  DNA capture with high fidelity is an essential part of nanopore
translocation. We report several important aspects of the capture process and
subsequent translocation of a model DNA polymer through a solid-state nanopore
in presence of an extended electric field using the Brownian dynamics
simulation that enables us to record statistics of the conformations at every
stage of the translocation process. By releasing the equilibrated DNAs from
different equipotentials, we observe that the capture time distribution depends
on the initial starting point and follows a Poisson process. The field gradient
elongates the DNA on its way towards the nanopore and favors a successful
translocation even after multiple failed threading attempts. Even in the limit
of an extremely narrow pore, a fully flexible chain has a finite probability of
hairpin-loop capture while this probability decreases for a stiffer chain and
promotes single file translocation. Our in silico studies identify and
differentiate characteristic distributions of the mean first passage time due
to single file translocation from those due to translocation of different types
of folds and provide direct evidences of the interpretation of the
experimentally observed folds [M. Gershow et al., Nat. Nanotech. 2, 775 (2007)
and M. Mihovilovic et al. Phys. Rev. Letts. 110, 028102 (2013)] in a solitary
nanopore. Finally, we show a new finding, - that a charged tag attached at the
$5^{\prime}$ end of the DNA enhances both the multi-scan rate as well as the
uni-directional translocation ($5^{\prime} \rightarrow 3^{\prime}$) probability
that would benefit the genomic barcoding and sequencing experiments.

Soft Condensed Matter;Biological Physics