Self-induced redox cycling coupled luminescence on nanopore recessed disk-multiscale bipolar electrodes

Journal Article · Wed Mar 25 00:00:00 EDT 2015 · Chemical Science

DOI:https://doi.org/10.1039/c5sc00433k· OSTI ID:1371875

Ma, Chaoxiong ^[1]; Zaino III, Lawrence P. ^[1]; Bohn, Paul W. ^[2]

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1. Univ. of Notre Dame, IN (United States). Dept. of Chemistry and Biochemistry
2. Univ. of Notre Dame, IN (United States). Dept. of Chemistry and Biochemistry; Univ. of Notre Dame, IN (United States). Dept. of Chemical and Biomolecular Engineering

Self-induced redox cycling at nanopore ring-disk electrodes is coupled, through a bipolar electrode, to a remote fluorigenic reporter reaction. We present a new configuration for coupling fluorescence microscopy and voltammetry using self-induced redox cycling for ultrasensitive electrochemical measurements. An array of nanopores, each supporting a recessed disk electrode separated by 100 nm in depth from a planar multiscale bipolar top electrode, was fabricated using multilayer deposition, nanosphere lithography, and reactive-ion etching. Self-induced redox cycling was induced on the disk electrode producing ~30× current amplification, which was independently confirmed by measuring induced electrogenerated chemiluminescence from Ru(bpy)₃^2/3+/tri-n-propylamine on the floating bipolar electrode. In this design, redox cycling occurs between the recessed disk and the top planar portion of a macroscopic thin film bipolar electrode in each nanopore. Electron transfer also occurs on a remote (mm-distance) portion of the planar bipolar electrode to maintain electroneutrality. This couples the electrochemical reactions of the target redox pair in the nanopore array with a reporter, such as a potential-switchable fluorescent indicator, in the cell at the distal end of the bipolar electrode. Oxidation or reduction of reversible analytes on the disk electrodes were accompanied by reduction or oxidation, respectively, on the nanopore portion of the bipolar electrode and then monitored by the accompanying oxidation of dihydroresorufin or reduction of resorufin at the remote end of the bipolar electrode, respectively. In both cases, changes in fluorescence intensity were triggered by the reaction of the target couple on the disk electrode, while recovery was largely governed by diffusion of the fluorescent indicator. Reduction of 1 nM of Ru(NH₃)₆³⁺ on the nanoelectrode array was detected by monitoring the fluorescence intensity of resorufin, demonstrating high sensitivity fluorescence-mediated electrochemical sensing coupled to self-induced redox cycling.

• Research Organization: Univ. of Notre Dame, IN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER); National Science Foundation (NSF)
• Grant/Contract Number: SC0006642; NSF1404744
• OSTI ID: 1371875
• Journal Information: Chemical Science, Vol. 6, Issue 5; ISSN 2041-6520
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

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