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Linking Single-Molecule Blinking to Chromophore Structure and Redox Potentials

Authors

  • Ingo H. Stein,

    1. NanoBioScience Group, Institute for Physical and Theoretical Chemistry, TU Braunschweig, Hans-Sommer-Str. 10, 38106 Braunschweig (Germany)
    2. Applied Physics-Biophysics & Center for NanoScience (CeNS), Ludwig Maximilian University, Amalienstr. 54, 80799 München (Germany)
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  • Stella Capone,

    1. Applied Physics-Biophysics & Center for NanoScience (CeNS), Ludwig Maximilian University, Amalienstr. 54, 80799 München (Germany)
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  • Jochem H. Smit,

    1. Molecular Microscopy Research Group & Single-molecule Biophysics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
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  • Fabian Baumann,

    1. Applied Physics-Biophysics & Center for NanoScience (CeNS), Ludwig Maximilian University, Amalienstr. 54, 80799 München (Germany)
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  • Dr. Thorben Cordes,

    Corresponding author
    1. Molecular Microscopy Research Group & Single-molecule Biophysics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
    • Molecular Microscopy Research Group & Single-molecule Biophysics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
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  • Prof. Dr. Philip Tinnefeld

    Corresponding author
    1. NanoBioScience Group, Institute for Physical and Theoretical Chemistry, TU Braunschweig, Hans-Sommer-Str. 10, 38106 Braunschweig (Germany)
    2. Applied Physics-Biophysics & Center for NanoScience (CeNS), Ludwig Maximilian University, Amalienstr. 54, 80799 München (Germany)
    • NanoBioScience Group, Institute for Physical and Theoretical Chemistry, TU Braunschweig, Hans-Sommer-Str. 10, 38106 Braunschweig (Germany)
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Abstract

Intensity fluctuations between an ON-state and an OFF-state, also called blinking, are common to all luminescent objects when studied at the level of individuals. We studied blinking of three dyes from a homologous series (Cy3, Cy5, Cy7). The underlying radical anion states were induced by removing oxidants (i.e. oxygen) and by adding the reductant ascorbic acid. We find that for different conditions with distinct levels of oxidants in solution the OFF-state lifetime always increases in the order Cy3<Cy5<Cy7. Longer OFF-times are related to higher reduction potentials of the fluorophores, which increase with the size of the chromophore. Interestingly, we find reaction rates of the radical anion that are unexpectedly low at the assumed oxygen concentration. On the other hand, reaction rates meet the expectations of similar Rehm–Weller plots when methylviologen is used as oxidant, confirming the model of photoinduced reduction and oxidation reactions. The relation of OFF-state lifetimes to redox potentials might enable predictions about the nature of dark states, depending on the fluorophores’ nano-environment in super-resolution microscopy.

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