Construction of a novel near-infrared fluorescent probe with multiple fluorescence emission and its application for SO derivative detection in cells and living zebrafish.

Sulfur dioxide (SO) in biological systems is an important gaseous signal molecule and plays important roles in physiological activities. It can be endogenously produced by enzymes in mitochondria during oxidation of sulphur-containing molecules. Thus, the development of probes for sulfur dioxide detection in biological environment is necessary. Here, a new near-infrared fluorescent probe (Rh-TPA) with multiple fluorescence emission was constructed and applied for SO derivative detection. Rh-TPA was constructed via conjugation of a rhodamine analogue with a triphenylamine group. Rh-TPA exhibited a major emission peak at 740 nm and a shoulder peak at 810 nm. After interacting with SO derivatives, the conjugated system dissociated into two smaller chromophores with two emission peaks (520 nm and 570 nm) in the visible region. The probe showed negligible cytotoxicity, as demonstrated by the MTT results. Biological imaging application experiments indicated that the probe can be used to image SO derivatives in HeLa cells and living zebrafish.