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Developments of Fluorescence Sensor Arrays Using Nanostructured Sensor Elments and Nanocellulose Substrate for Identification and Discrimination of Biomolecules and Environmental pollutants

Abbasi-Moayed, Samira | 2019

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52440 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Hormozi-Nezhad, Mohammad Reza; Golmohammadi Ghaneh, Hamed
  7. Abstract:
  8. In the first part of this research, a ratiometric fluorescent sensor array has been developed on nanocellulose platform towards chemical discrimination applications. Bacterial nanocellulose (BC) was utilized for the first time as a novel, flexible and transparent substrate in optical sensor arrays for developing portable and high performance sensor array.. To fabricate this platform, the hydrophobic walls on BC nanopaper substrates were successfully created using laser printing technology. In addition, we have used the properties of immobilized ratiometric fluorescence sensor elements (Carbon Dots- Rhodamine B (CDs-RhB) nanohybrids) on nanopaper platform to improve the visual discrimination analysis. Heavy metal ions (i.e. Hg (II), Pb (II), Cd (II), Fe (III) and Cu (II)) were utilized as a model analytes to verify the applicability of fabricated nanopaper based ratiometric fluorescent sensor array (NRFSA). The color variation of NRFSA platform upon addition of heavy metal ions were obtained by a smartphone (under an UV irradiation). Therefore, five heavy metal ions (20.0-100.0 µM) have been well distinguished through RGB analysis by producing characteristic PL fingerprint-like response patterns for each of which. Moreover, the developed optical sensor array was exploited to identify heavy metal ions in water and fish samples.We also found that the PL spectra of the developed NRFSA, which were recorded by a spectrofluorometer, can be exploited for discrimination applications. It was also found that the PL spectra of the developed NRFSA in the prescence of metal ions, which were recorded by a spectrofluorometer, can be exploited for discrimination applications.In the second part of this research, a ratiometric fluorescence (RF) sensor array have been developed with a wide color emissive variation, for visual identification and discrimination of biothiols (i.e. Cysteine, Gluthathione, Gluthathionedisulfide and systeamine). To this aim, ratiometric fluorescence sensors including N-Acetyl L-Cysteine capped green CdTe quantum dots -Rhodamin B (GQDs-RhB) and red CdTe QDs- carbon dots (RQDs-CDs) in the absence and prescence of NaOH (5 mM) were utilized as sensor elements. Owing to the high affinity of thiols group (SH) to the surface of CdTe QDs and the aggregation of QDS, the fluorescence (FL) emission of QDs changed while the emission of CDs and rhodamine B were remained almost unchanged upon the addition of biothiols. Accordingly, specific patterns like fingerprint patterns were created for each biothiols which were then distinguished both visually and spectroscopically. Hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA) pattern recognition techniques were employed for the identification and discrimination of biothiols. Based on the designed RF sensor array, convenient test strips were fabricated on BC nanopaper for visual discrimination of biothiols. This sensor can successfully identify biothiols in human plasma.In the third part of this research, in order to rapid identification and discrimination of catecholamine neurotransmitters (i.e. dopamine, norepinephrine, levodopa) in the presence of ascorbic acid (AA), the fluorescence sensor array was constructed by combining sensor elements including blue Carbon dots (BCDs), green CdTe QDs (GQDs) and red CdTe QDs into a single well platform. This sensor demonstrates three ternary- fluorescence emission at 450, 520 and 630 nm under a single wavelength excitation (360 nm). The intensity of the sensor elements changed differently in the prescence of target analytes. Therefore, to produce distinct fluorescence response patterns in a single fluorimetric test, the spectral and corresponding images of multichannel fluorescence probe were monitored in the presence of catecholamine neurotransmitters and AA. Finally, pattern recognition analyses of the fluorescence variations data in three wavelength allow identification and discrimination of catecholamine neurotransmitters and also AA in concentration range of 10.0-100.0 µM. The developed sensor can be used for identification of catecholamine neurotransmitters in urine sample.In the forth part of this research, NaYF4: Yb, Er/Tm upconversion nanoparticles (UCNPs) were utilized for designing a multichannel sensor array for discrimination of four important neurotransmitters including dopamine, levodopa, norepinephrine and serotonine. This efficient sensor array was developed by exploiting the existence of several emission peaks of UCNPs that are related to the energy levels of the lanthanide ions. The oxidation products of neurotransmitters at alkaline condition, act as quencher for upconversion fluorescence according to a electron-transfer mechanism. Furthermore, the performance of the proposed sensor array was confirmed by discrimination among individual neurotransmitters and their mixtures, as well as identification of these neurotransmitters in artificial cerebrospinal fluid (aCSF)
  9. Keywords:
  10. Sensors Array ; Fluorescence Sensors ; Quantum Dot ; Carbon Dots ; Upconversion Nanoparticles ; Neuro Transmitter ; Metal Ions ; Nanocellulose

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