Regensburg 2010 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 2: New Technologies

BP 2.5: Vortrag

Montag, 22. März 2010, 11:45–12:00, H43

A Pore-Cavity-Pore Nanodevice to Trap and Optically Investigate Single Molecules — •Martin Langecker, Daniel Pedone, and Ulrich Rant — Walter Schottky Institut, TU München

Single engineered nanopores in solid state membranes have attracted broad attention in recent years as a tool to study single biological molecules like DNA or proteins. Here we introduce a novel solid-state device which comprises two stacked nanopores defining the in- and outlet of a pico liter cavity. This pore-cavity-pore (PCP) architecture allows for the electrical as well as optical examination of single molecules. The PCP device is fabricated by structuring nanopores into a sandwich SiN/Si/SiN wafer using e-beam lithography, wet chemical etching, and feedback controlled electrochemical etching steps. The in- and outlet nanopores of the fabricated PCP-devices are characterized by transmission electron microscopy, evidencing that the pore diameters may be controlled independently down to 10 nm. Through electric potential control we are able to inject and eject nano-objects into and out of the device. We present fluorescence experiments of single DNA molecules and nm-sized polystyrene beads inside the PCP device. We study the potential-dependent loading and unloading of the cavity with 40 nm fluorescently labeled beads and analyze the diffusion of single particles within the cavity by particle tracking. We find that the apparent diffusion coefficients inside the cavity deviate from values obtained for free diffusion in solution and correlate the deviation with the confinement effect of the cavity. Moreover, we present experiments showing the trapping and translocation of fluorescently labeled DNA.