A novel naphthalimide-based fluorescent probe for the colorimetric and ratiometric detection of SO 2 derivatives in biological imaging

SO is a well-known signal molecule and one of reactive sulfur species, which closely participates in many metabolic processes. While unbalanced metabolism of sulfur dioxide can lead to serious complications of various diseases. Therefore, a rapid and accurate monitoring of SO derivatives with high selectivity and sensitivity would be beneficial for their bio-analytic studies. Herein, a novel ratiometric fluorescent probe (NG-TCF) based on ICT mechanism for monitoring SO was developed. The probe underwent a nucleophilic addition of HSO /SO to give rise to a 120 nm blue-shift dual-emission signal changes in enhanced green channel and subdued red channel under a single wavelength excitation. The probe showed fast response rate (within 7 min), good sensitivity (the detection limit is 1.53 µM), and specific response toward HSO /SO over other bio-species, including H S and ClO . Moreover, the probe can be applied for visual ratio imaging of exogenous and endogenous SO derivatives in living cells.