Influence of Pressure-Induced Fluid Flow on DNA Translocation Dynamics in Solid-State Nanopores

We studied the translocation dynamics of DNA through solid-state nanopores under the influence of an electrokinetic driving force and a pressure-driven fluid flow. Through the use of long, λ-DNA molecules, we sought to probe conformation-dependent translocation modes that were not observable in the pioneering experiments of Lu et al. (Nano Lett. 2013 Jul 10; 13(7): 3048–3052) on short molecules. We fabricated nanopores in 10-nm thick SiN membrane using the controlled dielectric breakdown (CBD) technique, which gave useable nanopores about 90% of the time. Then a pressure difference was applied across the nanopore to provide a drag force to counter the electrokinetic driving force. We monitored the disruptions of the ionic current through the nanopore and studied the influence of the applied pressure on the distribution of translocation times and the integrated charge deficits (ECDs) of λ-DNA translocations. We present the results of measurements with applied pressures ranging from 0 to 300 kPa and a theoretical analysis that models the initial polymer configurations and the fluid and electrokinetic force profiles.