Unraveling single-stranded DNA in a solid-state nanopore.
Solid-state nanopores are an emerging class of single-molecule sensors. Whereas most studies so far focused on double-stranded DNA (dsDNA) molecules, exploration of single-stranded DNA (ssDNA) is of great interest as well, for example to employ such a nanopore device to read out the sequence. Here, we study the translocation of long random-sequence ssDNA through nanopores. Using atomic force microscopy, we observe the ssDNA to hybridize into a random coil, forming blobs of around 100 nm in diameter for 7 kb ssDNA. These large entangled structures have to unravel, when they arrive at the pore entrance. Indeed, we observe strong blockade events with a translocation time that is exponentially dependent on voltage, tau approximately e(-V/V(0)). Interestingly, this is very different than for dsDNA, for which tau approximately 1/V. We report translocations of ssDNA but also of ssDNA-dsDNA constructs where we compare the conductance-blockade levels for ssDNA versus dsDNA as a function of voltage.
Kowalczyk
Stefan W
SW
Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
Tuijtel
Maarten W
MW
Donkers
Serge P
SP
Dekker
Cees
C
D004247:DNA / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D010316:Particle Size
D004247:DNA