Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 24: Micro and Nano Fluidics II: Soft Objects in Flow + Slippage

CPP 24.2: Talk

Thursday, March 29, 2007, 10:00–10:15, H37

Spontaneous stretching of DNA in a two-dimensional nanoslit — •Madhavi Krishnan and Petra Schwille — Institut für Biophysik, Biotechnologisches Zentrum der TU Dresden, 01307 Dresden, Germany

We report a novel regime of polyelectrolyte behaviour manifested in the stretching of DNA molecules confined in solution to two dimensions that arises from the combined effects of confinement and electrostatics in nanoslits. We observe that a proportion of DNA molecules in slit-shaped silicon dioxide-glass channels, a few microns wide and 50 to 100 nm deep, spontaneously assumes axially extended configurations at the lateral sidewalls of the slit, exhibiting thermal fluctuations in contour length predominantly along the major axis of the slit. The situation resembles that of extension of a physically confined polymer chain in a nanochannel, with the important exception that the nanochannel confines the DNA molecule in two of three spatial dimensions, while the nanoslit involves actual physical confinement in only one spatial dimension; confinement in the second spatial dimension is gratuitous, and appears to be electrostatically mediated. The spontaneous ordering and extension of DNA molecules in fluidic slits with depths comparable to persistence length of DNA, is not only of fundamental relevance in understanding electrostatic interactions between confined charged entities but also offers a novel, greatly simplified method to stretch DNA in solution for DNA-protein interaction studies.