Chemistry
GAO Wei, YIN Kaiyue, WANG Zejin, WANG Qingming, SU Jing, HOU Xiaojia, YUAN Caixia
To enhance the sensitivity of fluorescence probes for the detection of Zn2+, this study introduces an OFF-ON Zn2+ detection strategy. This approach utilizes a dual quenching mechanism involving fluorescein ring closure-opening and (E)-4-((4-(dimethylamino) phenyl) diazenyl) benzoic acid (DABCYL) as a dual quencher. The primary objective is to address the issue of high background fluorescence associated with bis (pyridin-2-ylmethyl) amine (DPA) based Zn2+ recognition groups in various fluorescence probes. The Zn2+ fluorescence probe 4',5'-bis((bis(pyridin-2-ylmethyl)amino)methyl)-2', 7'-dichloro-3'-hydroxy-3-oxo-3H-spiro [isobenzofuran-1,9'-xanthen]-6'-yl (E)-4-((4-(dimethylamino) phenyl) diazenyl) benzoate (FL-ZJ) was synthesized using a fluorescein precursor molecule, with DPA serving as the recognition group and DABCYL functioning as the dual quencher. The fluorescence response of FL-ZJ to Zn2+ was investigated through fluorescence spectroscopy. Results indicated that FL-ZJ exhibited minimal fluorescence activity at 526 nm in the absence of Zn2+. Upon introduction of Zn2+, the fluorescence intensity at 526 nm increased to approximately 17.4-fold, accompanied by a color change from colorless to yellow. The detection limit for Zn2+ using this probe was determined to be 14.6 nmol/L. Further analysis via Job's Plot experiments and high-performance liquid chromatography revealed that coordination-induced ring opening of the fluorescein moiety and intramolecular elimination of the quenching group facilitated the selective detection of Zn2+.