Fluorescent chitosan hydrogel for highly and selectively sensing of p-nitrophenol and 2, 4, 6-trinitrophenol.

• Fluorescence functionalization of chitosans is achieved, and they are sensitive and selective to TNP and 4-NP. • The macromolecular sensors remain the sensitivity of small molecular sensors, enve improve sensitivity. • Some of the fluorescent chitosan remain the gel performance as the original chitosan. Nitroaromatic compounds, especially 2, 4, 6-trinitrophenol, have strong biological toxicity and explosive risks, so the detection of 2, 4, 6-trinitrophenol exhibit importantly practical and scientific significance. In this work, three fluorescence functionalized chitosan CNS 3 , CNS 4 and CNS 5 were prepared using chitosan as matrix. When 2, 4, 6-trinitrophenol (TNP) and/or p-nitrophenol (4-NP) was present in spot, these fluorescent chitosan sensors produced notable fluorescence quenching. It renders the chitosan sensing ability to detect TNP and 4-NP selectively and sensitively. The sensing mechanism is investigated as well. When introduced electron-rich moieties to the fluorescent chitosan, the sensitive detecting ability could be obtained. Excellent recognition ability could reach as low as 0.28 μM. The fluorescence fictionalization cause slight influence to the gel performance of chitosan. [ABSTRACT FROM AUTHOR]