Phenazine-Based Fluorescence”Turn-Off”Sensor for Fluoride: Application on Real Samples and to Cell and Zebrafish Imaging

摘要

In the present work,we report the design of a novel chemosensor 2-(1H-indole-3-yl)-1H-imidazo[4,5-b]phenazine,(R)for fluoride ion detection via a naked eye observable colour change from light yellow to brown along with 10 fold ratiometric fluorescence quenching from green to no fluorescence in a matrix containing a large number of similar toxic anions in aqueous dimethylsulfoxide(30% H2O + DMSO)solution.The sensing mechanism was ascertained to be the fluoride triggered deprotonation of imidazole as well as indole moiety of R which is supported by 1:2 saturation level equivalence of R-F-.R was fully characterized through FT-IR,1H,~(13)C NMR and HRMS.R is an effective receptor for F-within a wide range of pH that indicates its bio-compatibility.LoD and Ka for F~-were found to be 1.8×10-6 M(below 0.34 mg/Liter)and 2.7 × 10~4 M~(-1)respectively.The experimental observations were supported by the theoretical calculations using density functional theory.R also showed its potential practical applicability for fluoride detection in toothpaste solution.Furthermore,to prove its nontoxicity,probe R also applied to a cytotoxicity assay of HeLa cells followed by confocal fluorescence cells imaging and Zebrafish imaging experiments.