Synchronous Optical and Electrical Measurements of Single DNA Molecules Translocating Through a Solid State Nanopore

Abstract

Nucleic acids and proteins are increasingly being analyzed using solid-state nanopores. The nanopore method relies on the measurement of transient conductance changes of the nanopores as charged biomolecules are being electrophoretically driven into it. Although electrical detection is highly appealing for the label-free analysis of biological samples, our understanding of the dynamics of charged biopolymers through such nanoconfined geometries is limited by the information captured by the electrical signal alone.We report the development of an instrument capable of interrogating solid-state nanopore devices by simultaneous electrical and optical measurements. Instead of the conventional TEM-drilled nanopores, we used a method pioneered by our group, and fabricate nanopores in a thin SiNx membrane via dielectric breakdown in solution . In this presentation, we show how a range of odd behaviors of the ionic current can be explained with parallel fluorescence imaging of the nanopore. Our custom instrument allows us to: (i) study these anomalous events; (ii) probe the dynamics of DNA capture; (iii) monitor, for the first time, the creation process of a nanopore; and (iv) determine its location on the dielectric membrane;.A better understanding of these anomalous single-molecule events during DNA passage through solid-state nanopores is essential to increase reliability of nanopore-based sensing.