Modeling the conductance and DNA blockade of solid-state nanopores

TLDR

The study aims to measure and theoretically model ionic conductance and DNA‑induced blockade in solid‑state nanopores ranging from 5 to 100 nm in diameter, including an exact solution for hourglass‑shaped pores. Measurements of conductance and blockade were performed on solid‑state nanopores, and theoretical models—including an exact hourglass solution—were developed and compared to experimental data. The results show that access resistance is essential for accurate conductance predictions, the exact hourglass model matches measurements without adjustable parameters, DNA blockade decreases with pore diameter contrary to earlier models, and three blockade models all agree with the data.

Abstract

We present measurements and theoretical modeling of the ionic conductance G of solid-state nanopores with 5-100 nm diameters, with and without DNA inserted into the pore. First, we show that it is essential to include access resistance to describe the conductance, in particular for larger pore diameters. We then present an exact solution for G of an hourglass-shaped pore, which agrees very well with our measurements without any adjustable parameters, and which is an improvement over the cylindrical approximation. Subsequently we discuss the conductance blockade ΔG due to the insertion of a DNA molecule into the pore, which we study experimentally as a function of pore diameter. We find that ΔG decreases with pore diameter, contrary to the predictions of earlier models that forecasted a constant ΔG. We compare three models for ΔG, all of which provide good agreement with our experimental data.