All-in-one: Accurate quantification, on-site detection, and bioimaging of sulfite using a colorimetric and ratiometric fluorescent probe in vitro and in vivo.

SO and its derivatives (SO/HSO) are used widely in food, beverages, and pharmaceutical production. However, they could induce multiple diseases in respiratory, nervous, and cardiovascular systems. Although several fluorescent probes have been developed for detecting SO/HSO, reports on rapid fluorescent probes for the on-site detection of SO derivatives are scarce. Herein, a colorimetric and ratiometric fluorescent probe 1 based on the intramolecular charge transfer (ICT) was reported. Probe 1 resulted in a 122 nm blue-shift in fluorescent emission and decrement of absorbance at 500 nm upon the addition of sulfite. Therefore, probe 1 could quantify SO/HSO using both UV-Vis and fluorescent methods (LOD: UV-Vis method 34 nM; fluorescent method 51 nM). Importantly, probe 1 was used for a rapid (60 s) and convenient (1 step, on-site) measurement of the SO derivatives in real samples (LOD: 0.47 µM) using smartphone based on the colorimetric method. The SO/HSO-sensing mechanism was confirmed as the Michael addition reaction. Furthermore, the probe was used for the real-time monitoring of SO/HSO in A549 cells and zebrafish. In summary, an all-in-one fluorescent probe was successfully developed for the accurate quantification, on-site detection, and bioimaging of SO/HSO.