Green fluorescent carbon dots from chitosan as selective and sensitive off-on probes for nitrite and on-off-on probes for enrofloxacin detection

In this work, green emission fluorescence carbon dots (G-CDs) were prepared using chitosan and p-phenylenediamine as precursors. Furthermore, the fluorescence of the prepared G-CDs was quenched by Nitrite (NO2-) with excellent selectivity and sensitivity due to internal filtration effect (IFE) Therefore, G-CDs was applied to monitor NO2- as an on-off fluorescence probe and obtained a wide linear range (1-300 mu M) with limit of detection (LOD) 1.00 mu M. Another hand, the fluorescence of G-CDs was also quenched by Au3+ due to fluorescence resonance energy transfer (FRET) effect caused by the in-situ formed Au nanoparticles (AuNPs). Interestingly, the addition of enrofloxacin (Enr) to G-CDs/AuNPs system led to the aggregation of AuNPs with partly lager size G-CDs, and the quenched fluorescence of the G-CDs/AuNPs system was restored, accompanying with visible fluorescence color change from green to blue. The on-off-on detection method through the constructed G-CDs/AuNPs system to Enr obtained good effects, such as high selectivity, sensitivity, visibility, relatively wide linear range (1-50 mg/L) and low LOD (0.04 mg/L). Additionally, the prepared G-CDs could be used for the detection of NO2- and Enr in actual water samples, proving it is an excellent candidate for environmental detection of NO2- and Enr. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, green emission fluorescence carbon dots (G-CDs) were prepared using chitosan and p-phenylenediamine as precursors. The prepared G-CDs showed selective and sensitive quenching of fluorescence by Nitrite (NO2-) due to internal filtration effect (IFE). Additionally, the fluorescence of G-CDs was quenched by Au3+ through fluorescence resonance energy transfer (FRET) effect caused by in-situ formed Au nanoparticles (AuNPs). The G-CDs/AuNPs system showed on-off and on detection of enrofloxacin (Enr) with good selectivity, sensitivity, visibility, wide linear range, and low limit of detection.