clean than conventional chromatographic beds, especially at high flow rates.
对生物分子进行纯化的需求也延伸到了更大的生物颗粒。例如，许多疫苗和基因递送载体的生产都需要进行病毒纯化，而且了解病毒在多孔介质中的去除情况对于治疗性蛋白质的下游加工以及土壤中的水净化也很重要。本文讨论了一种基于大生物颗粒在足够高流速下于孔隙收缩处的保留情况（即使在非结合条件下）的对流截留机制，用于保留大生物颗粒。基于与流速和生物颗粒直径的立方成正比的佩克莱数，推导出了一个简单的方程，用于预测在给定系统中是否会发生这种截留。为了验证该理论，将腺病毒添加到色谱柱上。正如该理论所预期的那样，在非相互作用条件下，随着流速增加，越来越多的病毒被截留。当流速降低时，截留是可逆的，在所提出的模型中，这是基于从孔隙收缩处扩散逃逸的可能性。这种机制可用于病毒纯化或去除，而且该理论也与整体柱和膜比传统色谱柱更难清洗这一传闻证据相符，尤其是在高流速下。
