Coupling Electrochemistry with Fluorescence Confocal Microscopy To Investigate Electrochemical Reactivity: A Case Study with the Resazurin-Resorufin Fluorogenic Couple

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• 作者：Thomas Doneux ; Laurent Bouffier ; Bertrand Goudeau ; Stéphane Arbault
• 刊名：Analytical Chemistry
• 出版年：2016
• 出版时间：June 21, 2016
• 年：2016
• 卷：88
• 期：12
• 页码：6292-6300
• 全文大小：503K
• 年卷期：0
• ISSN：1520-6882

文摘

The redox couple resazurin-resorufin exhibits electrofluorochromic properties which are investigated herein by absorption and fluorescence spectroelectrochemistry and by electrochemically coupled-fluorescence confocal laser scanning microscopy (EC-CLSM). At pH 10, the highly fluorescent resorufin dye is generated at the electrode surface by the electrochemical reduction of the poorly fluorescent resazurin. Performing EC-CLSM at electrode surfaces allows to monitor spatially resolved electrochemical processes in situ and in real time. Using a small (315 μm diameter) cylindrical electrode, a steady-state diffusion layer builds up under potentiostatic conditions at −0.45 V vs Ag|AgCl. Mapping the fluorescence intensity in 3D by CLSM enables us to reconstruct the relative concentration profile of resorufin around the electrode. The comparison of the experimental diffusion-profile with theoretical predictions demonstrates that spontaneous convection has a direct influence on the actual thickness of the diffusion layer, which is smaller than the value predicted for a purely diffusional transport. This study shows that combining fluorescence CLSM with electrochemistry is a powerful tool to study electrochemical reactivity at a spatially resolved level.