Defining the Basis of Cyanine Phototruncation Enables a New Approach to Single-Molecule Localization Microscopy

Matikonda, Siddharth S.; Helmerich, Dominic A.; Meub, Mara; Beliu, Gerti; Kollmannsberger, Philip; Greer, Alexander; Sauer, Markus; Schnermann, Martin J.

doi:10.1021/acscentsci.1c00483

Cited by 69 publications

(82 citation statements)

References 46 publications

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“…Since these cyanine dyes are known to suffer from photodegradation, a phenomenon previously detected when they are employed as NIR sensitizers for UCNPs, ,, the photostability of [ L6 Er(hfa) 3 ] + in solution was investigated by recording the changes in the absorption as well as in the upconverted emission spectra with a continuous laser irradiation at a constant excitation power density (5.7 W·cm –2 , Figure S14). As expected, a stepwise decrease in intensity is observed in the dye-centered absorption spectrum (i.e., the NIR part) concomitant with a gradual solution color change from green to orange, while the high-energy absorption bands (the UV part) of the [ L6 Er(hfa) 3 ] + associated with electronic transitions located on the bound multidentate coordinating units remains fairly intact (Figure S14a).…”

Section: Resultsmentioning

confidence: 99%

Ligand-Sensitized Near-Infrared to Visible Linear Light Upconversion in a Discrete Molecular Erbium Complex

et al. 2021

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While the low-absorption cross section of lanthanide-based upconversion systems, in which the trivalent lanthanides (Ln3+) are responsible for converting low- to high-energy photons, has restricted their application to intense incident light, the emergence of a cascade sensitization through an organic dye antenna capable of broadly harvesting near-infrared (NIR) light in upconversion nanoparticles opened new horizons in the field. With the aim of pushing molecular upconversion within the range of practical applications, we show herein how the incorporation of an NIR organic dye antenna into the ligand scaffold of a mononuclear erbium coordination complex boosts the upconversion brightness of the molecule to such an extent that a low-power (0.7 W·cm–2) NIR laser excitation of [L6Er(hfa)3]+ (hfa = hexafluoroacetylacetonate) at 801 nm results in a measurable visible upconverted signal in a dilute solution (5 × 10–4 M) at room temperature. Connecting the NIR dye antenna to the Er3+ activator in a single discrete molecule cures the inherent low-efficient metal-based excited-state absorption mechanism with a powerful indirect sensitization via an energy transfer upconversion, which drastically improves the molecular-based upconverted Er3+-centered visible emission.

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Section: Resultsmentioning

confidence: 99%

Ligand-Sensitized Near-Infrared to Visible Linear Light Upconversion in a Discrete Molecular Erbium Complex

et al. 2021

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“…[ 23 , 24 ] A second, minor photochemical process is a heptamethine truncation reaction that generates small amounts of the pentamethine homologue. [ 25 , 26 ] Quite recently, a third degradation process was elucidated, namely, coupling of two molecules of ICG to give the oxidative dimer 1 . [ 27 , 28 ] However, its prevalence in a stored clinical formulation (2.5 mg/mL in water) was not reported.…”

Section: Introductionmentioning

confidence: 99%

Deuterated Indocyanine Green (ICG) with Extended Aqueous Storage Shelf‐Life: Chemical and Clinical Implications

Smith

2021

Chemistry A European J

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Indocyanine Green (ICG) is a clinically approved near‐infrared fluorescent dye that is used extensively for various imaging and diagnostic procedures. One drawback with ICG is its instability in water, which means that reconstituted clinical doses have to be used very shortly after preparation. Two deuterated versions of ICG were prepared with deuterium atoms on the heptamethine chain, and the spectral, physiochemical, and photostability properties were quantified. A notable mechanistic finding is that self‐aggregation of ICG in water strongly favors dye degradation by a photochemical oxidative dimerization reaction that gives a nonfluorescent product. Storage stability studies showed that replacement of C−H with C−D decreased the dimerization rate constant by a factor of 3.1, and it is likely that many medical and preclinical procedures will benefit from the longer shelf‐lives of these two deuterated ICG dyes. The discovery that ICG self‐aggregation promotes photoinduced electron transfer can be exploited as a new paradigm for next‐generation photodynamic therapies.

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“…An intramolecular pathway is also a possibility (Figure S16b), particularly for the photoconversion of Cy5 singly labeled DNAs that has been performed with an exceedingly low concentration of Cy5. We tested if the enhanced photoconversion of the dual-labeled dT0 relative to the singly labeled DNAs was due primarily to the increased number of sensitizers, which led to a higher local concentration of singlet oxygen that served as the limiting factor of the photoconversion process.…”

Section: Results and Discussionmentioning

confidence: 98%

Mechanism of Cyanine5 to Cyanine3 Photoconversion and Its Application for High-Density Single-Particle Tracking in a Living Cell

Cho

Kim

et al. 2021

J. Am. Chem. Soc.

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Cyanine (Cy) dyes are among the most useful organic fluorophores that have found a wide range of applications in single-molecule and super-resolution imaging as well as in other biophysical studies. However, recent observations that blueshifted derivatives of Cy dyes are formed via photoconversion have raised concerns as to the potential artifacts in multicolor imaging. Here, we report the mechanism for the photoconversion of Cy5 to Cy3 that occurs upon photoexcitation during fluorescent imaging. Our studies show that the formal C 2 H 2 excision from Cy5 occurs mainly through an intermolecular pathway involving a combination of bond cleavage and reconstitution while unambiguously confirming the identity of the fluorescent photoproduct of Cy5 to be Cy3 using various spectroscopic tools. The carbonyl products generated from singlet oxygen-mediated photooxidation of Cy5 undergo a sequence of carbon−carbon bond-breaking and -forming events to bring about the novel dye-to-dye transformation. We also show that the deletion of a two-methine unit from the polymethine chain, which results in the formation of blueshifted products, commonly occurs in other cyanine dyes, such as Alexa Fluor 647 (AF647) and Cyanine5.5. The formation of a blueshifted congener dye can obscure the multicolor fluorescence imaging, leading to misinterpretation of the data. We demonstrate that the potentially deleterious photoconversion, however, can be exploited to develop a new photoactivation method for high-density single-particle tracking in a living cell without using UV illumination and cell-toxic additives.

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Defining the Basis of Cyanine Phototruncation Enables a New Approach to Single-Molecule Localization Microscopy

Cited by 69 publications

References 46 publications

Ligand-Sensitized Near-Infrared to Visible Linear Light Upconversion in a Discrete Molecular Erbium Complex

Ligand-Sensitized Near-Infrared to Visible Linear Light Upconversion in a Discrete Molecular Erbium Complex

Deuterated Indocyanine Green (ICG) with Extended Aqueous Storage Shelf‐Life: Chemical and Clinical Implications

Mechanism of Cyanine5 to Cyanine3 Photoconversion and Its Application for High-Density Single-Particle Tracking in a Living Cell

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