Molecular engineering-based a dual-responsive fluorescent sensor for sulfur dioxide and nitric oxide detecting in acid rain and its imaging studies in biosystems.

Sulfur dioxide (SO2) and nitric oxide (NO), known as sulfur oxides and nitrogen oxides, are toxic air pollutants and seriously threaten human health. Herein, for the first time, a robust dual-response fluorescent sensor CGT with two different emission fluorophores and dual well-known response-group for visual bisulphites (HSO3-) and nitrites (NO2-) detection was reported. Specifically, once CGT was incubated with HSO3- firstly, the color of the test solution changed to dark yellow with no-fluorescence emission, following added NO2-, the color of the test solution changed to yellow with a bright cyan emission. However, NO2- was added firstly, the color of the test solution changed to dark purple with a white emission, and then added HSO3-, the color of the test solution changed to yellow with a bright cyan emission. Furthermore, CGT showed high sensitivity and selectivity toward HSO3- and NO2- detecting with good detection limits as low as 20.17 nM and 4.14 nM, respectively. Impressively, CGT showed good detection capability in complex aqueous samples and was successfully used for the detection of HSO3- and NO2- in biosystems. Thus, the experimental results indicated CGT as a powerful novel visual detecting tool for HSO3- and NO2- detecting in complex acid rain and biosystems.