Single-File Protein Translocations through Graphene-MoS₂ Heterostructure Nanopores

Successfully threading unfolded protein molecules through nanopores whose sizes are comparable to that of an amino acid is a prerequisite for the nanopore-based protein sequencing method that promises to be high-throughput and low-cost. While the electric driving method can be effective for a homogeneously charged DNA molecule, it fails to drive an unfolded protein through a nanopore because the net charge of a protein fragment inside of the pore (where the electric field exists) can be positive, negative, or neutral. Here we propose and demonstrate by molecular dynamics simulations protein transport through a nanopore in a quasi-two-dimensional heterostructure stacked together by graphene and molybdenum disulfide (MoS2) nanosheets. Thanks to different van der Waals interactions (U) between a protein molecule and different 2D surfaces, it is energetically favorable for protein to progressively move from the MoS2 surface to the graphene surface (more negative U) through a nanopore in the heterostructure.