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Observing the Reversible Single Molecule Electrochemistry of Alexa Fluor 647 Dyes by Total Internal Reflection Fluorescence Microscopy
Author(s) -
Fan Sanjun,
Webb James E. A.,
Yang Ying,
Nieves Daniel J.,
Gonçales Vinicius R.,
Tran Jason,
Hilzenrat Geva,
Kahram Mohaddeseh,
Tilley Richard D.,
Gaus Katharina,
Gooding J. Justin
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201907298
Subject(s) - alexa fluor , total internal reflection fluorescence microscope , fluorescence , chemistry , fluorophore , microscopy , fluorescence microscope , photochemistry , analytical chemistry (journal) , indium tin oxide , electrode , optics , chromatography , physics
Alexa Fluor 647 is a widely used fluorescent probe for cell bioimaging and super‐resolution microscopy. Herein, the reversible fluorescence switching of Alexa Fluor 647 conjugated to bovine serum albumin (BSA) and adsorbed onto indium tin oxide (ITO) electrodes under electrochemical potential control at the level of single protein molecules is reported. The modulation of the fluorescence as a function of potential was observed using total internal reflectance fluorescence (TIRF) microscopy. The fluorescence intensity of the Alexa Fluor 647 decreased, or reached background levels, at reducing potentials but returned to normal levels at oxidizing potentials. These electrochemically induced changes in fluorescence were sensitive to pH despite that BSA‐Alexa Fluor 647 fluorescence without applied potential is insensitive to pH between values of 4–10. The observed pH dependence indicated the involvement of electron and proton transfer in the fluorescence switching mechanism.