By actively detecting the passage of an individual DNA molecule as it passes through the nanopore and quickly reversing the electric field, single molecules can be recaptured over 1000 times. This allows the researchers to obtain statistics on the translocation process for an individual DNA molecule. The technique reveals short translocation times and very strong folding when molecules are recaptured at timescales below their characteristic "Zimm" relaxation time. At longer recapture times, when the molecule has had sufficient time to relax, these values approach those seen in non-recapture experiments.

These insights into a novel, so-far not well explored non-equilibrium regime, means that researchers can assess the importance of the (non)equilibrium state of the molecule during translocation processes. Furthermore, such repeated interrogation of single-molecules could allow for more accurate measurements and might be used in the future to explore time-dependent processes.

More information can be found in the journal Nanotechnology (in press).

Further reading

Enhanced model describes conductance and DNA blockade of nanopores (Jul 2011)
Graphene could revolutionize DNA sequencing (Jul 2010)
Nanopores sequence DNA (Oct 2009)