Title: Coupling of Independent Electrochemical Reactions and Fluorescence at Closed Bipolar Interdigitated Electrode Arrays

Abstract

Electrochemical reactions occurring at the opposite ends of bipolar electrodes (BPEs) are necessarily coupled, enabling electron transfer events at one end to be read out optically, for example, by coupling to fluorogenic reactions at the other end. In order to explore the potential of this technique for studying multiple redox events, arrays of parallel BPE interdigitated electrode arrays (IDEAs) were fabricated and integrated with separate analytical and reporter microfluidic channels, respectively, in a closed BPE configuration. The apparatus was initially evaluated employing Fe(CN) ₆ ^3/4- in the analytical channel coupled to weakly emissive resazurin and strongly emissive resorufin as the fluorogenic redox reporter pair. We then used the device to investigate a proton-coupled electron transfer reaction, hydroquinone (QH ₂) oxidation, in structures with an integrated pH modulation electrode (PME). A pH-sensitive dye, fluorescein, was co-introduced into the analytical channel to monitor PME modulation of solution pH, and its coupling to QH ₂ oxidation, thereby permitting changes in solution pH, and consequently QH ₂ oxidation rate, to be monitored directly in the analytical channel and compared to the fluorescence in the reporter channel. Additionally, diffusion of OH ^- generated at the PME produced a spatial pH profile that was visualized viamore » fluorescein emission, and, because the oxidation of QH ₂ at each BPE is strongly dependent on the local pH, via the coupled fluorogenic reaction at the opposite pole of the corresponding BPE digit in the reporter channel. Thus, BPE IDEAs support the coupling of independent redox reactions and the use of fluorescence imaging to explore a diverse set of spatially varying electrochemical phenomena realized in a variety of electrochemical geometries.« less

Authors:

Xu, Wei ^[1]; Ma, Chaoxiong ^[1]; Bohn, Paul W. ^[2]

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+ Show Author Affiliations

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 and Dept. of Chemical and Biomolecular Engineering

Publication Date:

2015-10-22

Research Org.:

Univ. of Notre Dame, IN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1371715

Grant/Contract Number:  

FG02-07ER15851

Resource Type:

Journal Article: Accepted Manuscript

Journal Name:

ChemElectroChem

Additional Journal Information:

Journal Volume: 3; Journal Issue: 3; Journal ID: ISSN 2196-0216

Publisher:

ChemPubSoc Europe

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY