A solvent-assisted ESIPT fluorescent dye was synthesized and used as a probe (2-PPN) for the detection of F-/Ag+ and high-resolution imaging of the cilia in live cells. The developed ESIPT fluorophore exhibited strong tautomeric fluorescence in protic solvents and normal emission in aprotic solvents, which is a significant departure from that of conventional intramolecular ESIPT compounds. The H-binding interaction of F- and the chelation of Ag+ with the ESIPT module of 2-PPN resulted in significant tautomeric emission quenching. From this basis, the 2-PPN-based assays for the detection of F- and Ag+ were established. The detection limit for F- and Ag+ sensing is 2.4 nM and 1.5 nM, respectively. The selective experimental results showed that no tautomeric fluorescence change of 2-PPN could be observed in the presence of the other inorganic ions in the same medium, revealing high selectivity of 2-PPN to F- and Ag+. Furthermore, MTT assay experiments proved that the probe 2-PPN exhibited low cytotoxicity and good cell membrane permeability. The probe was also further successfully utilized to image the cilia in vitro MCF7 cells, displaying its high-resolution imaging performance.Graphical abstract.
Keywords: F−/Ag+ sensing; MCF7 cells; Solvent-assisted ESIPT fluorescent dyes; Subcellular organelle imaging.
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