Abstract

Coupling Photonic and Electrochemical Phenomena with Zero-Dimensional Nanofluidics

Paul Bohn, Arthur J. Schmitt Professor of Chemical and Biomolecular Engineering and Professor of Chemistry and Biochemistry, University of Notre Dame

The relationship between functional states of redox enzymes and the macroscopically observed phenotype is of fundamental importance to the chemistry of life. However, despite their fundamental importance in basic biochemical phenomena, the direct electrochemical observation of single electron transfer events in biological systems has eluded us until the recent advent of bifunctional nanoelectrochemical-nanophotonic nanopore arrays. High density recessed dual-ring electrode nanopores moderate the interaction between single electron-transfer events and fluorescence emission, in the zeptoliter optical confinement volume of a zero-mode waveguide (ZMW). The dual optical-electrochemical functionality makes it possible to perform single molecule spectroelectrochemical measurements under redox cycling conditions – both when the upper electrode is potential-controlled and using self-induced redox cycling. Single molecule cycling behavior is evidenced in the fluorescence dynamics. Capture efficiencies are characterized as a function of the potential applied to the upper ring electrode, and single molecule electrochemical-spectroscopic cross-correlation measurements are performed as a function of nanopore occupancy down to <n> ~0.001.