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    Fabrication and Characterization of Novel Metallic Nanostructured Substrates for Surface-Enhanced Raman Scattering

    , M.Sc. Thesis Sharif University of Technology Radmand, Amir (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    Noble metallic nanostructures based on their localized surface plasmon resonance (LSPR) exhibit a phenomenon known as surface-enhanced Raman scattering (SERS) in which the scattering cross sections are dramatically enhanced for molecules adsorbed thereon. The enhancement factor (EF) in typical cases can reach 106 and in recent years, it has been reported that even single-molecule spectroscopy is possible by SERS, suggesting that the EF can be as much as 1014-1015. In this study, we report a simple method to synthesize nanostructures of Ag and Au on metallic wafers and semiconductor via electroless deposition method. This approaches has been demonstrated to deposit metal nanostructures, thin... 

    Determination of Hydrazine and Phenylhydrazine Based on Formation of Gold Nanoparticles Stabilized with Non-ionic Surfactants

    , M.Sc. Thesis Sharif University of Technology Karami, Pari (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    A simple and effective procedure is proposed for colorimetric detection of hydrazine and phenylhydrazine. It was found that the reduction of AuCl4- to gold nanoparticles (Au-NPs) by these compunds in the presence of Tween-20 as a stabilizing agent produced very intense surface plasmon resonance peak of Au-NPs. The plasmon absorbance of the Au-NPs allows the quantitative spectrophotometric detection of the hydrazine and phenylhydrazine. The calibration curves derived from the changes in absorbance at λ = 530 and λ = 550 nm for hydrazine and phenylhydrazine, respectively were linear with concentration of hydrazine and phenylhydrazine in the range of 1.0×10-6- 2.0×10-4 M, 5×10-6 - 4×10-4 M,... 

    Development of Nano-QSARs as Predictive Tools for Nanomaterials’ Cytotoxicity

    , Ph.D. Dissertation Sharif University of Technology Bigdeli, Arafeh (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    The increasing role of nanotechnology in our every-day-life, has aroused global concern regarding their hazardous potential, resulting in a demand for parallel risk assessment. Quatitative structure-activity relationships enable researches to use unique properties of nanoparticles as predictors for their toxicity or any other biological response. Extracting rational correlations between physicochemical properties of nanoparticles and their biological response, not only reveals the way that nanoparticles behave upon entering into biological media, but also leads to the design of safer and efficient nanoparticles for various applications of interest. This PhD dissertation presents QSAR tools... 

    Colorimetric Sensor Array Design for Classification and Detection of Nanoparticles and Some Biomolecules

    , Ph.D. Dissertation Sharif University of Technology Ghasemi, Forough (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    In the first part of this research, we reported a liquid sensor array for detection and classification of biological thiols, based on aggregation of gold nanoparticles (AuNPs) with different coatings as sensor elements. Thiol mediated aggregation of AuNPs was visualized via UV–vis spectra. The spectral changes, as a consequence of aggregation of AuNPs, made a unique pattern of spectra for each analyte and allowed for the selective detection and discrimination of the biological molecules. HCA and PCA analysis demonstrated the discrimination of various thiols of different concentrations (i.e. 10–800 mmol L-1 for cysteine, 200–700 mmol L-1 for both glutathione and glutathione disulfide).... 

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

    , M.Sc. Thesis Sharif University of Technology Fahimi - Kashani, Nafiseh (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    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... 

    Label-Free Colorimetric Detection of Methiocarb Insecticid Based on Aggregation of Gold Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Mohammadi Avizi, Ali Akbar (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    Methiocarb [3,5-dimethyl-4-(methylthio) phenyl methylcarbamate] is an N-methylcarbamate with neurotoxic action. Because carbamate pesticides are acetylcholinesterase inhibitors, they are considered to be carcinogens and mutagens. Methiocarb pesticide is widely used throughout the world particularly effective as fungicides, insecticide and bird repellent. To prevent its harmful effects on animals, humans, and the environment, it is of crucial importance to develop simple and sensitive methods for in-situ detection of methiocarb. This research describes a simple and low-cost method for on-site monitoring of methiocarb insecticide. Gold nanoparticles (AuNPs) aggregation caused by methiocarb,... 

    Colorimetric Determination of Tizanidine and Mercury (II) Based on Aggregation and Anti-aggregation of Gold Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Yahyazadeh, Ehsan (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    In the first section of this research, we have developed a simple and rapid colorimetric method for determination of tizanidine using citrate capped gold nanoparticles. Under optimal conditions, the AuNPs easily aggregate upon addition of tizanidine and the solution color changes from red to gray. This color change was followed using a UV-Vis spectrophotometer. The detection limit was calculated to be 0.48 µM. The method was successfully applied for determination of tizanidine in Spalex© tablets. In the last section, the anti-aggregation effect of Hg(II) on the tizanidine-AuNPs system was utilized with the aim of developing a colorimetric method for detection of Hg(II). Addition of... 

    Design of an Optoelectronic Tongue Based on Anti-Aggregation of Gold Nanoparticles for Detection and Classification of Heavy Metal Ions

    , M.Sc. Thesis Sharif University of Technology Najafzadeh, Fatemeh (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    The first report of anti-aggregation-based sensor arrays is presented. The strategy is based on the competitive interaction of citrate-capped gold nanoparticles (AuNPs) and heavy metal ions (i.e., Hg(II), Ag(I), Fe(III), and Pb (II)) with three aggregation reagents (i.e., cysteine, melamine, and arginine). In the presence of aggregation reagent,the color and UV–vis spectra of AuNPs are changed indicating the aggregation ofAuNPs. Addition of the aggregation reagents which are firstly treated with the ions, causes AuNPs turn from the aggregation to the dispersion state. The anti-aggregation capability of ions towards various aggregation reagents is different because of distinct stability... 

    Spectrophotometric Determination of Copper Ions and Pamidronate Disodium Based on Changing the Surface Plasmon Resonance Band of Au Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Abbasi-Moayed, Samira (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    In recent years, metallic nanoparticles, specially gold and silver nanoparticles, have received great attention for biological and metal ions analysis, due to the surface plasmon resonance phenomena. Gold nanoparticles (AuNPs) have recently gained much interest in colorimetric probe based on aggregation or anti-aggregation of AuNPs, due to their simplicity and having high order of magnitude extinction coefficients, in addition to the dependence of surface plasmon resonance wavelength and intensity on the interparticles distances. In the first part of this thesis, a highly sensitive colorimetric method for detection of copper ions based on anti-aggregation of citrate capped AuNPs was... 

    Synthesis of Luminescent Carbon Dots for Selectivity Study Towards Metal Ions

    , M.Sc. Thesis Sharif University of Technology Ghasemi, Nazer Hossein (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    Today, the use of graphene quantum dots has been very much considered due to easy synthesis methods, strong fluorescence emission, and many sources of synthesis. In this study, the effect of changing capping agent of graphene quantum dots toward iron (Ⅲ), copper (Ⅱ) and mercury (Ⅱ) ions was studied. The linear range of response of the graphene quantum dots synthesized with ethylenediamine for mercury (Ⅱ) and iron (Ⅲ) ions was 10-70 µM, and this sensor also responded to Cu (Ⅱ) ions. Urea synthesized graphene quantum dots also responded to all three ions. The linear range of the response for mercury (Ⅱ) , iron (Ⅲ) and copper (Ⅱ) ions was 5-25, 10-70 and 120-120 μM respectively. The linear... 

    Optical Sensor Arrays Based on Nanostructured Materials for Quantitative Detection and Qualitative Discrimination of Pesticides and Structural Isomers

    , Ph.D. Dissertation Sharif University of Technology Fahimi-Kashani, Nafiseh (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    There is a growing interest in developing high-performance sensors monitoring organophosphate pesticides, primarily due to their broad usage and harmful effects on mammals. In the first part of this research, by introducing conditional sensor elements (CSE), a colorimetric sensor array has been proposed for the detection and discrimination of several organophosphate pesticides (OPs). citrate-capped 13 nm gold nanoparticles (AuNPs) at nine different pH/ionic strengths were employed as simple plasmonic sensing elements in the development of a colorimetric sensor array for the detection and discrimination of five organophosphate pesticides, including azinphos-methyl (AM), chlorpyrifos (CP),... 

    Detection of L-Dopa Based on Fluorescent of levodopa Nanopolymers and CdTe Quantum Dots

    , M.Sc. Thesis Sharif University of Technology Moslehipour, Ahmad (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    Levodopa [L-3, 4-dihydroxyphenylalanine, or L-DOPA] is an important neurotransmitter used for the treatment of neural disorders such as Parkinson’s disease. Abnormal L-Dopa concentrations in biological fluids can be used for evaluation of diseases such as Parkinson’s diseases. In the first part of this thesis, a rapid and sensitive method for levodopa detection was reported which is based on in situ formation of polylevodopa nanoparticles. The assay is very simple and low cost and uses only NaOH and HCl as reagents. Under alkaline conditions, levodopa is spontaneously oxidized to its quinone derivative and shows the fluorescence properties. The fluorescence signal of the oxidation product of... 

    Spectrophotometric Determination of D - L-Penicillamine Using Red Shift on the Surface Plasmon Resonance Band of Au Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Azargun, Mohammad (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    We report herein the development of a highly sensitive colorimetric method for detection of D- Penicillamine using citrate capped gold nano particles (Au-NPs) .This assay relies upon the distance-dependent of gold nanoparticles surface plasmonic resonance band of gold nanoparticles. By replacing the thiol-containg chelator drug, D-Penicillamine, with citrate on the gold nano particles surface, a new peak appearing at a longer wavelength intensifies and shifts further to the red from the original peak position which depends on ionic strength, D- Penicillamine and gold nanoparticles. The ratio intensities of absorbance at longer wavelength (630 nm) to original wavelength (521 nm) allow the... 

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

    , Ph.D. Dissertation Sharif University of Technology Farahmand Nejad, Mohammad Amin (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    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... 

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

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Jamaloddin (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    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... 

    Spectrofluorimetric Determination of Copper Ions Based on Fluorescence Resonance Energy Transfer and Spectrofluorimetric Determination of Iron (III) Ions in the Prescence of Iron (II) Ions Based on Fluorescence Quenching

    , M.Sc. Thesis Sharif University of Technology Taghipour, Mitra (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    The use of fluorophores in metallic and non-metallic analysis, have received great attention for chemical sensing due to the high sensitivity and selectivity. Fluorophores through participating in emission mechanisms, interact with analyte and the emission intensity changes, which leads to determination of analyte concentration. These mechanisms are included fluorescence resonance energy transfer and fluorescence emission quenching. In the first part of this thesis, a highly sensitive probe for detection of copper ions was developed based on fluorescence resonance energy transfer due to the plasmonic peak of citrate capped gold nanoparticles and emission peak of FITC. Quenched emission of... 

    Spectrofluorimetric Determination of D-penicillamine Using FITC-capped Gold Nanoparticles Via Flourescence Resonance Energy Transfer Mechanism

    , M.Sc. Thesis Sharif University of Technology Zargar, Tahereh (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    Recently, fluorescence resonance energy transfer (FRET) based assay through employing gold nanoparticles have been developed for sensitive and selective detection of various analytes [1,2]. These are due to the extremely high extinction coefficient of Au NPs, which induces fluorescence quenching of the attached fluorophores as a result FRET ; a process which is inversely proportional to the sixth power of the distance between fluorophore and quencher [3]. Upon the addition of the analytes with much stronger affinity for Au NPs, the fluorophore molecules are detached from the surface of the Au NPs results in an increase of fluorescence intensity, which is in direct relation with... 

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

    , M.Sc. Thesis Sharif University of Technology Seyyed Hosseini, Ensieh (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    Abstract
    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... 

    Aggregation-Based Colorimetric Sensor for Determination of Prothioconazole Fungicide Using Colloidal Silver Nanoparticles (AgNPs)

    , M.Sc. Thesis Sharif University of Technology Jafar-Nezhad Ivrigh, Zahra (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    There is a growing interest in developing high-performance sensors monitoring fungicides, due to their broadly usage and their adverse effects on humans and wildlife. In the present study, a colorimetric probe has been proposed for detection of prothioconazole based on aggregation of unmodified silver nanoparticles (AgNPs). Under optimized condition, linear relationships between the concentration of prothioconazole and the absorbance ratio of A500/A395 were found over the range of 0.01 µg. mL-1 to 0.4 µg. mL-1 with Detection limit as low as 1.7 ng. mL-1. Furthermore, AgNPs color change from yellow to pink-orange in presence of prothioconazole, indicates highly sensitive naked-eye... 

    The Interaction Study of Thio-Organophosphate Pesticides with Colloidal Silver Nanoparticles for Colorimetric Sensing Applications

    , M.Sc. Thesis Sharif University of Technology Rahimi, Sogol (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)
    Abstract
    Pesticides are broadly applied in croplands, glasshouses, and orchards in order to increase agricultural products and their quality. Among the variety of pesticides, organophosphorus pesticides (OPs), possessing high insecticidal activity, acute toxicity and relatively short environmental persistence, have been widely used for pest control in agriculture. However, this effect might lead to adverse health impacts or death for mammals and humans. Thus, even at trace levels, it is of great importance to develop a simple, sensitive, inexpensive and real-time detection method for monitoring the levels of pesticides in the environment, foodstuffs and biological samples. The integration of metallic...