A ratiometric and colorimetric fluorescent probe designed based on FRET for detecting SO₃²⁻/HSO₃⁻ in living cells and mice

Based on the principle of FRET, we have developed a ratiometric and colorimetric fluorescent probe TFBN, which can specifically recognize SO₂ derivatives (SO₃²⁻/HSO₃⁻), and exhibit a transition from red to green fluorescence under 405 nm excitation. The probe TFBN owns the advantages of short response time (<3 min), quantitative detection SO₂ derivatives in two linear ranges, extremely low detection limit (39 nM), large Stokes shift (239 nm) and wide emission window gap (140 nm). In addition, the NBC structure was used as a fluorescent donor for FRET probes for the first time, which expanded the diversity of donors. Importantly, with low toxicity and good biocompatibility, the probe TFBN successfully detects exogenous and endogenous sulfites in living cells. These characteristics endow the probe TFBN can be successfully used in living cells and mouse imaging.