Ultrafast Detection of Sulfur Dioxide Derivatives by a Distinctive "Dual-Positive-Ion" Platform that Features a Doubly Activated but Irreversible Michael Addition Site

Sulfur dioxide (SO2) is a gaseous signaling molecule and widely used as a preservative for foods, but its excessive intake is closely related to a series of diseases. Therefore, the development of a potent fluorescence probe for the detection of SO2 in foods and biological systems is of great significance. Herein, we report for the first time a "dual-positive-ion" platform-based fluorescence probe CMQ, designed by a doubly activated but irreversible strategy, which results in its ultrafast response to SO2 within 5 s in pure aqueous solution together with a low detection limit as 15.6 nM. In addition, the probe was successfully applied for imaging of SO2 in mitochondria of living cells and zebrafish and prepared as a reagent kit for convenient and instantaneous quantification of HSO3- in real food samples.