The distribution of DNA translocation times in solid-state nanopores

Abstract

This paper systematically investigates the effects of solution viscosity, applied voltageand DNA chain length on the distribution of DNA translocation times through8 ± 2 nm diameter silicon nitride nanopores. Linear dsDNA translocation events were selectedbased on the magnitude of current blockage and accumulated into scatter plotsof current blockage and event duration (translocation time). The translocationtime distribution was fitted to the solution of a Smoluchowski-type equation for1D biased diffusion to a sink. The DNA drifting speed under bias and diffusionconstant were extracted from the fits as functions of solution viscosity, appliedvoltage and DNA chain length. Combined with the Einstein–Smoluchowski relation,this model allowed evaluation of the viscous drag force on DNA molecules. Thismodel also allowed estimation of the uncertainty in determining the DNA chainlength due to the influence of friction on the spread of translocation times in ananopore measurement. The data analysis suggests that the simple 1D biaseddiffusion model fits the experimental data well for a wide range of conditions. Somedeviations from predicted behavior were observed and show where additionalphenomena are likely to contribute to the distribution of DNA translocation times.