Modified Isoindolediones as Bright Fluorescent Probes for Cell and Tissue Imaging |
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Authors: | Dr Olena Vakuliuk Dr Yong Woong Jun Kateryna Vygranenko Guillaume Clermont Ye Jin Reo Dr Mireille Blanchard-Desce Prof Kyo Han Ahn Prof Dr Daniel T Gryko |
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Institution: | 1. Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland;2. Department of Chemistry, POSTECH, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyungbuk, 37673 Korea;3. Univ. Bordeaux, ISM (UMR5255 CNRS), 33400 Bordeaux, France |
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Abstract: | New L -shaped fluorophores possessing five conjugated rings have been synthesized through a four-step procedure involving diketopyrrolopyrrole synthesis and its double N-alkylation, followed by trimethylsilyl bromide-mediated rearrangement to thieno2,3-f]isoindole-5,8-dione and an intramolecular Friedel–Crafts reaction. In comparison with the parent isoindolediones and π-expanded diketopyrrolopyrroles, these new dyes show red-shifted absorption and emission (up to ≈630 nm). Their structural rigidity is responsible for both the observed small Stokes shifts and large fluorescence quantum yields. Tissue imaging studies revealed that these new dyes show advantageous features including minimal autofluorescence interference and pronounced solvent-sensitive emission. Interestingly, there is a fundamental difference between a dye possessing an amino group and its analog bearing an N-alkyl substituent. The former dye under two-photon excitation at 900 nm gives bright images whereas its N-alkylated counterpart does not. A new type of membrane localization has been discovered by an N-alkylated isoindoledione possessing a benzofuryl substituent. In spite of the fact that the fluorescence quantum yield of this dye in a range of solvents is rather low, it does stain cell membranes exclusively. This new mode of cellular staining opens the door towards further development of membrane staining dyes. |
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Keywords: | diketopyrrolopyrrole donor-acceptor systems dyes/pigments fluorescence fluorescent probes |
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