Silica Nanopores

 Nanotechnology develops small devices with dimensions below 100 nm, one hundred times smaller than the diameter of a human hair. Nanodevices can be used for a wide range of applications, such as biomedical sensors (see the Jan 2005 highlight) or tools for studying DNA properties (see the Feb 2009 highlight and the Nov 2005 highlight). In building and controlling such small devices, researchers run into problems such as surface effects and significant thermal fluctuations. Furthermore, properties arising from the discrete nature of matter start to dominate at the nanoscale, producing phenomena not observed in larger devices. For instance, when immersed in electrolytic solution and under the influence of an electric field, nanopores act as diodes for ionic currents, conducting in one voltage polarity better than the other, a behavior which has been proposed as the basis for developing nanoelectronic devices. In a recent report, researchers have studied this so-called rectification behavior by means of molecular dynamics simulations using the program NAMD, the ionic rectification inside the nanopore being described in atomic detail. More information can be found here. See also our recent biotechnology review.

Ionic current rectification through silica nanopores. Eduardo R. Cruz-Chu, Aleksei Aksimentiev, and Klaus Schulten. Journal of Physical Chemistry C, 113:1850-1862, 2009.