A novel "AIE plus ESIPT" mechanism-based fluorescent probe for visual alternating recognition of HSO3- /H2O2 and its HSO3- detection in food samples

Maintaining redox homeostasis in organisms plays a crucial role in human life and health, and changes in the levels of SO2 and H2O2, as typical representative substances of reductants and oxidants, directly affects intra-cellular redox homeostasis. Hence, it is necessary to manufacture fluorescent probes that can detect HSO3- and H2O2. In this work, a benzopyrylium salt containing benzothiazole derived fluorescent probe HBTO-H with dual properties of aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) has been developed. The probe displays rapid and reversible test of HSO3- and H2O2 in DMF/Tris (v:v = 2:8, pH = 7.3, Tris 10 mM) mixed solvent with high selectivity, good anti-interference ability and a wide applicable pH range (6-11). The detection limits of HBTO-H for HSO3- and H2O2 are 0.187 mu M and 0.152 mu M, respectively. The response mechanisms of HBTO-H toward HSO3-; and H2O2 have been demonstrated to be Michael addition re-action and its retro-reaction based on H-1 NMR and HRMS analyses. In addition, HBTO-H has been successfully applied to check HSO3- in sugar and wine specimens. Moreover, HBTO-H was proved to be mitochondria-targetable and can alternately detect exogenous HSO3- and H2O2 in MCF-7 cells, which is desired to be applied to trace HSO3- in organisms in the future.