An AIE-active fluorescent probe with near-infrared (NIR) emission for selectively monitoring and bioimaging Cys in living cells

Cysteine (Cys), as a kind of essential bio-thiols, plays a pivotal role in modulating cell metabolism, maintaining intracellular redox balance and facilitating protein synthesis. In order to investigate its role in these physiological processes, fluorescent probe was selected as an important method for selectively detecting Cys. However, most of the probes possess ACQ effect, which limits their applications in the field of biosensing and bioimaging. Herein, an AIE-active fluorescent probe TCF-TPA was synthesized for specifically detecting Cys in HeLa cells. TCF-TPA, consisted of a tricyanofuran (TCF) fluorophore, was modified with an acrylate group for distinguish Cys from other bio-thiols, and the incorporation of electron-donating triphenylamine endowed the probe with AIE property and strong intramolecular charge transfer effect, thereby enabling the probe to have near-infrared (NIR) emission length (666 nm). Meanwhile, TCF-TPA possessed low detection limit for Cys (73.0 nM) and was successfully performed bioimaging of Cys in HeLa cells.