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Spectrophotometric Determination of Glutathione and Cysteine Based on Aggregation of Colloidal Gold Nanoparticles

Seyyed Hosseini, Ensieh | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41985 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Hormozi Nezhad, Mohammad Reza
  7. Abstract:
  8. low-molecular-weigth aminothiols such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) play a critical role in many biochemical pathways . Their level in biological fluids such as human plasma and urine are important for clinical diagnostics of a variety of diseases.
    We report herein the development of a highly sensitive colorimetric method for detection of cysteine and glutathione using the citrate capped gold nanoparticles (Au-NPs). This thiol containing molecules exhibit intriguing reactivities with Au nanoparticles. The reactivity involves the displacement of the citrate shell by the thiolate shell which is followed by intermolecular electrostatic interactions or hydrogen-bonding between the thiolate shells. The interparticle interactions depends on the ionic strength, pH and Au-NPs concentration of the solution. The interparticle interactions lead to a decrease in the plasmon band at around 521nm and the formation of a new red shifted band . The calibration curve drived from the ratio intensities of absorbance at-640 nm and 650nm for cysteine and glutathione respectively to original wavelength (521 nm). It was linear in the concentration range of 1 × 10-6 – 100 × 10-6 M for cysteine and 5 × 10-6 – 200 × 10-6 M for glutathione. The detection limit (3σ) for cysteine was 2.1× 10-6 M and for glutathione was 3.3 × 10-6 M
  9. Keywords:
  10. Gold Nanoparticle ; Cysteine ; Association ; Spectrophotometric ; Glutathione

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