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 (SO ₂ ) 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 (HSO ₃ ^- ) and nitrites (NO ₂ ^- ) detection was reported. Specifically, once CGT was incubated with HSO ₃ ^- firstly, the color of the test solution changed to dark yellow with no-fluorescence emission, following added NO ₂ ^- , the color of the test solution changed to yellow with a bright cyan emission. However, NO ₂ ^- was added firstly, the color of the test solution changed to dark purple with a white emission, and then added HSO ₃ ^- , the color of the test solution changed to yellow with a bright cyan emission. Furthermore, CGT showed high sensitivity and selectivity toward HSO ₃ ^- and NO ₂ ^- 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 HSO ₃ ^- and NO ₂ ^- in biosystems. Thus, the experimental results indicated CGT as a powerful novel visual detecting tool for HSO ₃ ^- and NO ₂ ^- detecting in complex acid rain and biosystems.
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