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Simultaneous Determination of Glutathione- Cysteine, and Detection of Mercury Ion (II) Based on Fluorescence Resonance Energy Transfer between Gold Nanoparticles and Fluorescein Isothiocyanate

Mohammadi, Jamaloddin | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47257 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Hormozi-Nezhad, Mohammad Reza
  7. Abstract:
  8. Turn-On Fluorescence detection is a selective and sensitive method for many analytical purposes. Fluorescence quenching is a commonly observed consequence when fluorophores and quencher, gold nanoparticles (Au NPs) in this work, are in same media. Here, we report a “turn-on” fluorescent nanoprobe for simultaneous determination of glutathione and cysteine using H-point standard addition method (HPSAM). This probe develops based on the fluorescence resonance energy transfer (FRET) between Au NPs and fluorescein isothiocyanate (FITC), in which FITC acts as the donor and Au NPs as the acceptor. FRET causes the fluorescence intensity of FITC strictly quenched as a result of noncovalently adsorbed on Au NPs surface. This probe operated on a basic principle that glutathione and cysteine have stronger affinity to Au NPs, so deposit on the surfaces of the Au NPs and induce the release of FITC molecules into the solution with different rates, and thus restored the florescence signal of FITC. The H-point standard addition method (HPSAM) was applied to kinetic data for simultaneous determination of glutathione and cysteine. Under the optimum conditions (i.e. pH=8.5, CAuNPs=1.08 nM), the fluorescence intensity of the released FITC displays a linear relationship in the range of 1.0×10-7 to 3.0×10-7 M of Glutathione in the presence of cysteine. The proposed method was successfully applied to the determination of glutathione in the presence of different concentration of cysteine in several synthetic mixtures. In the second work, we determine mercury ion (II) with the inhibition of turn-on fluorescence method which is mentioned in first paragraph. This route is based on formation of a stable complex between mercury ion and cysteine; and we used FITC modified Au NPs as a probe for cysteine molecule. Under the optimum conditions, the fluorescence intensity of the released FITC displays a linear relationship in the range of 2.5×10-8 M to 7.0×10-7 M of mercury ion (II). Lower limit of detection for mercury ion (II) was 2.4×10-8 M. The proposed method was successfully applied to the determination of mercury ion (II) in the several water samples
  9. Keywords:
  10. Gold Nanoparticle ; Glutathione ; Cysteine ; Fluorescence Resonance Energy Transfer ; Fluorescence Isothiocyanate ; H-Point Standard Addition Method

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