4 December 2003 Electrophoretic migration of DNA in lyotropic liquid crystals
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Lyotripic liquid crystals form highly regular porous matrices with aqueous channels on the nanometer length scale. We have used the cubic phases formed with water by either an amphiphilc block-copolymer (Pluronic F127) or by a lipid (monoolein) for electrophoretic separation of DNA and other biomolecules. Our goal is to use the well-defined pores and the amphiphilic environment to obtain new separation motifs compared to conventional matrices, and to exploit the well-known phase diagrams of these two systems to optimise applications. The Pluronic crystal consists of close-packed micelles and its main advantage is that the cubic phase melts below 10°C, and we show that the separated DNA can be recovered in a biologically active state in preparative applications. Our mechanistic studies revealed that double-stranded DNA undergoes a highly non-conventional (non-reptative) mode of migration, with the helix axis perpendicular to the field direction because the DNA migrates in the grain boundaries of the polycrystalline samples. In contrast to the Pluronic case, the monoolein cubic crystal is bicontinuous, and a main advantage is that it is in equilibrium with a water-rich phase. We exploited this phase-behaviour in the useful sub-marine mode of analytical electrophoresis. The migration of oligonucleotides in the monoolein is strongly retarded compared to free solution and conventional gels, to an extent which is consistent with that migration indeed occurs through the nm-pores. We demonstrate separation of oligonucleotides based on size, and on different types of secondary structure of the same oligonucleotide size, such as the double-stranded, single-stranded and hairpin forms.
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Bjorn Akerman, Bjorn Akerman, Roine Svingen, Roine Svingen, Nils Carlsson, Nils Carlsson, } "Electrophoretic migration of DNA in lyotropic liquid crystals", Proc. SPIE 5223, Physical Chemistry of Interfaces and Nanomaterials II, (4 December 2003); doi: 10.1117/12.513311; https://doi.org/10.1117/12.513311

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