Locking ssDNA in a Graphene-Terraces Nanopore and Steering Its Step-by-Step Transportation via Electric Trigger

This study demonstrates that the nanopore terraces constructed on a multilayer graphene sheet could be employed to con-trol the conformation and transportation of an ssDNA for nanopore sequencing. As adsorbed on a terraced graphene na-nopore, the ssDNA has no in-plane swing nearby the nanopore, and can be locked on graphene terraces in a stretched con-formation. Under biasing, the accumulated ions near the nanopore promote the translocation of the locked ssDNA, and also disturb the balance between the driven force and resistance force acted on the nucleotide in pore. A critical force is found to be necessary in trigging the kickoff of the ssDNA translocation, implying an inherent field effect of the terraced graphene nanopore. By changing the intensities of electric field as trigger signal, the stop and go of an ssDNA in the nanopore are manipulated at single nucleobase level. The velocity of ssDNA in the nanopore can also be regulated by the frequency of the electro-stimulations. As a result, a new scheme of controllable translocation of ssDNA in graphene nanopores is realized by introducing controllers and triggers, appealing more explorations in experiment.