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توسعه حسگرهای نسبت سنجی فلورسانس بر پایه نانوساختارهای نورتاب به منظور تشخیص های چشمی
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توسعه حسگرهای نسبت سنجی فلورسانس بر پایه نانوساختارهای نورتاب به منظور تشخیص های چشمی

فرهمند نژاد، محمد امین Farahmand Nejad, Mohammad Amin

Development of Ratiometric Sensors Based on Fluorescent Nanostructures for Naked Eye Detection

Farahmand Nejad, Mohammad Amin | 2019

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52431 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Hormozi-Nezhad, Mohammad Reza
  7. Abstract:
  8. In the first part of this research, we have developed a simple and effective ratiometric fluorescence sensor for selective detection of dopamine (DA) in alkaline media by simply mixing thioglycolic acid (TGA) functionalized orange fluorescent cadmium telluride (CdTe) quantum dots (QDs) with amino-functionalized blue fluorescent carbon nanodots (CDs). Under a single excitation wavelength of 365 nm, the sensor exhibits dual-emissions centered at 445 and 603 nm. The fluorescence of CdTe QDs is selectively quenched by DA, whereas the fluorescence of CDs is insensitive to the analyte. In the presence of different amounts of DA, the variations in the dual emission intensity ratios exhibit a continuous color change from pink to purple and to blue, which can be clearly observed with the naked eye. The ratiometric fluorescent probe has been successfully applied for the detection of DA in urine with a detection limit of 1.3 μM. To facilitate their practical use, ratiometric fluorescent probe–agarose hydrogels were prepared as instrument-free and simple platforms for visual detection of DA
    In the third part of this research, a visual approach for sensitive detection of sulfide was developed by simply mixing orange emissive glutathione stabilized gold nanoclusters (AuNCs) and blue emissive urea stabilized carbon dots (CDs) in an appropriate ratio within a ratiometric fluorescence (RF) strategy. Under a single excitation wavelength of 365 nm, the RF probe exhibited a dual emission at 452 and 607 nm corresponding to CDs and AuNCs, respectively. Owing to the high affinity of sulfide ions to AuNCs in alkaline medium, the orange fluorescence of AuNCs was selectively quenched while the CDs emission remained unchanged, resulting in a distinguishable fluorescence color change from pink to blue under a UV lamp. The I452/I607 ratio was linearly dependent to sulfide concentration in the range of 1.0 to 50.0 µM with a limit of detection (LOD) of 0.35 µM. The proposed approach was successfully applied for the detection of sulfide in river water with acceptable recoveries
  9. Keywords:
  10. Naked Eye Detection ; Ratiometric Fluorescence ; Fluorescence Nanostructures ; Quantum Dot ; Carbon Dots ; Dopamine ; Sulfide ; Lateral Flow ; Immunoassay

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