Despite the simplicity, more investigation is required to gain a fundamental understanding of the nanopore method. In particular, gaps remain in our knowledge of the dynamical processes that govern macromolecule translocation through a nanopore and the available methods for the fabrication of nanoscale materials.

Open questions

Presently, many questions on the nanopore influence on DNA translocation remain open. One of them is related to the influence of the surface state of the nanopore. In particular, the charge on the DNA translocation at a low salt concentration. In other words: what happens when the Debye length of an ionic solution becomes close to the nanopore diameter? Another is the influence of the charge and the hydrophobic character of the nanopore surface on the DNA translocation.

Investigating surface state

Here, researchers from IEM (ENSCM-Université de Montpellier-CNRS) Montpellier, France, ICSM (CEA-CNRS-ENSCM-Université de Montpellier) Bagnols-sur-Cèze, France and LSI (CEA-polytechnique) Orsay, France, collaborate. They investigate the influence of the nanopore surface state and the addition of Mg2+ on poly-adenosine translocation.

Controlling surface state

The researchers design the SiN nanopore using atomic layer deposition (ALD) to control both the surface state and the diameter. They find that if the nanopore and the polyA molecule exhibit a similar charge, the macromolecule velocity increases and its global energy barrier for entrance into the nanopore decreases. This is in opposition to the non-charged nanopore. Moreover, the addition of a divalent chelating cation induces an increase in the energy barrier.

More information about this research can be found in the journal article Nanotechnology 26 144001. The article is part of a focus collection on DNA sequencing.

Further reading

Nanopores form more quickly through FIB boiling (Jan 2014)
Using solid-state nanopores to examine proteins (Apr 2014)
Determining the translocation of nanoparticles (Apr 2014)