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Fluorogenic Squaraine Dendrimers for Background‐Free Imaging of Integrin Receptors in Cancer Cells
Author(s) -
Ashokkumar Pichandi,
Collot Mayeul,
Klymchenko Andrey S.
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202100480
Subject(s) - dendrimer , fluorescence , quantum yield , linker , chemistry , biophysics , photochemistry , rational design , conjugate , intramolecular force , quenching (fluorescence) , histone octamer , molecule , combinatorial chemistry , nanotechnology , materials science , stereochemistry , polymer chemistry , organic chemistry , biochemistry , optics , dna , mathematical analysis , physics , mathematics , nucleosome , computer science , biology , histone , operating system
To overcome the limited brightness of existing fluorogenic molecular probes for biomolecular targets, we introduce a concept of fluorogenic dendrimer probe, which undergoes polarity‐dependent switching due to intramolecular aggregation‐caused quenching of its fluorophores. Based on a rational design of dendrimers with four and eight squaraine dyes, we found that octamer bearing dyes through a sufficiently long PEG(8) linker displays >400‐fold fluorescence enhancement from water to non‐polar dioxane. High extinction coefficient (≈2,300,000 m −1 cm −1 ) resulted from eight squaraine dyes and quantum yield (≈25 %) make this octamer the brightest environment‐sensitive fluorogenic molecule reported to date. Its conjugate with cyclic RGD used at low concentration (3 n m ) enables integrin‐specific fluorescence imaging of cancer cells with high signal‐to‐background ratio. The developed dendrimer probe is a “golden middle” between molecular probes and nanoparticles, combining small size, turn‐on response and high brightness, important for bioimaging.