An efficient dual-channel fluorescence probe for the detection of sulfur dioxide derivatives and viscosity.

In this work, a novel fluorescent probe (CBT) was developed by constructing an efficient fluorescence resonance energy transfer (FRET) and twisted intramolecular charge transfer (TICT) platform to identify SO2 and viscosity changes. CBT has excellent water solubility and exhibits superior fluorescence response performance without the involvement of organic solvents. The energy transfer efficiency (ETE) of CBT is quite high (99.2 %). Besides, CBT not only exhibits high selectivity (fluorescence intensity ratio enhanced 150-fold) and sensitivity (limit of detection: 24 nM) toward SO2 derivatives within 5 min, but also can detect sulfur dioxide derivatives in high-viscosity systems. CBT is highly sensitive to changes in viscosity, showing a significant increase in fluorescence, with the fluorescence intensity increasing by up to 113 times. Furthermore, CBT exhibits low toxicity and good photostability in cells, and can be used to monitor the changes of endogenous and exogenous SO2 derivatives in different living cells.