Solid State Nanopores for Selective Sensing of DNA - Nanopores: Sensing and Fundamental Biological Interactions - page 115

5.3.1 Nanopore Diameter Dependant Interactions

In the presence of a frictionless environment, the electrophoretic translocation of
DNA is independent of the SSN diameter. Hereitisalsoassumedthatthereare
no charges confined inside the nanopore, and length of the DNA strand does not
play any role in the translocation. In one of the previous reports, Cross et al.
proved that translocation of DNA did depend on the length of the DNA and
nanopore diameter [ 25 ]. They suggested that the notion of frictionless and free
electrophoresis did not exist in nanopores with diameters comparable to the size
of the DNA.
Iqbal and co-workers reported size dependant DNA translocations [ 27 ].
They simulated the effects of DNA diameter on translocation velocity, van der
Waals forces, and ionic current at higher applied voltage; these effects are shown in
Fig. 5.5 . The van der Waals forces decrease with increasing pore diameter due to

a b

Pore Diameter vs. vdW Force Pore Diameter vs. Velocity of DNA

1

0.12

0.1

0.9

0.08

0.8

0.06

0.7

0.04

0.6

0.02

0 0.5

10 15 20 25 30 35 40 10 15 20 25 30 35 40

Pore Diameter (angstrom)

Pore Diameter (angstrom)

c

Pore Diameter vs. Ionic Current

20

15

10

5

0

10 15 20 25 30 35 40

Pore Diameter (angstrom)

Fig. 5.5 Figure shows the effects of SSN diameter on (a) van der Waals force (b) velocity of
translocation and (c) ionic current [ 27 ]. Reprinted by permission from New World Publishing
International: American Journal of Biomedical Sciences, copyright (2009)