Recent developments in the analysis and the application of DNA often require the stretching of individual DNA molecules to specific surfaces. We propose and demonstrate a method for the positioning of unmodified extended DNA molecules. A local microscopic circular flow is created by a non-uniform AC field and utilized to stretch the lambda-DNA on a gold surface or between gold electrodes. The electrical-field amplitude and frequency responses of DNA motion are studied. The method can be applied to position the DNA with accuracy on a microscopic scale while requiring no modification of the DNA for terminal binding. With a diluted DNA solution, the number of DNA molecules across the electrodes is controllable and the positioning of a single extended DNA across electrodes is achievable.
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