Better than graphene?

ACS Nano http://doi.org/trz (2014)

Nanometre-sized holes in a membrane could potentially be used to sequence DNA quickly and at low cost by threading single strands of the molecule through the pores under an applied potential; the DNA bases are read by measuring modulations in the ionic current passing through the pore or with the help of a transverse tunnelling current. These nanopores are typically made from solid-state materials such as silicon nitride or are biological nanopores such as α-haemolysin. Recently, graphene-based devices have also been explored, which could provide single-base resolution because of the atomic thickness of the material. Narayana Aluru and colleagues at the University of Illinois at Urbana-Champaign now suggest that MoS₂ could in fact be a better choice of two-dimensional material for creating nanopores.

The researchers used molecular dynamics simulations to explore the translocation of double-stranded DNA through a MoS₂ nanopore with a diameter of 2.3 nm. Distinct ionic current signals for each of the four DNA bases were observed, and a signal-to-noise ratio of around 15 was calculated. In comparison, the signal-to-noise ratio for graphene nanopores was calculated to be around 3. Furthermore, the simulations showed that, whereas bases stick to graphene during translocation, DNA does not adhere to the MoS₂ nanopores. Aluru and colleagues also illustrate — with the help of density functional theory simulations — that MoS₂ nanopore devices could potentially be used to detect bases via transverse tunnelling measurements.