Invited feature articleCoumarin-naphthol conjugated Schiff base as a “turn-on” fluorescent probe for Cu2+ via selective hydrolysis of imine and its application in live cell imaging

•A coumarin-naphthol conjugated Schiff base for detecting Cu2+ was developed.•The sensing mechanism was illustrated to be Cu2+ promoting the imine hydrolysis.•The probe exhibited high sensitivity and low detection limit (12.7 nM).•The practical application in bio-imaging study was successfully achieved.

An off-on fluorescent probe (CuCIN), coumarin-naphthol linked by an imine group, for detecting Cu2+ in DMSO-HEPES buffer (1:99, v/v) solution was successfully developed. Mechanism studies suggested that CuCIN firstly formed a complex with Cu2+ in a 1:2 metal-to-ligand ratio, and then 60-fold fluorescence enhancement was observed when Cu2+ promoted the imine hydrolysis to release the fluorescence compound 7-diethylaminocoumarin-3-aldehyde. This probe displayed desired properties such as high selectivity toward other metal ions, low detection limit (12.7 nM) and low cytotoxicity. Bio-imaging study revealed that the new probe CuCIN could be applied for imaging living cells with good cell permeability. We hope to apply this probe in the biomedical research field for the imaging of disease-relevant Cu2+.

Graphical abstractA coumarin-naphthol conjugated Schiff base was synthesized as a “turn-on” fluorescent probe (CuCIN) for highly selectivity detection of Cu2+ and bio-imaging.Download high-res image (100KB)Download full-size image