Berlin 2008 – scientific programme

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BP: Fachverband Biologische Physik

BP 2: DNA and Chromatin

BP 2.7: Talk

Monday, February 25, 2008, 12:15–12:30, PC 203

Conformational DNA separation by dielectrophoresis — •Jan Regtmeier¹, Ralf Eichhorn², Alexandra Ros¹, and Dario Anselmetti¹ — ¹Experimental Biophysics & Applied Nanoscience, Bielefeld University, Universitaetsstr. 25, 33615 Bielefeld, Germany — ²Condensed Matter Theory, Bielefeld University, Universitaetsstr. 25, 33615 Bielefeld, Germany

In modern biotechnology and pharmaceutics applications, topologically closed circular DNA plays an important role. For instance, plasmids are used as genetic vectors in DNA recombinants, and for in vivo gene therapy. The latter makes high purification and exact characterization of plasmid DNA indispensable.

We extend our previous studies [1] and present the separation of DNA fragments with equal number of base pairs according to their conformation (supercoiled from linear DNA fragments). The separation is performed in a microfluidic poly(dimethylsiloxane) (PDMS) chip within 210 s. The device consists of a cross injector and a microstructured separation channel with a periodic array of nonconducting posts. The application of an AC voltage induces dipoles in the DNA molecules, which couple to the inhomogeneous electric field in the post array (dielectrophoretic trapping). Superimposed application of a DC voltage induces DNA migration and separation, based on differences in DNA polarizabilities. A detailed analysis of the trapping times allows quantification of the DNA polarizabilities.

[1] Dielectrophoretic Manipulation of DNA: Separation and Polarizability, J. Regtmeier et al., Anal. Chem. 79, 3925-3932 (2007)