Slowing Down DNA Translocation through Solid-State Nanopores by Edge-Field Leakage

Abstract Solid-state nanopores allow high-throughput single-molecule detection but identifying and even registering all translocating small molecules remain key challenges due to their high translocation speeds. We show here the same electric field that drives the molecules into the pore can selectively pin and delay their transport. A thin high-permittivity dielectric coating on slender bullet-shaped polymer nanopores permits electric field leakage at the pore tip to produce a voltage-dependent surface field on the upper periphery of the pore that can reversibly edge-pin entering molecules that can absorb conformally to the tip corner. This localized tip field renders molecular entry an activated process with sensitive exponential dependence on the bias voltage and molecular rigidity. The exponential sensitivity allows us to selectively prolong the translocation time of short single-stranded DNA molecules by up to 5 orders of magnitude, allowing discrimination against their double-stranded duplexes with 97% confidence. We show evidence that the leak-field pinned single-stranded DNA actually absorbs onto the edge before entering the pore, yielding translocation times as long as minutes.