Molecular insights into geometric and electrophoretic effects on DNA translocation speed through graphene nanoslit sensor

Slowing down DNA translocation speeds through solid-state nanopores is of vital importance to detect temporal and electrical signals with single-base resolution. To control DNA translocation speed and maintain sequencing sensitivity, the graphene nanoslit sensor is proposed and molecular dynamics simulations are performed to investigate geometric and electrophoretic effects. Results show that the translocation speed is slowed down and the detection range of nanoslit sensors maintains when reducing nanoslit width. Energy barriers of translocation increase with a narrower width, while the ions flow remains because of invariant nanoslit length. Adjusting applied voltage can further control the translocation speed but in a non-linear way. Generally, the speed of a single-base translocation is expected to be well adjusted by integrating geometric and electrophoretic factors, which can separately result in a 66-fold and 25-fold de-speeding. Meanwhile, the distinguishability of the ionic current signal maintains. This study provides molecular insights in controlling translocation speed and sequencing DNA bases by nanoslit sensor. The unique geometry of nanoslit with two adjustable dimensions makes it a promising pore candidate for solid-state nanopore sequencing.