Protein Translocation through a MoS2 Nanopore:A Molecular Dynamics Study

Single-molecule protein sequencing is essential for a wide range of research and application fields, where the recently emerging 2D nanopores have open unprecedented possibilities. The protein translocating through a 2D nanopore plays vital roles in the nanopore-based analysis, where various detection or sequencing method could be employed. It is critically important to study the protein translocating through various 2D nanopores, which may help design efficient nanopore devices. However, few 2D materials other than graphene have been studied in this context yet. In this work, molecular dynamics (MD) simulations were employed to investigate the feasibility of single-molecule protein sequencing with a MoS2 nanopore. Both phenylalanine-glycine repeat peptides and a peptide with the sequence taken from the thioredoxin protein were studied in their extended unfolded state, which adsorbed onto the MoS2 membrane spontaneously. These peptides kept adsorbing onto MoS2 and permeated unidirectionally through the MoS2 nanopore, driven by either an electric field or hydrostatic pressure gradient. Their translocation process was stepwise, and the speed sensitively depended on the electric field, hydrostatic pressure, the charge density, or hydrophobicity of the peptides. The stepwise peptide translocation yielded ionic current blockades correlating with the sequence of peptide fragment in the nanopore. This work provides with insights for designing a protein-sequencing device with a MoS2 nanopore.