Dresden 2009 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 18: Polyelectrolytes

CPP 18.6: Talk

Tuesday, March 24, 2009, 10:45–11:00, ZEU 114

Self-stretching of DNA-amphiphile complexes on pre-coated graphite surfaces — •Hua Liang, Wei Zhuang, Nikolai Severin, and Jürgen P. Rabe — Department of Physics, Humboldt University Berlin, Newtonstr.15, D-12489 Berlin, Germany

Stretching single DNA molecules on a surface is important, for instance for the purpose of direct DNA sequencing with scanning probe techniques and for studies of enzyme activities [1]. Micrometer-long single DNA molecules have been deposited and aligned on a poly-L-lysine modified mica surface [2]. However this method does not allow to stretch the molecules perfectly, which makes sequencing a difficult task. Here we report a method which allows us to stretch both single- and double-stranded DNA (ss-, ds-DNA) and even overstretch ds-DNA on an amphiphile pre-coated graphite surface. DNA-amphiphile complexes form during adsorption of DNA molecules on the amphiphile pre-coated surface. The complex self-stretches on the HOPG surface. Annealing at 60 °C stretches ds-DNA furthermore up to 1.42 times its original B-form length. ss-DNA can be stretched up to 0.45 nm/base, compared to 0.39 nm/base on poly-L-lysine pre-coated mica [2]. A mechanism for self-stretching is also suggested.

[1] X. Michalet, Nano Letters 1 (2001) 341-343 [2] A. T. Woolley, R. T. Kelly, Nano Letters 1 (2001) 345-348