Single-molecule characterization of a bright and photostable deep-red fluorescent squaraine-figure-eight (SF8) dye

Kniazev, Kirill; Guo, Tianle; Zhai, Canjia; Gamage, Rananjaya S.; Ghonge, Sushrut; Frantsuzov, Pavel A.; Kuno, Masaru; Smith, Bradley D.

doi:10.1016/j.dyepig.2022.111031

“…[11] However, these methods cannot be used for live cell imaging due to their toxicity. Other strategies for improving organic dyes' single molecule performance include direct conjugation of triplet quencher known as self-healing dyes, [12] and structural modifications such as sulfonation or phosphorylation, [13] modifying steric groups, [14] azetidine ring functionalization, [15] etc. Although these modifications can improve organic dyes' performance, it is still desirable to develop new and straightforward strategies for optimizing probe photostability in SMLM.…”

Section: Introductionmentioning

confidence: 99%

Thiolation for Enhancing Photostability of Fluorophores at the Single‐Molecule Level

Liu,

Zhao,

Zhang

et al. 2023

Angew Chem Int Ed

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Fluorescent probes are essential for single‐molecule imaging. However, their application in biological systems is often limited by the short photobleaching lifetime. To overcome this, we developed a novel thiolation strategy for squaraine dyes. By introducing thiolation of the central cyclobutene of squaraine (thio‐squaraine), we observed a ~5‐fold increase in photobleaching lifetime. Our single‐molecule data analysis attributes this improvement to improved photostability resulting from thiolation. Interestingly, bulk measurements show rapid oxidation of thio‐squaraine to its oxo‐analogue under irradiation, giving the perception of inferior photostability. This discrepancy between bulk and single‐molecule environments can be ascribed to the factors in the latter, including larger intermolecular distances and restricted mobility, which reduce the interactions between a fluorophore and reactive oxygen species produced by other fluorophores, ultimately impacting photobleaching and photoconversion rate. We demonstrate the remarkable performance of thio‐squaraine probes in various imaging buffers, such as glucose oxidase with catalase (GLOX) and GLOX+trolox. We successfully employed these photostable probes for single‐molecule tracking of CD56 membrane protein and monitoring mitochondria movements in live neurons. CD56 tracking revealed distinct motion states and the corresponding protein fractions. This investigation is expected to propel the development of single‐molecule imaging probes, particularly in scenarios where bulk measurements show suboptimal performance.

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An Interlocked Figure‐of‐Eight Molecular Shuttle

Gauthier,

Fournel‐Marotte,

Clavel

et al. 2023

Angewandte Chemie

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Here is reported the synthesis and characterization of an interlocked figure‐of‐eight rotaxane molecular shuttle from a dibenzo‐24‐crown‐8 (DB24C8) derivative. This latter bears two molecular chains, whose extremities are able to react together by click chemistry. One of the two substituting chain holds an ammonium function aimed at driving the self‐entanglement through the complexation of the DB24C8 moiety. In the targeted figure‐of‐eight rotaxane, shuttling of the DB24C8 along the threaded axle from the best ammonium station to the weaker binding site triazolium was performed through deprotonation‐then‐carbamoylation of the ammonium. This way, two discrete co‐conformational states were obtained, in which the folding and size of the two loops could be changed.

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Thiolation for Enhancing Photostability of Fluorophores at the Single‐Molecule Level

Liu,

Zhao,

Zhang

et al. 2023

Angewandte Chemie

0

View full text Add to dashboard Cite

Fluorescent probes are essential for single‐molecule imaging. However, their application in biological systems is often limited by the short photobleaching lifetime. To overcome this, we developed a novel thiolation strategy for squaraine dyes. By introducing thiolation of the central cyclobutene of squaraine (thio‐squaraine), we observed a ~5‐fold increase in photobleaching lifetime. Our single‐molecule data analysis attributes this improvement to improved photostability resulting from thiolation. Interestingly, bulk measurements show rapid oxidation of thio‐squaraine to its oxo‐analogue under irradiation, giving the perception of inferior photostability. This discrepancy between bulk and single‐molecule environments can be ascribed to the factors in the latter, including larger intermolecular distances and restricted mobility, which reduce the interactions between a fluorophore and reactive oxygen species produced by other fluorophores, ultimately impacting photobleaching and photoconversion rate. We demonstrate the remarkable performance of thio‐squaraine probes in various imaging buffers, such as glucose oxidase with catalase (GLOX) and GLOX+trolox. We successfully employed these photostable probes for single‐molecule tracking of CD56 membrane protein and monitoring mitochondria movements in live neurons. CD56 tracking revealed distinct motion states and the corresponding protein fractions. This investigation is expected to propel the development of single‐molecule imaging probes, particularly in scenarios where bulk measurements show suboptimal performance.

show abstract

Single-molecule characterization of a bright and photostable deep-red fluorescent squaraine-figure-eight (SF8) dye

Cited by 5 publications

References 56 publications

Thiolation for Enhancing Photostability of Fluorophores at the Single‐Molecule Level

Thiolation for Enhancing Photostability of Fluorophores at the Single‐Molecule Level

An Interlocked Figure‐of‐Eight Molecular Shuttle

Thiolation for Enhancing Photostability of Fluorophores at the Single‐Molecule Level

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