Nanopores in Two-Dimensional Materials for High-Resolution Biomolecular Sensing

Nanopore technology has revolutionized single-molecule biomolecular analysis by providing researchers with an inexpensive, rapid, and high-throughput tool for sensing and sequencing biopolymers (DNA, RNA, and proteins). In this technique, as a biomolecule is electrokinetically pulled through a nanometer-sized pore, either within a biological or synthetic nanopore, partial physical obstruction of the nanopore is detected as a characteristic transient disruption in the ionic current. For sequencing, each unique set of building blocks produces a distinct ionic current level detected using a high-bandwidth current reader. The chronological appearance of different signal levels as a molecular strand is passed through the pore reveals the sequence of that strand. A hallmark feature of the nanopore technique is the dependence of the sensing resolution on the geometry of the nanopore (diameter and thickness in solid-state nanopores). Therefore, theoretically, two-dimensional (2D) materials afford the highest resolution possible, owing to their single to a few-atomic-layer thickness. However, practically, a phenomenon known as “access resistance” renders nanopore resolution broader than the physical pore thickness and reduces the sensing resolution¹. To date, no solid-state nanopore has sequenced a biopolymer, because of material properties limitations and difficulties of making small 2D nanopores. I will discuss progress in fabricating nanopores in various materials including van der Waals 2D materials (MoS₂) and the more hydrophilic MXenes, a new family of 2D transition metals carbides, nitrides, or carbonitrides². We have recently implemented MXene nanopores for biomolecule sensing³ and developed a method to produce a large-scale MXene monolayer film⁴. I will discuss how use of ion intercalating MXenes can be useful for nanopore-based biomolecule sequencing, and the requirements of such a device.<br/><br/>1. Comer et al., Nanoscale 8, 9600 - 9613 (2016).<br/>2. Vahid Mohammadi et al., Science 372, 1165 (2021).<br/>3. Mojtabavi et al., ACS Nano 13, 3042 - 3053 (2019).<br/>4. Mojtabavi et al., ACS Nano, 15, 625 - 636 (2021)