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    Design of a ratiometric fluorescence nanoprobe to detect plasma levels of levodopa

    , Article Microchemical Journal ; Volume 148 , 2019 , Pages 591-596 ; 0026265X (ISSN) Moslehipour, A ; Bigdeli, A ; Ghasemi, F ; Hormozi Nezhad, M. R ; Sharif University of Technology
    Elsevier Inc  2019
    Abstract
    Simply obtained by the oxidation of levodopa in alkaline media, polylevodopa nanoparticles are able to quench the fluorescence emission of CdTe quantum dots (QDs) via energy transfer mechanism. The extent of this quenching can be exploited for the quantification of levodopa, as an important therapeutic agent in the treatment of Parkinson's disease. However, to effectively improve the detection performance, in this study, we have designed a ratiometric probe by making use of variations in both the emission of QDs and the intrinsic emission of polylevodopa nanoparticles. The enhanced sensitivity, in particular, arose from the measurement of the ratio of fluorescence intensities at two... 

    Enhancement of Kerr nonlinearity at long wavelength in a quantum dot nanostructure

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 43, Issue 10 , August , 2011 , Pages 1759-1762 ; 13869477 (ISSN) Hossein Asadpour, S ; Sahrai, M ; Sadighi Bonabi, R ; Soltani, A ; Mahrami, H ; Sharif University of Technology
    2011
    Abstract
    The giant Kerr nonlinearity with reduced linear and nonlinear absorption in a four-level quantum dot by employing the tunnel coupling is investigated. It is shown that by enhancement of tunnel coupling value the Kerr nonlinearity increases and at the same time linear and nonlinear absorption reduces at the long wavelength which is very important for communicational applications. Enhanced of Kerr nonlinearity in a double quantum dots is investigated. It is found that the electron tunneling has an essential role to reducing the linear absorption and increasing the Kerr nonlinearity at long wavelength  

    Supramolecular hybrid nanomaterials as drug delivery systems

    , Article Supramolecular Chemistry ; Volume 23, Issue 6 , Apr , 2011 , Pages 411-418 ; 10610278 (ISSN) Adeli, M ; Hakimpour, F ; Sagvand, M ; Jaafari, M. R ; Kabiri, R ; Moshari, Z ; Sharif University of Technology
    2011
    Abstract
    Highly fluorescent and water-soluble cadmium selenide quantum dots (QDs) functionalised by thio-cyclodextrin (HS-CD) and mercaptoacetic acid (MAA) as surface coating agents (QDs-CD-MAA) were synthesised successfully. The synthesised hybrid nanomaterials, QDs-CD-MAA, were able to form water-soluble complexes with paclitaxel and folic acid. QDs and their complexes were characterised by usual spectroscopy and microscopy methods. Size and morphology of functionalised QDs were dependent on their capping agents and guest molecules. Short-term in vitro cytotoxicity tests on mouse tissue connective fibroblast adhesive cells (L929) showed that conjugation of CD molecules onto the surface of QDs... 

    Photoluminescent carbon quantum dot/poly-L-Lysine core-shell nanoparticles: A novel candidate for gene delivery

    , Article Journal of Drug Delivery Science and Technology ; 2020 Hasanzadeh, A ; Mofazzal Jahromi, M. A ; Abdoli, A ; Mohammad Beigi, H ; Fatahi, Y ; Nourizadeh, H ; Zare, H ; Kiani, J ; Radmanesh, F ; Rabiee, N ; Jahani, M ; Mombeiny, R ; Karimi, M ; Sharif University of Technology
    Editions de Sante  2020
    Abstract
    Cationic polymers such as poly-L-lysine (PLL) are able to interact electrostatically with DNA to produce polymeric systems with nanometric diameters due to the neutralization and accumulation of DNA. This study integrates the outstanding properties of carbon quantum dots (CQDs) with PLL to develop a novel gene delivery vehicle with a core-shell hybrid nanostructure. The CQD/PLL core-shell nanoparticles (NPs) were, therefore, synthesized in such a way that they had narrow size distribution and an average diameter under 10 nm, both of which were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy exhibited that... 

    A smartphone-based fluorescent electronic tongue for tracing dopaminergic agents in human urine

    , Article ACS Chemical Neuroscience ; Volume 12, Issue 17 , 2021 , Pages 3157-3166 ; 19487193 (ISSN) Shahdost Fard, F ; Bigdeli, A ; Hormozi Nezhad, M. R ; Sharif University of Technology
    American Chemical Society  2021
    Abstract
    The importance of tracing dopaminergic agents in the progression assessment of Parkinson's disease has boosted the demand for fast, sensitive, and real-time multi-analyte detection. Herein, visual and fingerprint fluorimetric patterns have been created by an optical sensor array to simultaneously detect and discriminate among levodopa, carbidopa, benserazide, and entacapone, as important dopaminergic agents. A dual emissive nanoprobe consisting of red quantum dots and blue carbon dots with an overall pink emission has been fabricated to provide unique emission patterns in the presence of the target analytes. The sensor elements in the array come from it's differential response in the absence... 

    Recent advances in the modification of carbon-based quantum dots for biomedical applications

    , Article Materials Science and Engineering C ; Volume 120 , 2021 ; 09284931 (ISSN) Alaghmandfard, A ; Sedighi, O ; Tabatabaei Rezaei, N ; Abedini, A. A ; Malek Khachatourian, A ; Toprak, M. S ; Seifalian, A ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface... 

    Recent advances in the modification of carbon-based quantum dots for biomedical applications

    , Article Materials Science and Engineering C ; Volume 120 , 2021 ; 09284931 (ISSN) Alaghmandfard, A ; Sedighi, O ; Tabatabaei Rezaei, N ; Abedini, A. A ; Malek Khachatourian, A ; Toprak, M. S ; Seifalian, A ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface... 

    Self-assembly, stability, and photoresponse of PbS quantum dot films capped with mixed halide perovskite ligands

    , Article Materials Research Bulletin ; Volume 147 , 2022 ; 00255408 (ISSN) Aynehband, S ; Mohammadi, M ; Poushimin, R ; Azar, M. H ; Nunzi, J. M ; Simchi, A ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    The type of passivating ligands and the ligand exchange method influence the quality of lead sulfide quantum dot films. This imparts on the efficiency of optoelectronic devices. To get a compact arrangement of the nanocrystals in a thin film (⁓100 nm) via self-assembling, we used organic-inorganic perovskites with mixed halides for the solid-state exchange of oleic acid ligands on PbS QDs (⁓ 4 nm). Formamidinium lead halides FAPbIxBr3-x (x= 3,2,1,0) were used. X-ray spectroscopy shows that successful replacement of oleic acid with FA happens by short immersion of the films (2 min) in the solution. Transmission electron microscopy shows that nano-scale cracks, short-range ordering, and fusion... 

    Simply synthesized TiO2 nanorods as an effective scattering layer for quantum dot sensitized solar cells

    , Article Chinese Physics B ; Vol. 23, issue. 4 , 2014 Samadpour, M ; Zad, A. I ; Molaei, M ; Sharif University of Technology
    Abstract
    TiO2 nanorod layers are synthesized by simple chemical oxidation of Ti substrates. Diffuse reflectance spectroscopy measurements show effective light scattering properties originating from nanorods with length scales on the order of one micron. The films are sensitized with CdSe quantum dots (QDs) by successive ionic layer adsorption and reaction (SILAR) and integrated as a photoanode in quantum dot sensitized solar cells (QDSCs). Incorporating nanorods in photoanode structures provided 4- to 8-fold enhancement in light scattering, which leads to a high power conversion efficiency, 3.03% (Voc = 497 mV, Jsc = 11.32 mA/cm2, FF = 0.54), in optimized structures. High efficiency can be obtained... 

    Relative intensity noise study in two mode quantum dot laser

    , Article Optica Applicata ; Volume 41, Issue 4 , 2011 , Pages 961-970 ; 00785466 (ISSN) Horri, A ; Mirmoeini, S. Z ; Faez, R ; Sharif University of Technology
    2011
    Abstract
    In this paper, for the first time, we present a semiclassical noise model for InAs/GaAs quantum dot (QD) laser considering two photon modes, i.e., ground and first excited states lasing. This model is based on the five level rate equations. By using this model, the effect of temperature variations on relative intensity noise (RIN) of QD laser is investigated. We find that the RIN significantly degrades when excited state (ES) lasing emerges at high temperature. Furthermore, we investigate the influence of the quantum dot numbers on the RIN properties  

    Three-dimensional Graphene Electrode for Depleted-hetreojunction Quantum Dot Solar Cells

    , Article Procedia Engineering, 28 June 2015 through 3 July 2015 ; Volume 141 , 2016 , Pages 38-46 ; 18777058 (ISSN) Tavakoli, M. M ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    Herein, a simple and novel method was used to synthesize a new structure of graphene which can be called hollow graphene. First, the ZnO-Graphene QDs synthesized by solution method and then ZnO QDs were dissolved from this structure using an acidic solution to obtain hollow structure of graphene. Afterward, this structure was used in PbS QDs solar cell in order to improve the transport of electron and decrease the recombination of the carriers. A power conversion efficiency of 5.3% was obtained using hollow graphene as a fast electron extraction layer due to the enhancement of EQE and current density. The improvement of PCE in this device was corresponded to efficient photosensitized... 

    The Effect of Graphene Quantum Dots Addition in Modifying 1D ZnO Nanostructured Photocatalysts

    , Ph.D. Dissertation Sharif University of Technology Ebrahimi, Mahdi (Author) ; Moshfegh, Alireza (Supervisor)
    Abstract
    In this research, two type of graphene quantum dots (GQDs) have synthesized including, normal GQDs and nitrogen-doped GQDs (N-GQDs). Then, each of GQDs were deposited on the 1 dimensional zinc oxide (ZnO) nanostructures namely nanowires (NWs) and branched hierarchical (BH) systems. Then, photocatalytic activity of the samples were studied in photodegradation of methylene blue (MB) and methylene orange (MO) under visible light. First, ZnO nanowires (ZnO NWs) were fabricated by anodization of zinc sheet possessing wurtzite crystal structure with their average length and diameter measured in the range of 50-60 μm and 170-300 nm, respectively. Then, normal GQDs were synthesized by... 

    Incorporation of CsPbI3 Perovskite Quantum Dots as Interrfacial Layer for Highly Efficient Cs0.05MA0.95PbI3 Perovskite Solar Cells

    , M.Sc. Thesis Sharif University of Technology Kamraninejad, Vahid (Author) ; Simchi, Abdolreza (Supervisor)
    Abstract
    Despite the excellent photovoltaic performance of perovskite solar cells (PSCs), the instability of PSCs under severe environment (e.g., humidity, intense light) limits further commercialization of such devices. Therefore, in recent years, many researches are conducted on utilizing Perovskite Quantum Dots (PQDs) to enhance performance of PSCs. Herein, CsPbI3 PQDs interfacial layer is incorporated in the perovskite/hole transport material (HTM) interface, on the purpose of increasing charge carrier mobility and preventing electron-hole recombination to increase performance of the PSCs. CsPbI3 PQDs is synthesized at 170℃ with oleic acid and oleylamine as organic ligands by hot-injection... 

    Tunable spherical graphene surface plasmon amplification by stimulated emission of radiation

    , Article Journal of Nanophotonics ; Volume 13, Issue 2 , 2019 ; 19342608 (ISSN) Ardakani, S. B ; Faez, R ; Sharif University of Technology
    SPIE  2019
    Abstract
    A structure is suggested for spasing. The presented surface plasmon amplification by stimulated emission of Radiation (SPASER) is made up of a graphene nanosphere, which supports localized surface plasmon modes, and a quantum dot array, acting as a gain medium. The gain medium is pumped by an external light source. Since all the plasmons are carried on a graphene platform, the structure features coherent surface plasmons with high confinement and large life time. All the structures are analyzed theoretically using full quantum mechanical description. The main advantage of the proposed SPASER is its simple tuning capability of changing graphene's Fermi level, which is performed by either... 

    Optical nanoprobes for chiral discrimination

    , Article Analyst ; Volume 145, Issue 20 , 2020 , Pages 6416-6434 Bigdeli, A ; Ghasemi, F ; Fahimi Kashani, N ; Abbasi Moayed, S ; Orouji, A ; Jafar Nezhad Ivrigh, Z ; Shahdost Fard, F ; Hormozi Nezhad, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2020
    Abstract
    Chiral discrimination has always been a hot topic in chemical, food and pharmaceutical industries, especially when dealing with chiral drugs. Enantiomeric recognition not only leads to better understanding of the mechanism of molecular recognition in biological systems, but may further assist in developing useful molecular devices in biochemical and pharmaceutical studies. By emerging nanotechnology and exploiting nanomaterials in sensing applications, a great deal of attention has been given to the design of optical nanoprobes that are able to discriminate enantiomers of chiral analytes. This review explains how engineering nanoparticles (NPs) with desired physicochemical properties allows... 

    Analytical results on coherent conductance in a general periodic quantum dot: Transfer matrix method

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 28, Issue 2 , 2005 , Pages 150-161 ; 13869477 (ISSN) Mardaani, M ; Shokri, A. A ; Esfarjani, K ; Sharif University of Technology
    2005
    Abstract
    In this work, we study the conductance of a general periodic quantum dot (QD) attached to ideal semi-infinite uniform metallic leads (nanocrystals), fully analytically. We propose a new general formula which relates conductance to transfer matrix (TM) for an isolated cell in the periodic dot. The equation describes exactly the dependence of the transmission coefficient (TC) on Fermi energy, dot-size, dot-lead coupling, and gate voltage for an arbitrary periodic dot. Then, we derive a nonlinear equation which gives the resonance, bound, and surface state energies. Finally, the TC has been calculated for gapless, single, and double gap models exactly. Moreover, we have also calculated the... 

    Quantum-Dot Cellular Automata (QCA): Theory and Application

    , M.Sc. Thesis Sharif University of Technology Sadat Bashiri, Fereshteh (Author) ; Faez, Rahim (Supervisor) ; Bagheri Shouraki, Saeed (Supervisor)
    Abstract
    Quantum-Dot Cellular Automata (QCA) is a novel field of nanotechnology which is being designed and implemented in molecular scales. It has major advantageous over transistor based technology such as: low power consumption, high information transition speed, small size and high density. It has been shown that conventional transistor based circuits can be implemented in this nanotechnology with less complexity. Furthermore, binary circuits can be implemented in QCA technology since QCA cells have only two independent and equivalent states. So, QCA provides appropriate space for computational circuits. The aim of computational circuits design is to achieve small size and high speed processors.... 

    Joint mapping of mobility and trap density in colloidal quantum dot solids [electronic resource]

    , Article Journal of ACS nano ; 2013, Vol.7, No. 7, P.5757-5762 Stadler, Philipp ; Sutherland, Brandon R ; Ren, Yuan ; Ning, Zhijun ; Simchi, A. (Arash) ; Thon, Susanna M ; Hoogland, Sjoerd ; Sargent, Edward H ; Sharif University of Technology
    Abstract
    Field-effect transistors have been widely used to study electronic transport and doping in colloidal quantum dot solids to great effect. However, the full power of these devices to elucidate the electronic structure of materials has yet to be harnessed. Here, we deploy nanodielectric field-effect transistors to map the energy landscape within the band gap of a colloidal quantum dot solid. We exploit the self-limiting nature of the potentiostatic anodization growth mode to produce the thinnest usable gate dielectric, subject to our voltage breakdown requirements defined by the Fermi sweep range of interest. Lead sulfide colloidal quantum dots are applied as the active region and are treated... 

    Self‐assembled, nanowire network electrodes for depleted bulk heterojunction solar cells (Adv. Mater. 12/2013) [electronic resource]

    , Article Journal of Advanced Materials ; March 2013, Vol. 25, Issue 12, PP. 1768 Lan, X. (Xinzheng) ; Bai, Jing ; Masala, Silvia ; Thon, Susanna M ; Ren, Yuan ; Kramer, Illan J ; Hoogland, Sjoerd ; Simchi, A. (Abdolreza) ; Koleilat, Ghada I ; Paz‐Soldan, Daniel ; Ning, Zhijun ; Labelle, André J ; Kim, Jin Young ; Jabbour, Ghassan ; Sargent, Edward H ; Sharif University of Technology
    Abstract
    A solution-processed, bottom-up nanowire network electrode is developed and employed in a bulk heterojunction colloidal quantum dot solar cell. The electrode features a ZnO template which is converted into locally connected, infi ltratable TiO2 nanowires. The new electrode allows the application of a thicker light absorbing fi lm without compromising the charge extraction, as reported by Edward H. Sargent, Ghassan Jabbour, and co-workers on page 1769. The frontispiece shows schematically the electrode shape and the resultant device architecture  

    The noise equivalent circuit model of quantum-dot lasers

    , Article Journal of Russian Laser Research ; Volume 33, Issue 3 , May , 2012 , Pages 217-226 ; 10712836 (ISSN) Horri, A ; Mirmoeini, S. Z ; Faez, R ; Sharif University of Technology
    2012
    Abstract
    We derive the noise equivalent circuit model of semiconductor self-assembled quantum-dot (QD) lasers (SAQDL) from the rate equations including Langevin noise sources. This equivalent circuit allows a straightforward calculation of the noise of an SAQDL combined with electronic components. Using the presented model, we study how the carrier dynamics influences relative intensity noise (RIN) of QD lasers. We demonstrate that RIN is degraded with larger inhomogeneous broadening. Furthermore, we show that RIN is enhanced for lower quantum-dot coverage level