The interrogation of single entities and events has been revolutionized by the introduction of methods to limit background. One powerful set of methods limits the volume interrogated to a very small region around the entity of interest. Here we describe a unique multifunctional architecture – the electrochemical zero-mode waveguide (E-ZMW) - capable of both optical spectroscopic and electrochemical studies of immobilized and freely diffusing redox-active single entities from molecules to nanoparticles to single bacterial cells. E-ZMWs are zeptoliter-volume bimodal nanoelectrochemical-nanophotonic pores supporting from one to three vertically separated recessed annular electrodes. They provide a link between single electron-transfer events and spectroscopic events, such as the fluorigenic 2e-/2H+ redox chemistry of flavins, e.g. FAD/FADH2, and simultaneous in situ single entity SERS and amperometry. Thus, the combination of electrochemical and spectroscopic measurements at the single entity level is a new tool for the characterization of single entity dynamics, allowing observation of phenomena such as population fluctuations, voltage-gated permselective access of single entities to the interior of the nanopore, and subsequent behavior of single entities in confined volumes.

Electrochemical zero-mode waveguide nanovials for capture and bimodal interrogation of single entities

2019 Fall National Meeting

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