Discrimination of equi-sized nanoparticles by surface charge state using low-aspect-ratio pore sensors

In the field of nanopore sensing, it is difficult to distinguish particles of similar sizes by the ionic current signatures. In contrast, here, we demonstrated discrimination of equi-sized polystyrene ( PS) particles by utilizing a low thickness-to-diameter aspect-ratio nanopore. We found distinct changes of the ionic current through the pore associated with translocation of PS particles modified with different functional groups. Comparing results about different size of nanopore can lead to discrimination of their surface charge densities. This discrimination technique may be useful in the development of low-aspect-ratio nanopore sensors for bioanalysis. (C) 2014 AIP Publishing LLC.