Novel Synthetic Nanopores for Single-Molecule Biosensing Applications

Abstract

Studying biomolecular systems at the single-molecule level in contrast to the ensemble-averaged measurement approaches has opened a new era in probing structural and dynamic properties of biomolecules. Nanopore biosensing technology (the youngest in this family) has been developed over the past two decades as a label-free, single-molecule sensing platform for biopolymers and small molecules. In nanopore-based sensing, as a biomolecule is pulled through a nanoscopic channel, either within a protein assembly embedded in an organic membrane (biological nanopore) or a synthetically-fabricated channel in a solid-state membrane (solid-state nanopore), partial physical obstruction of the pore is detected as a characteristic transient disruption in the ionic current. These signals are then compiled and statistical analysis is used to probe structural elements of the biomolecules. in solid-state nanopores, the total sensing resolution of a nanopore is defined by the geometry of the pore, i.e., a nanopore with diameter and thickness comparable to the structural element of the biomolecule being studied is required for the highest sensing resolution. Therefore, ultra-thin membranes of two-dimensional (2D) materials provide the highest resolution possible, surpassing that of protein nanopores, owing to their single or a few-atomic-layer thickness. Herein, we investigate the application of freestanding thin membranes of MXenes, an emerging family of 2D materials with a layered structure of transition metals carbides, nitrides, or carbonitrides, in nanopore technology. For biomolecular sensing, the synthetic membrane is fabricated in wafer-scale by the precise self-assembly of one-nanometer-thick MXene sheets. In addition, by harnessing the unique electrical and electrochemical properties of MXenes and their versatile chemistry to modify some fundamental components and characteristics of a traditional nanopore's sensing modality to eliminate the adverse effect of access resistance on smearing the sensing resolution, our proposed MXene-based nanopore platform could outperform existing nanopore sensing paradigms.