Mitochondria-targeted fluorescent probes based on the FRET principle for the detection of sulfite

Sulfur dioxide and its derivatives have garnered significant attention in the fields of environmental pollution, life sciences, and health. In this study, a series of fluorescent probes (NPB1 ∼ 9) were designed and synthesized. These probes were used for the rapid identification of SO₃^2-. During the reaction process, the red fluorescence changed to blue/green fluorescence, featuring high selectivity, short response time, wide pH adaptability range, and detection limits of 30 nM. The identification mechanism involves a CC addition reaction within the receptor, which alters the intramolecular charge transfer and fluorescence resonance energy transfer effects, resulting in a fluorescence color switch. It has also been successfully applied to the detection of SO₃^2- in various food and water samples, with a recovery rate of 95-115 %. Importantly, NPB6 has low cytotoxicity, good mitochondrial targeting ability, and has been successfully used for the visual fluorescence imaging of endogenous and exogenous SO₃^2- in living cells.