DNA nanotechnology in the undergraduate laboratory: Analysis of molecular topology using DNA nanoswitches

There is a disconnect between the cutting-edge research done in academic labs, such as nanotechnology, and what is taught in undergraduate labs. In the current undergraduate curriculum, very few students get a chance to do hands-on experiments in nanotechnology-related experiments most of which are through selective undergraduate research programs. In most cases, complicated synthesis procedures, expensive reagents, and requirement of specific instrumentation prevent broad adaptation of nanotechnology-based experiments to laboratory courses. DNA, being a nanoscale molecule, has recently been used in bottom-up nanotechnology with applications in sensing, nano-robotics, and computing. In this article, we propose a simple experiment involving the synthesis of a DNA nanoswitch that can change its shape from a linear "off" state to a looped "on" state in the presence of a target DNA molecule. The experiment also demonstrates the programmable topology of the looped state of the nanoswitch and its effect on gel migration. The experiment is easy to adapt in an undergraduate laboratory, requires only agarose gel electrophoresis, a minimal set-up cost for materials, and can be completed in a 3-hour time frame.