Clog and Release, and Reverse Motions of DNA in a Nanopore.

Motions of circular and linear DNA molecules of various lengths near a nanopore of 100 or 200 nm diameter were experimentally observed and investigated by fluorescence microscopy. The movement of DNA molecules through nanopores, known as translocation, is mainly driven by electric fields near and inside the pores. We found significant clogging of nanopores by DNA molecules, particularly by circular DNA and linear T4 DNA (165.

Gate-Voltage-Controlled Threading DNA into Transistor Nanopores.

We present a simple method for DNA translocation driven by applying AC voltages, such as square and sawtooth waves, on an embedded thin film as a gate electrode inside of a dielectric nanopore, without applying a conventional bias voltage externally across the pore membrane. Square waveforms on a gate can drive a single DNA molecule into a nanopore, which often returns from the pore, causing an oscillation across the membrane. An optimized sawtooth-like negative voltage pulse on the gate can thread a fraction of a DNA molecule into a pore after a single pulse.