8 research outputs found
Identification of single nucleotides in MoS2 nanopores
Ultrathin membranes have drawn much attention due to their unprecedented
spatial resolution for DNA nanopore sequencing. However, the high translocation
velocity (3000-50000 nt/ms) of DNA molecules moving across such membranes
limits their usability. To this end, we have introduced a viscosity gradient
system based on room-temperature ionic liquids (RTILs) to control the dynamics
of DNA translocation through a nanometer-size pore fabricated in an atomically
thin MoS2 membrane. This allows us for the first time to statistically identify
all four types of nucleotides with solid state nanopores. Nucleotides are
identified according to the current signatures recorded during their transient
residence in the narrow orifice of the atomically thin MoS2 nanopore. In this
novel architecture that exploits high viscosity of RTIL, we demonstrate
single-nucleotide translocation velocity that is an optimal speed (1-50 nt/ms)
for DNA sequencing, while keeping the signal to noise ratio (SNR) higher than
10. Our findings pave the way for future low-cost and rapid DNA sequencing
using solid-state nanopores.Comment: Manuscript 24 pages, 4 Figures Supporting Information 24 pages, 12
Figures, 2 Tables Manuscript in review Nature Nanotechnology since May 27th
201
Measurement of the Position-Dependent Electrophoretic Force on DNA in a Glass Nanocapillary
The electrophoretic force on a single DNA molecule inside a glass nanocapillary depends on the opening size and varies with the distance along the symmetrical axis of the nanocapillary. Using optical tweezers and DNA-coated beads, we measured the stalling forces and mapped the position-dependent force profiles acting on DNA inside nanocapillaries of different sizes. We showed that the stalling force is higher in nanocapillaries of smaller diameters. The position-dependent force profiles strongly depend on the size of the nanocapillary opening, and for openings smaller than 20 nm, the profiles resemble the behavior observed in solid-state nanopores. To characterize the position-dependent force profiles in nanocapillaries of different sizes, we used a model that combines information from both analytical approximations and numerical calculations
Nanopore integrated nanogaps for DNA detection
International audienc
Nanopore Integrated Nanogaps for DNA Detection
A high-throughput fabrication of
sub-10 nm nanogap electrodes combined
with solid-state nanopores is described. These devices should allow
concomitant tunneling and ionic current detection of translocating
DNA molecules. We report the optimal fabrication parameters in terms
of dose, resist thickness, and gap shape that allow easy reproduction
of the fabrication process at wafer scale. The device noise and current
voltage characterizations performed and the influence of the nanoelectrodes
on the ionic current noise is identified. In some cases, ionic current
rectification for connected or biased nanogap electrodes is also observed.
In order to increase the extremely low translocation rates, several
experimental strategies were tested and modeled using finite element
analysis. Our findings are useful for future device designs of nanopore
integrated electrodes for DNA sequencing