Electro-/Magnetophoretic Partitioning in Two-Phase Microflows

One of the most important steps in Lab-on-a-Chip systems concerns the purification and fractionation of biological samples containing constituents such as cells or proteins. Sample fractionation is done by exploiting different physico-chemical properties of the constituents such as the electrophoretic mobility or hydrophobicity. In a current project we aim at extending the space of separation criteria by considering the transport of species across a phase boundary between two immiscible liquids. By exploiting the interaction of biomolecules or small particles with such interfaces it could become possible to establish new protocols for sample fractionation and purification.

When DNA molecules or micro-/nanoparticles are electro-/magnetophoretically transported to the liquid-liquid interface in an aqueous two-phase system, they usually get attached to the interface. Upon increasing the force driving the molecules/particles, a detachment from the interface is observed. The detachment process is specific for certain properties of the molecules/particles such as their size. That way a species separation which relies on a different mechanism compared to conventional schemes such as capillary electrophoresis can be achieved.

Publications

T. Hahn and S. Hardt, Concentration and size-separation of DNA samples at liquid-liquid interfaces, Anal. Chem. 83 (2011), 5476–5479.

T. Hahn and S. Hardt, Size-dependent detachment of DNA molecules from liquid-liquid interfaces, Soft Matter 7 (2011), 6320–6326.

T. Hahn, G. Münchow and S. Hardt, Electrophoretic transport of biomolecules across liquid-liquid interfaces, J. Phys. – Condens. Mat. 23 (2011), 184107.