A rationally designed fluorescent probe for sulfur dioxide and its derivatives: applications in food analysis and...

Exogenous sulfur dioxide (SO₂) and its derivatives (SO₃^2-/HSO₃^-) have been extensively utilized in food preservation and endogenous SO₂ is recognized as a significant gaseous signaling molecule that can mediate various physiological processes. Overproduction and/or extensive intake of these species can trigger allergic reactions and even tissue damage. Therefore, it is highly desirable to monitor SO₂ and its derivatives effectively and quantitatively both in vitro and in vivo. Herein, a new mitochondria-targeted fluorescent probe (PIB) had been constructed, which could ratiometrically recognize SO₂ and its derivatives with excellent sensitivity (DL = 15.9 nM) and a fast response time (200 s). The obtained high selectivity and good adaptability of this SO₂-specific probe in a wide pH range (6.5-10.0) allowed for quantitatively tracking of SO₂ and its derivatives in real food samples (granulated sugar, crystal sugar, and white wine). In addition, PIB could locate at mitochondrion and was capable of imaging exogenous/endogenous SO₂ in the cells and zebrafish. In particular, our findings represented one of the rare examples that have demonstrated endogenous SO₂ is closely related with the apoptosis of cells. Importantly, probe PIB was successfully employed for in situ metabolic localization in mouse organs, implying the potential applications of our probe in further exploration on SO₂-releated pathological and physiological processes.