8-Hydroxyquinoline functionalized ZnS nanoparticles capped with amine groups: A fluorescent nanosensor for the facile and sensitive detection of TNT through fluorescence resonance energy transfer

8-Hydroxyquinolines (HQs) functionalized ZnS nanoparticles (NPs) with an amine-capping layer (ZnS–NH2–Q NPs) were prepared by a ligand-exchange process. FT-IR, XRD, NMR, TEM and fluorescence spectrometer were used to characterize the novel ZnS–NH2–Q NPs. Upon the addition of 2,4,6-trinitrotoluene (TNT), the amino groups on the surface of ZnS–NH2–Q NPs can bind TNT molecule from solution by forming Meisenheimer complex. This complex absorbs the green part of visible light, and strongly suppresses the fluorescence emission of the ZnS–NH2–Q NPs through Fluorescence Resonance Energy Transfer (FRET). The observed linear fluorescence intensity response for TNT in the range of 0–1.89 μM allows the quantitative detection TNT, with a detection limit down to 10 nM.

Graphical abstract2-mercaptoethanol (ME) and 2-mercaptoethylamine (MEA) as coligands were used to stabilize the ZnS NPs. 8-Hydroxyquinolines (HQ) were anchored to the surface of NPs to form ZnS–NH2–Q NPs. This novel surface-functionalized NPs can provide a facile strategy to detect 2,4,6-trinitrotoluene (TNT) in solution through Fluorescence Resonance Energy Transfer (FRET). A linear fluorescence intensity response for TNT in the range of 0–1.89 μM allows the quantitative detection TNT, with a detection limit down to 10 nM.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Organic amine capped fluorescent ZnS NPs were functionalized with 8-hydroxyquinoline. ► The PL quenching of ZnS–NH2–Q NPs is sensitive to the content of TNT due to FRET. ► The PL sensor allows a quantitative detection TNT with a detection limit of 10 nM. ► Our strategy opens up a new perspective in the design of sensor for various analytes.