Results
Title

Fluorogenic Squaraine Dendrimers for Background‐Free Imaging of Integrin Receptors in Cancer Cells.

Authors

Ashokkumar, Pichandi; Collot, Mayeul; Klymchenko, Andrey S.

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.

Subjects

CELL receptors; DENDRIMERS; INTEGRINS; CANCER cells; CELL imaging; POLYAMIDOAMINE dendrimers; MOLECULAR probes; FLUOROPOLYMERS

Publication

Chemistry - A European Journal, 2021, Vol 27, Issue 22, p6795

ISSN

0947-6539

Publication type

Academic Journal

DOI

10.1002/chem.202100480