A highly selective and sensitive flavonoid fluorescent probe for the detection of Al3+ in aqueous environments and its application in cellular imaging

Abstract

Abstract Aluminum (Al), which is not an essential element in maintaining the living system could cause chronic toxicity. The specific and sensitive detection of Al3+ is a prerequisite to evaluating its risk to life. We rationally designed and synthesized a novel bromoflavonol-based fluorescent probe IV, which shows a blue shift of the emission and fluorescence enhancement after binding to Al3+, and thus could be used for Al3+ detection. UV-Vis absorption and fluorescence emission spectra show that Ⅳ has high selectivity and sensitivity to Al3+ and exhibits strong immunity to other metal ions. The detection limit(LODs) of Ⅳ to Al3+ is 1.8×10− 8 mol/L as deduced from the fluorescence titration. The binding stoichiometry of Ⅳ to Al3+ is 1:1 as deduced from Job curve and 1H NMR titration. The HOMO and LUMO energy gap difference between Ⅳ and Ⅳ་Al3+ was calculated by DFT (generalized functional theory), and the structure of the complex formed with probe IV and Al3+ is more stable than that of IV. Al3+ was detected in tap water and river water in the middle regions of the Han River with recoveries of more than 96% by using this probe, which can realize the quantitative detection of Al3+ in environmental water samples. In addition, the probe can be successfully used for imaging of Al3+ in the MG63 cells, indicating a potential application of this fluorescence probe in biological imaging.