Center of Smart Interfaces, TU Darmstadt, Darmstadt, Germany.
J Phys Condens Matter. 2011 May 11;23(18):184107. doi: 10.1088/0953-8984/23/18/184107. Epub 2011 Apr 20.
The mass transfer resistance of a liquid-liquid interface in an aqueous two-phase system composed of poly(ethylene glycol) and dextran is investigated. Different types of proteins and DNA stained with fluorescent dyes serve as probes to study the transport processes close to the interface. A microfluidic device is employed to enable the electrophoretic transport of biomolecules from one phase to another. The results obtained for proteins can be explained solely via the different electrophoretic mobilities and different affinities of the molecules to the two phases, without any indications of a significant mass transfer resistance of the liquid-liquid interface. By contrast, DNA molecules adsorb to the interface and only desorb under an increased electric field strength. The desorption process carries the signature of a thermally activated escape from a metastable state, as reflected in the exponential decay of the fluorescence intensity at the interface as a function of time.
本文研究了聚乙二醇和葡聚糖组成的双水相体系中液-液界面的传质阻力。不同类型的蛋白质和用荧光染料染色的 DNA 被用作探针，以研究接近界面的传输过程。采用微流控装置实现了生物分子从一相向另一相的电泳传输。对于蛋白质的结果可以仅通过分子的不同电泳迁移率和对两相的不同亲和力来解释，而没有任何迹象表明液-液界面存在显著的传质阻力。相比之下，DNA 分子会吸附到界面上，只有在增加电场强度的情况下才会解吸。解吸过程表现出从亚稳态热激活逃逸的特征，这反映在界面处的荧光强度随时间的指数衰减中。
