Single-molecule DNA Translocation Through Si₃N₄- and Graphene Solid-state Nanopores Check Access

The controlled translocation of a single, double-stranded DNA (dsDNA) through a solid-state nanopore (NP) with optical tweezers (OT) is described in the presence of an electric field under buffer conditions. Upon threading dsDNA complexed by single proteins through a NP in 20 nm thick Si3N4-membranes, we find distinct asymmetric and retarded force signals that critically depend on the overall charge of the protein, the molecular elasticity of the dsDNA and the counter-ionic shielding of the polyelectrolyte (dsDNA) in the buffer3. This force response can be quantitatively simulated and understood within a theoretical model where an isolated charge on an elastic, polyelectrolyte strand experiences a harmonic nanopore potential during translocation. In order to extend these experiments to atomically thin solid-state NP, dsDNA was threaded through single nanolayer graphene NP by a transmembrane voltage.