Geometrical Effect in 2D Nanopores

Abstract

A long-standing problem in the application of solidstate nanopores is the lack of the precise control over the geometry of artificially formed pores compared to the well-defined geometry in their biological counterpart, that is, protein nanopores. To date, experimentally investigated solid-state nanopores have been shown to adopt an approximately circular shape. In this Letter, we investigate the geometrical effect of the nanopore shape on ionic blockage induced by DNA translocation using triangular h-BN nanopores and approximately circular molybdenum disulfide (MoS 2 ) nanopores. We observe a striking geometrydependent ion scattering effect, which is further corroborated by a modified ionic blockage model. The well-acknowledged ionic blockage model is derived from uniform ion permeability through the 2D nanopore plane and hemisphere like access region in the nanopore vicinity. On the basis of our experimental results, we propose a modified ionic blockage model, which is highly related to the ionic profile caused by geometrical variations. Our findings shed light on the rational design of 2D nanopores and should be applicable to arbitrary nanopore shapes.

Comparing current noise in biological and solid-state nanopores

“…For biological nanopores, a DNA-translocating motor protein (such as a helicase or polymerase) has been used to slowly feed a ssDNA strand into a protein pore for DNA sequencing [13][14][15] . For solid-state nanopores fabricated in thin SiNx membranes [16][17][18] or 2D materials (graphene [19][20][21] , boron nitride [22][23][24] , molybdenum disulfide [25][26][27] ), various efforts have been made to either increase time resolution 16,17,[28][29][30][31] , or slow down the translocation process 32 by the use of ionic liquids 27 , pore surface engineering 33 , mechanical manipulation with a double pore system 34 , and optical trapping 35 . Nevertheless, the SNR has not yet allowed de novo DNA sequencing with solid-state pores.…”

2D nanoporous membrane for cation removal from water: Effects of ionic valence, membrane hydrophobicity, and pore size

“…Feng et al 21 have also developed a scalable method to controllably make nanopores in single-layer MoS 2 with subnanometer precision using the electrochemical reaction (ECR). Recently, Liu and colleagues 22 investigated the geometrical effect of the nanopore shape on ionic blockage induced by DNA translocation through h-BN and MoS 2 nanopores. They observed a geometry-dependent ion scattering effect and further proposed a modified ionic blockage model which is highly related to the ionic profile caused by geometrical variations.…”

Probing DNA Translocations with Inplane Current Signals in a Graphene Nanoribbon with a Nanopore

“…Various attempts have been reported on the use of graphene and related layered materials to probe DNA, with partial success. 9 − 20 Individual DNA molecules could well be distinguished but challenges remain. For example, detailed features were hard to resolve because the ionic currents through these nanopores exhibited high levels of 1/f-noise.…”