Single-Molecule Sensing Using Nanopores in Two-Dimensional Transition Metal Carbide (MXene) Membranes.

Label-free nanopore technology for sequencing biopolymers such as DNA and RNA could potentially replace existing methods if improvements in cost, speed, and accuracy are achieved. Solid-state nanopores have been developed over the past two decades as physically and chemically versatile sensors that mimic biological channels, through which transport and sequencing of biomolecules have already been demonstrated. Of particular interest is the use of two-dimensional (2D) materials as nanopore substrates, since these can in theory provide the highest resolution readout (<1 nm of a biopolymer segment) and opportunities for electronic multiplexed readout through their interesting electronic properties. In this work, we report on nanopores comprising atomically thin flakes of 2D transition metal carbides called MXenes. We demonstrate a high-yield (60%), contamination-free, and alignment-free transfer method that involves their self-assembly at a liquid-liquid interface to large-scale (mm-sized) films composed of sheets, followed by nanopore fabrication using focused electron beams. Our work demonstrates the feasibility of MXenes, a class of hydrophilic 2D materials with over 20 compositions known to date, as nanopore membranes for DNA translocation and single-molecule sensing applications.