Phenoxazine-based Near-infrared Fluorescent Probes for the Specific Detection of Copper (II) Ions in Living Cells

: It is well known that copper ions play a critical role in various physiological processes. However, a variety of human diseases are tightly correlated with copper overload. Although there are numerous fluorescent probes capable of detecting copper ions, most of them are turn-off probes owing to copper (II) ions fluorescence quenching effect, resulting in poor sensitivity. Herein, a novel turn-on near-infrared (NIR) fluorescent probePZ-Nbased on phenoxazine was designed and synthesized for the selective detection of copper (II) ions (Cu2+). Upon the addition of Cu2+, the probe could quickly react with Cu(2+)and emit strong fluorescence, along with colour change from colourless to obvious blue. Moreover, the probePZ-Nshowed good water solubility, high selectivity, and excellent sensitivity with low limit of detection (1.93 nM) towards copper (II) ions. More importantly,PZ-Nwas capable of effectively detecting Cu(2+)in living cells.