A dual functional probe: sensitive fluorescence response to H2S and colorimetric detection for SO32-

Hydrogen sulfide (H2S) and sulfite (SO32-) are two important sulfur-containing species that play different and important roles in industrial and biological processes. Accordingly, the development of efficient methods for simple, rapid, sensitive and selective monitoring of H2S and SO32- is of the utmost importance in both environmental and biological sciences. In this study, we developed a new dual functional probe NIR-DNP for discriminative detection of H2S and SO32-. This probe can sense H2S and SO32- via two different approaches, a significant near-infrared fluorescence enhancement and color change from purple to cyan induced by H2S as well as a visible color change from purple to colorless caused by SO32-. The detection limits of the probe NIR-DNP for H2S and SO32- in aqueous solutions were 36.53 nM and 33.33 nM, respectively. Competitive experiments demonstrated that the probe NIR-DNP had a high fluorescence selectivity for H2S and excellent colorimetric selectivity for SO32- over other analytes. The sensing mechanism of the probe toward H2S and SO32- was based on the H2S-induced thiolysis of dinitrophenyl ether and SO32- induced nucleophilic addition, respectively. Further investigation showed that the probe NIR-DNP could be used to develop an easy-to-prepare and easy-to-detect paper-based test strip for cheap and effective detection of SO32-. Also, the probe NIR-DNP has the potential to image exogenous and endogenous H2S in living cells.