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.