Control of particle trapping in solid-state nanopores with magnetic functionalities: an overview

In the last decade, solid-state nanopores have been intensively investigated as label-free detectors of for single biological entities, such as protein chains or DNA molecules. With this approach, single entities are typically driven through a nanopore by applying an external electrical potential. However, this method cannot enable control over the speed of translocation, thus limiting the signal integration time. The most explored approach to introduce control of the translocation speed is based on trapping. In particular, a long acquisition time can be obtained by trapping a nanoparticle tagged with molecules close to a nanopore. The trapping phenomena can be generated by means of external stimuli such as light excitation and magnetic field application, obtaining respectively the so-called optical and magnetic trapping. Magnetic trapping, in particular, has been less explored but can be a useful approach to obtain very large trapping forces without interfering with other optical exitations that can be used for spectroscopic purposes. Here, we will briefly summarize the major examples of magnetic trapping approaches reported so far in solid-state nanopore technology.