Bioseparations via Coupled TPP and Electrostatic Forces

摘要膜法在生物制品的下游提纯中具有广阔的应用前景。然而，目前的设备受到缺乏选择性和与蛋白质污染相关的问题的限制。这项工作的目标是研究一种增强型膜分离技术的发展，该技术结合使用界面电相互作用来提高整体选择性，并通过跨膜压力脉冲（TPP）来减少膜污染并增加通量。最初的实验研究是使用定义明确的蛋白质溶液，其中含有一种或两种蛋白质和具有良好表征性质的标准超滤膜。将进行批细胞和横流超滤（UF）实验，以评估模型单组分溶液和含TPP和不含TPP的蛋白质二元混合物的转运。在一系列缓冲条件下获得的数据表明，使用具有不同表面电荷特性的膜在分离中利用静电相互作用的有效性。通过毛细管电泳测定蛋白质电荷，通过测量流动电位分析每次运行前后的膜电荷。术后溶液分析和膜水力渗透性数据用于定量确定膜污染程度作为操作条件、膜表面特征和蛋白质特性的函数。数据分析采用因子设计和方差分析（ANOVA）来识别改善溶质筛分、溶质通量和整体净化因子的最重要因素。这些实验研究得到了体积和膜传输现象的理论分析的补充，包括静电相互作用和跨膜压力脉冲的影响。动态TPP与适当利用静电相互作用的结合有可能显著提高蛋白质分离膜的性能。特别是，利用电相互作用来排斥选择性带同种电荷的物质，可以用市售的膜材料实现非常高分辨率的分离。跨膜压力脉冲将允许这些设备以更高的吞吐量运行，同时最大限度地减少膜污染。最终的结果是，这项技术应该能够显著提高膜系统的总体产量、纯化系数和吞吐量特性，使这些设备能够用于生物技术和生物医学行业的全新应用范围。例如，由于膜工艺本身具有成本效益，并且对脆弱的生物成分几乎没有损害，因此这项技术的成功实施可以使从牛奶和血浆等天然来源生产新的治疗性蛋白质和营养品的工艺成为可能，也可以开发用于从血浆中去除自身抗体的新型生物医学设备，或者用基于动态传质的人工器官治疗危及生命的疾病。

CTS-0091552Bioseparations using Coupled TPP and Electrostatic ForcesVictor G.J. Rodgers (University of Iowa) Andrew L. Zydney (University of Delaware)AbstractMembrane processes have great potential for use in the downstream purification of a wide range of biological products. However, current devices are limited by a lack of selectivity and problems associated with protein fouling. The goal of this work is to examine the development of an enhanced membrane separation technology that combines the use of interfacial electrical interactions to enhance the overall selectivity with transmembrane pressure pulsing (TPP) to reduce membrane fouling and increase flux. Initial experimental studies are using well-defined protein solutions containing either one or two proteins and standard ultrafiltration membranes with well characterized properties. Batch-cell and crossflow ultrafiltration (UF) experiments will be performed to evaluate the transport of model single-component solutions and binary mixtures of proteins with and without TPP. Data obtained over a range of buffer conditions indicate the efficacy of using membranes with different surface-charge characteristics to exploit electrostatic interactions on the separation. Protein charge is determined by capillary electrophoresis, and the membrane charge is analyzed both before and after each run by measuring the streaming potential. Post-operative solution analysis and membrane hydraulic permeability data are used to determine quantitatively the extent of membrane fouling as a function of operating conditions, membrane surface characteristics, and protein properties. The data analysis employs factorial design and analysis of variance (ANOVA) to discern the most significant factors in improving solute sieving, solute flux, and overall purification factor. These experimental studies are complimented by theoretical analyses of bulk and membrane transport phenomena, including the effects of both the electrostatic interactions and the transmembrane pressure pulsing.The combination of dynamic TPP with the proper exploitation of electrostatic interactions has the potential to provide significant enhancements in protein-separation membrane performance. In particular, the use of electrical interactions to repel selectively like-charged species should enable very high resolution separations to be accomplished with commercially available membrane materials. Transmembrane pressure pulsing will allow these devices to be operated at much higher throughput while minimizing membrane fouling. The net result is that this technology should be able to improve dramatically the overall yield, purification factor, and throughput characteristics of membrane systems, allowing these devices to be used for an entirely new range of applications in the biotechnology and biomedical industries. For example, because membrane processes are inherently cost effective and cause little damage to fragile biological components, successful implementation of this technology could enable processes for the production of new therapeutic proteins and nutraceuticals from natural sources like milk and plasma, the development of new biomedical devices for removal of auto-antibodies from plasma, or the treatment of life-threatening diseases with dynamic mass-transfer-based artificial organs.