One-step Hydrothermal Synthesis Of WS₂ Quantum Dots For Selectivity Detection Of Fe³⁺,Hemoglobin And Myoglobin

Tungsten disulfide（WS₂）is one of transition metal dichalcogenides（TMDs）with graphene-analogous structure.When the size is controlled to be less than 10 nm,zero-dimensional WS₂ quantum dots（WS₂ QDs）can be obtained.Because of quantum confinement and edge effects,WS₂ QDs possess unique optical and electronic properties and are potentially applied in fluorescent sensing,biomedicine and hydrogen evolution reaction,etc.In this thesis,WS₂ QDs were synthesized via a facile one-step hydrothermal method.We explored the fluorescence properties and morphologies of the obtained WS₂ QDs.The applications of the WS₂ QDs as fluorencent probe were also investigated.This dissertation includes the following aspects:1.Synthesis and characterization of WS₂ QDsWS₂ QDs were synthesized using sodium tungstate and glutathione as precursors by one-step hydrothermal method after optimizing various conditions.The morphology and optical properties of WS₂QDs were characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,atomic force microscopy（AFM）,energy dispersive spectrometer（EDS）,fourier transform infrared（FTIR）spectroscopy,fluorescence（FL）spectroscopy and UV-vis spectroscopy,etc.The results showed that the as-prepared WS₂QDs possessed excellent photoluminescent features with narrow size distribution and good water solubility.The average size of WS₂QDs is 1.9 nm with 0.95 nm of thickness.The quantum efficiency of WS₂QDs was 11.23%.2.WS₂ QDs for fluorescence“turn off-on”detection of Fe³⁺and ascorbic acid（AA）We found that most amino acids had no obvious effects on the luminescence of WS₂QDs,but WS₂QDs could be selectively quenched by Fe³⁺through photoinduced electron transfer（PET）effect.In the presence of AA,the fluorescence quenched by Fe³⁺could be recovered,which indicated that WS₂QDs could be used as an“turn off-on”probe for Fe³⁺and AA.A wide linear range for Fe³⁺was acquired from 0.2μM to 1400μM with a detection limit of 0.071μM.Meanwhile,a linear range from 0.1-400μM with a detection limit of 0.042μM for AA was presented.The content of AA in real samples was then detected with satisfactory results.3、The applications of WS₂QDs in the assay of the hemoglobin（Hb）and myoglobin（Myo）levels in human bloodBased on the phenomenon of WS₂ QDs quenched by Fe³⁺,the interaction between hemoglobin/myoglobin and WS₂QDs were also explored.The fluorescence quenching of WS₂QDs was very sensitive to Hb and Myo.There is a good linear relationship between（F₀-F）/F₀（where F₀ and F are the fluorescence intensity of the WS₂QDs before and after interaction with Hb/Myo）and protein concentration.The detection limit of 0.26μg/m L and0.0076μg/m L for hemoglobin and myoglobin was obtained,respectively.The method was successfully used for the determination of hemoglobin and myoglobin in human blood samples.It replies that WS₂QDs could be applied in the clinical examinations and biochemical analysis.