First-passage-time analysis of DNA translocation in solid-state nanopores

We report a DNA translocation experiment using solid-state nanopores and 48 kb lambda DNA samples. As reported previously, the DNA translocation dynamics in such standard solid-state nanopore experiments appear to be complex and multiple folded translocation pathways are observable. We use the translocation events with little or no detectable folded structures to construct a distribution function for the DNA translocation times. We find that the translocation time distribution can be fitted using the first-passage-time probability density function derived by Schrodinger for 1-D Brownian motion with a drift. The voltage dependence of the extracted DNA drift velocity shows excellent agreement with the Stokes' law at high voltages. Deviation from the Stokes' law is found at low voltages, but can be attributed to a systematic error in how different types of folded DNA translocations are sorted.