Nanopore-Based DNA Sequencing and DNA Motion Control - Nanopores: Sensing and Fundamental Biological Interactions - page 266

Fig. 11.12 Transverse current vs. time (in arbitrary units) of a highly idealized single strand of
DNA translocating through a nanopore with a constant motion. The sequence of the single strand is
AGCATCGCTC. The left inset shows a top-view schematic of the pore cross section with four
electrodes. The right inset shows an atomistic side view of the idealized single strand of DNA and
one set of gold electrodes across which electrical current is calculated. The boxes show half the
time each nucleotide spends in the junction. Within each box, a unique signal from each of the
bases can be seen. Image adapted from [ 19 ]
Fig. 11.13 Center panel : schematic diagram of a novel biosensor consisting of a nanopore in a
capacitor membrane. Right panel : high-resolution TEM image through the capacitor membrane
structure. Left panel : high-resolution lattice image of a nanopore sputtered into the capacitor
membrane. Image adapted from [ 21 ]
The high spatial resolution can be achieved by using a thin gate oxide, such as
0.7 nm in the standard MOSFET technology, so condition (2) can be satisfied. For
condition (3), MD simulation was done by Gracheva et al . [ 24 ] showing that it is
possible to resolve individual nucleotides as well as their types in the absence of
conformational disorder (Fig. 11.15 ). However, avoiding conformational disorders
and controlling the position of the DNA (against thermal agitation) remains a
serious challenge from an experimental point of view. Some of these issues will
be discussed in Section 11.2.