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

合成了溶剂辅助 ESIPT 荧光染料并用作探针 (2-PPN)，用于检测 F ^- /Ag ⁺和活细胞纤毛的高分辨率成像。开发的 ESIPT 荧光团在质子溶剂中表现出强烈的互变异构荧光，在非质子溶剂中表现出正常发射，这与传统的分子内 ESIPT 化合物有很大的不同。^{F -}的 H 结合相互作用和 Ag ⁺与 2-PPN 的 ESIPT 模块的螯合导致显着的互变异构发射猝灭。在此基础上，建立了基于 2-PPN 的 F ^-和 Ag ⁺检测方法。F ^-和 Ag的检测限⁺感应分别为 2.4 nM 和 1.5 nM。选择性实验结果表明，在相同介质中存在其他无机离子的情况下，2-PPN没有发生互变荧光变化，表明2-PPN对F ^-和Ag ⁺具有较高的选择性。此外，MTT测定实验证明探针2-PPN具有低细胞毒性和良好的细胞膜通透性。该探针还成功地用于体外MCF7细胞纤毛成像，显示出其高分辨率成像性能。

图形概要