Graphene-MoS₂ Heterojunction Nanopores: Enhanced ssDNA Capture via Asymmetric Charge Control

DNA sequencing through nanopores requires both high-throughput detection and precise timing control. However, single-material nanopores face conflicting demands regarding capture efficiency and translocation control. To tackle these challenges, all-atom molecular dynamics (MD) simulations were performed to study a graphene-MoS₂ heterojunction nanopore with asymmetric charge control. The simulations revealed that under negative surface charging, the concentration of K⁺ ions increases to 6.17 times the bulk value on the graphene side, while it only reaches 1.45 times the bulk value on the neutral MoS₂ side. This negative charging enhances the capture probability of single-stranded DNA (ssDNA) from 16.67% to 35.0% and increases the capture of terminal nucleotides from 1.67% to 10.0%. These findings suggest that negative charging creates more favorable orientations for the sequential translocation of ssDNA. Within the nanopore, the negative charging generates a stronger electroosmotic force that counteracts the electrophoretic force. This interaction leads to a prolonged residence time and reduced force fluctuations during translocation. Overall, these results provide valuable design principles for developing heterojunction nanopores suitable for nanopore-based single-molecule sequencing.