A Kumujian-C based highly selective fluorescence turn-on probe enables the detection of sulfite in real samples and living cells.

Highly sensitive and easy to use sensors are required to measure in vitro and in vivo sulfite ion concentrations for better human health. To date various fluorescence-based probes have been utilized for sulfite detection, but most of them suffer from cumbersome synthetic protocols and lengthy detection times, which somewhat limit their widespread applications. Herein, we have developed a highly selective and fast responsive fluorescent probe, Kumujian-C (Kum-C) for the detection of sulfite ions in both in vitro and in vivo conditions. Kum-C, a β-carboline-based small molecule fluorescent probe, was synthesised and its photophysical properties in different conditions were evaluated. The aqueous solution of the probe was weakly fluorescent, but upon selective binding with sulfite ions, the probe instantly displayed a phenomenal enhancement in its fluorescence intensity. This turn-on response was found to be linear over the range of 0 to 125 μM sulfite concentration, enabling the probe to detect sulfite down to 0.35 μM in buffer. Moreover, high selectivity, and fast response toward sulfite ions over other anions and bio-analytes, established the developed probe as an efficient sulfite sensor. Finally, using the probe, the detection of sulfite ions in real food samples as well as in living cells has also been demonstrated. [ABSTRACT FROM AUTHOR]