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Colorimetric Sensing of Nitrite and Glutathione Based on Morphological Changes of High Aspect Ratio of Gold Nanorods

Fahimi - Kashani, Nafiseh | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44807 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Hormozi Nezhad, Mohammad Reza
  7. Abstract:
  8. The fascinating size-dependent properties of noble metal nanop articles have created a great promise for their use in a different applications specially chemical sensing. Gold nanorods (GNRs), specifically, have received a great deal of attention due to their unusual optical properties. The nanoscale confinement of electrons on the surface of gold nanorods grants them aspect ratio-dependent properties not seen in larger particles. Due to the intriguing properties of GNRs, significant work has gone into the application of nanorods for sensing and detection of various an alytes in biological and other systems. The major modalities which have been developed for these applications are based on: i) morphology-changes, ii)refractive index changes, iii) assembly and iv) surface enhanced Raman scattering.In this report we use the first strategy (morphology-change) for detection of nitrite based on etching of GNRs accompanied by changes in aspect ratios (length/width) in acidicmedium using high aspect ratio of GNRs. Linear calibration graph were obtained in two concentration range of 0.001-0.010 and 0.1-20.0 μ fo nit it . D t ction i it σ of 0.57nMw asobtained for this method. The method was applied successfully to the determination of nitrite in tap water and 3 brand of sussages.
    Transmission electron microscopy (TEM) was used to characterize the size and shape evolution of the etched products.Moreover,we have developed a novel simple and selective colorimetric assay for the determination of glutathione (GSH). This method is based on transverse overg rowth on AuNRs induced by the binding of GSH onto their ends. During overgrowth in acidic medium,with addition of Auprecursor, Au NRs become wider and their lengths stay unchanged and longitudinal plasmon peak gradually blue shifts. The overgrowth was performed at varying GSH concentrations; Decreasing aspect ratio is dependent on amount of preferential bin ing of GSH onto G Rs’ n s. This f ntia bin ing is obab y u to th fact that the CTAB bilayer is less ordered at the ends than that at the side surfaces of Au NRs.
    Linear calibration graph were obtained in two concentration range of 0.05-1.00 and 1-20 μ for Glutathione; Detection Limit σ 0.13μM was obtained in this method
  9. Keywords:
  10. Gold Nanorods ; Colorimetric ; Nitrite ; Corrosion ; Morphology-Changes

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