Related Experiment Video
Updated: Aug 13, 2026

Fine-tuning the Size and Minimizing the Noise of Solid-state Nanopores
Published on: October 31, 2013
Salt dependence of ion transport and DNA translocation through solid-state nanopores
Ralph M M Smeets1, Ulrich F Keyser, Diego Krapf
1Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands.
Abstract:
We report experimental measurements of the salt dependence of ion transport and DNA translocation through solid-state nanopores. The ionic conductance shows a three-order-of-magnitude decrease with decreasing salt concentrations from 1 M to 1 muM, strongly deviating from bulk linear behavior. The data are described by a model that accounts for a salt-dependent surface charge of the pore. Subsequently, we measure translocation of 16.5-mum-long dsDNA for 50 mM to 1 M salt concentrations. DNA translocation is shown to result in either a decrease ([KCl] > 0.4 M) or increase of the ionic current ([KCl] < 0.4 M). The data are described by a model where current decreases result from the partial blocking of the pore and current increases are attributed to motion of the counterions that screen the charge of the DNA backbone. We demonstrate that the two competing effects cancel at a KCl concentration of 370 +/- 40 mM.
Related Concept Videos
Pore Transport and Ion-Pair Transport
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...
Transcellular Transport of Solutes
Ion Channels
Ion channels are specialized integral membrane proteins on the plasma membrane that allow specific...
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Aquaporins
Osmosis and Osmotic Pressure of Solutions

