Fluorogenic Squaraine Dendrimers for Background‐Free Imaging of Integrin Receptors in Cancer Cells. Issue 22 (16th March 2021)

• Record Type: Journal Article
• Authors: Ashokkumar, Pichandi; Collot, Mayeul; Klymchenko, Andrey S.
• Is Part Of: Chemistry. Volume 27:Issue 22(2021)
• Page Start: 6795
• Page End: 6803
• Publication Date: 2021-03-16
• Subjects: aggregation -- dendrimers -- fluorescent probes -- fluorogenic response -- integrin receptor; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202100480
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: 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 nm ) 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. Abstract : Fluorogenic dendrimer probe for imaging membrane receptors has been developed. It combines eight squaraine dyes that undergo polarity‐dependent aggregation–disaggregation within the dendrimer, resulting in OFF–ON fluorescence response to a biomolecular target. It enables integrin‐specific imaging of cancer cells with high signal‐to‐background ratio.