Abstract

Bipolar Electrode Coupling of Nanoscale Electron Transfer Reactions to Remote Chromogenic and Luminogenic Reporter Reactions

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

The combination of fluorescence and absorption spectroscopy with electrochemistry presents new avenues for the study of redox reactions, with potential for enhanced throughput, sensitivity, and spatial resolution.  Here we present a novel configuration for coupling high sensitivity voltammetric measurements implemented in nanoscale architectures - such as nanopore-confined recessed ring-disk electrode arrays - with remote electrochemically-triggered chromogenic and fluorigenic reporter reactions.  Coupling is mediated by a mm-scale bipolar electrode which communicates the local solution potential in the analyte-measuring portion of the device to an opposing chromogenic or fluorigenic reporter reaction in a remote location.  Oxidation (reduction) of reversible analytes at the disk working electrode is accompanied by reduction (oxidation) on the nanopore portion of the bipolar electrode and then monitored by the accompanying oxidation of the reporter to produce a change in color or luminescence.  The remote end of the bipolar electrode is placed in a cell far from the nanopore ring-disk array so that highly efficient reporter measurements can be carried out conveniently against low intrinsic backgrounds.  The combination of bipolar eletrodes with luminescence in the dihydroresorufin/resorufin system has been used to study in situ generation of H₂O₂ in electrokinetic flow and for analytical  determinations down to pM limits of detection.  Applications of chromogenic reporter reactions for point-of-care (POC) use will also be described.