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    Modification of a glassy carbon electrode with a bilayer of multiwalled carbon nanotube/benzene disulfonate-doped polypyrrole: Application to sensitive voltammetric determination of olanzapine

    , Article RSC Advances ; Vol. 4, Issue. 76 , Aug , 2014 , pp. 40553-40560 ; ISSN: 20462069 Shahrokhian, S ; Azimzadeh, M ; Hosseini, P ; Sharif University of Technology
    Abstract
    A glassy carbon electrode was coated with a thin layer of multi-walled carbon nanotubes and subsequently was electro-polymerized with polypyrrole. The prepared electrode was used for the voltammetric determination of olanzapine (OLZ). The peak current of OLZ increases remarkably on the surface of the modified electrode. This is due to the large increase in the microscopic area of the electrode surface along with the strong adsorption of OLZ on the surface of the electrode. The film modifier was characterized by scanning electron microscopy, atomic force microscopy and cyclic voltammetry techniques. Experimental variables, such as deposited amount of nanotube suspension, pH of the supporting... 

    Electrochemical Redox Behaviour of Temozolomide Using a Glassy Carbon Electrode

    , Article Electroanalysis ; Volume 22, Issue 22 , September , 2010 , Pages 2633-2640 ; 10400397 (ISSN) Ghalkhani, M ; Fernandes, I. P. G ; Oliveira , S. C. B ; Shahrokhian, S ; Oliveira Brett, A. M ; Sharif University of Technology
    2010
    Abstract
    The electrochemical behaviour of temozolomide on a glassy carbon electrode has been investigated. The reduction of temozolomide is an irreversible process, pH dependent, and the mechanism involves the addition of one electron and one proton to C5 to form an anion radical, causing the irreversible breakdown of the tetrazinone ring. The oxidation mechanism of temozolomide is an irreversible, adsorption-controlled process, pH dependent up to value close to the pKa and occurs in two consecutive charge transfer reactions, with the formation of the hydroxylated product. The electroanalytical determination of TMZ led to a detection limit of 1.1 μM  

    Direct electron transfer of myoglobin on CdO nanoparticles modified glassy carbon electrode

    , Article International Journal of Electrochemical Science ; Volume 8, Issue 5 , 2013 , Pages 7345-7356 ; 14523981 (ISSN) Mohammadi, N ; kakavandi, Y. G ; Movassagh, A. A ; Nasereslami, S ; Mohseni, G ; Hajiosseinlo, A ; Sofimaryo, L ; Soleimani, R ; Akbari-dastjerdi, H ; Negahdary, M ; Sharif University of Technology
    2013
    Abstract
    In this study, direct electron transfer of myoglobin (Mb) on cadmium oxide (CdO) nanoparticles modified glassy carbon electrode (GCE) was investigated. Prepared CdO nanoparticles were studied by X-Ray diffraction (XRD) and UV-visible absorption methods. All electrochemical studies were performed by cyclic voltammetry (CV) and a potentiostat device. The cyclic voltammogram of Mb/ CdO Nps/ GCE showed a couple of stable redox and oxidative peaks at -470 and -370 mV at scan rate of 50 mVs-1, respectively. The formal potential (Eo) of myoglobin was calculated as -(420 ± 3) mV. Direct electrode transfer led to design a biosensor for determination of hydrogen peroxide (H2O2). The sensor sensitivity... 

    Electrochemical oxidation mechanisms of the antioxidants daidzein and 7-Hydroxy-4-chromone

    , Article Electroanalysis ; Volume 24, Issue 3 , 2012 , Pages 618-626 ; 10400397 (ISSN) Fernandes, I. P. G ; Oliveira, S. C. B ; Ghalkhani, M ; Shahrokhian, S ; Oliveira Brett, A. M ; Sharif University of Technology
    Abstract
    The electrochemical behavior of antioxidants daidzein (DZ) and 7-hydroxy-4-chromone (7-OH-4-CHM) was investigated. The oxidation of DZ is irreversible, pH-dependent, and occurs in two steps, the first of 4′-OH on the B-ring and the second on the 7-OH on the A-ring. The oxidation of 7-OH-4-CHM occurs on the 7-OH on the A-ring, is irreversible, pH-dependent and proceeds in a single step. The DZ diffusion coefficient was calculated in pH7.0 phosphate buffer to be D DZ=8.1×10 -5cm 2s -1. The detection limits of DZ and 7-OH-4-CHM was calculated as LOD DZ=0.08μM and LOD 7-OH-4-CHM=0.13μM  

    A study of the electro-catalytic oxidation of methanol on a cobalt hydroxide modified glassy carbon electrode

    , Article Electrochimica Acta ; Volume 48, Issue 23 , 2003 , Pages 3423-3429 ; 00134686 (ISSN) Jafarian, M ; Mahjani, M. G ; Heli, H ; Gobal, F ; Khajehsharifi, H ; Hamedi, M. H ; Sharif University of Technology
    2003
    Abstract
    Cobalt hydroxide modified glassy carbon electrodes (CHM/GC) prepared by the anodic deposition in presence of tartrate ions have been used for the electro-catalytic oxidation of methanol in alkaline solutions where the methods of cyclic voltammetery (CV), chronoamperometry (CA) and impedance spectroscopy (IS) have been employed. In CV studies, in the presence of methanol the peak current of the oxidation of cobalt hydroxide increase is followed by a decrease in the corresponding cathodic current. This suggests that the oxidation of methanol is being catalysed through the mediated electron transfer across the cobalt hydroxide layer comprising of cobalt ions of various valence states. A... 

    Ultra-sensitive detection of leukemia by graphene

    , Article Nanoscale ; Vol. 6, issue. 24 , Dec , 2014 , p. 14810-14819 Akhavan, O ; Ghaderi, E ; Hashemi, E ; Rahighi, R ; Sharif Universit of Technology
    Abstract
    Graphene oxide nanoplatelets (GONPs) with extremely sharp edges (lateral dimensions ∼20-200 nm and thicknesses <2 nm) were applied in extraction of the overexpressed guanine synthesized in the cytoplasm of leukemia cells. The blood serums containing the extracted guanine were used in differential pulse voltammetry (DPV) with reduced graphene oxide nanowall (rGONW) electrodes to develop fast and ultra-sensitive electrochemical detection of leukemia cells at leukemia fractions (LFs) of ∼10-11 (as the lower detection limit). The stability of the DPV signals obtained by oxidation of the extracted guanine on the rGONWs was studied after 20 cycles. Without the guanine extraction, the DPV peaks... 

    A comparative investigation of the electrocatalytic oxidation of methanol on poly-NiTCPP and poly-TCPP/Ni modified glassy carbon electrodes

    , Article Journal of Electroanalytical Chemistry ; Volume 663, Issue 1 , December , 2011 , Pages 14-23 ; 15726657 (ISSN) Jafarian, M ; Haghighatbin, M. A ; Gobal, F ; Mahjani, M. G ; Rayati, S ; Sharif University of Technology
    2011
    Abstract
    Electro-oxidation of methanol in alkaline solution at a glassy carbon electrode electrochemically modified by a conductive polymeric meso-tetra(4-carboxyphenyl)porphyrinato nickel(II), abbreviated as poly-NiTCPP and also meso-tetra(4-carboxyphenyl)porphyrin with incorporated nickel(II) cations, abbreviated as, poly-TCPP/Ni, were investigated and compared. Both films were prepared by oxidative electro-polymerization of complexes by repetitive cyclic voltammetry (RCV) in 0.1 M NaOH aqueous solution. The electrochemical properties and behaviors and also kinetic values of both films have been characterized and compared using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical... 

    Amine functionalized TiO2 coated on carbon nanotube as a nanomaterial for direct electrochemistry of glucose oxidase and glucose biosensing

    , Article Journal of Molecular Catalysis B: Enzymatic ; Volume 68, Issue 2 , 2011 , Pages 206-210 ; 13811177 (ISSN) Tasviri, M ; Rafiee Pour, H. A ; Ghourchian, H ; Gholami, M. R ; Sharif University of Technology
    Abstract
    A nano-composite material consisting of amine functionalized TiO 2-coated carbon nanotubes was prepared and used for glucose oxidase (GOx) absorption. The GOx bearing nanomaterial was fixed on a glassy carbon electrode to construct a novel biosensor for glucose determination. The direct electrochemistry of immobilized GOx and its electron transfer parameters at the modified glassy carbon electrode were reported. The apparent heterogeneous electron transfer rate constant (ks) of GOx was estimated to be 3.5 s-1, which is higher than those reported previously. Amperometric detection of glucose resulted in a rapid (3 s) and stable response in the linear concentration range from 1.8 to 266 μM.... 

    Preparation and Investigation of the Electrochemical of the Glassy Carbon Electrode Modified by Nanocellulose/Carbon Nanoparticle: Application to Pharmaceutical Determinations

    , M.Sc. Thesis Sharif University of Technology Balotf, Hamed (Author) ; Shahrokhian, Saeed (Supervisor)
    Abstract
    In the first part, a novel electrochemical sensor for clonazepam (CLNP) was fabricated based on immobilizing cellulose nanofibers /carbon nanoparticles (CNFs/CNPs) nanocomposite on glassy carbon electrode (CNFs/CNPs/GCE). The combination of CNFs and CNPs produced a novel kind of structurally uniform and electro-analytically active nanocomposite. The surface morphology of CNFs/CNPs layer deposited onto glassy carbon electrode was characterized by scanning electron microscopy. The results of the voltammetric investigations showed a considerable enhancement in the cathodic peak current of CLNP (up to 60 times) on the surface of CNFs/CNPs/GCE relative to the bare GCE. Under the optimal... 

    Preparation and Investigation of the Electrochemical Behavior of Sensors Based on Glassy Carbon Electrode Modified with Various Carbon Nanostructures Decorated by Some of Metal Nanoparticlesfor Determination of Ceftizoxime

    , M.Sc. Thesis Sharif University of Technology Ranjbar, Saba (Author) ; Shahrokhian, Saeed (Supervisor) ; Masoumeh Ghalkhani (Co-Advisor)
    Abstract
    In the recent years, sensors and biosensors attracts much attentions as a suitable devices in analytical chemistry. In this meantime carbon nanostructures and metal nanoparticles act as a good choice owing to their unique properties such as high electrical conductivity andmechanical and chemical stability in modification of the surface of sensors and biosensors. Because of importance of analysis the trace amounts of pharmaceutical and biological compounds, in this studies the surface of glassy carbon electrode was modified with some carbon nanostructures and metal nanoparticles for electrochemical investigation and determination of pharmaceutical and clinical compounds.In the first work, a... 

    Fabrication of Applied Electrode Materials based on Metal-Organic Frameworks to Design Non-Enzymatic Electrochemical Sensing Platforms for Measuring of Glucose in Physiological Samples

    , M.Sc. Thesis Sharif University of Technology Ezzati, Milad (Author) ; Shahrokhian Dehkordi, Saeed (Supervisor)
    Abstract
    In the first work, the method of direct growth was used to grew MOFs based on cobalt, as electroactive centers, for preparing electrochemical sensors for the determination of glucose. In comparison to most of the electrochemical sensing platforms based on MOFs for determining glucose, which suffer from some disadvantages like time-consuming synthesis procedures and using hazardous organic solvents, the proposed in situ growth method is much faster and no need to toxic organic solvents. Herein, cobalt-based MOFs were grown on the surface of the reduced graphene oxide modified glassy carbon electrode by the direct and rapid conversion of cobalt hydroxide nanosheets intermediates. The... 

    Fabrication of Composite Electrode Materials Based on Bi-Metalic Metal-Organic Frameworks for Designation of Amperometric Non-Enzymatic Glucose Sensors

    , M.Sc. Thesis Sharif University of Technology Ataei Kachouei, Matin (Author) ; Shahrokhian, Saeed (Supervisor)
    Abstract
    In the present study, the method of direct growth was used to grew bi-metalic MOFs based on cobalt and zinc, as electroactive centers, for preparing electrochemical sensors for the determination of glucose. In comparison to most of the electrochemical sensing platforms based on MOFs for determining glucose, which suffer from some disadvantages like time-consuming synthesis procedures and using hazardous organic solvents, the proposed in-situ growth method is much faster and without any need to toxic organic solvents. Herein, cobalt and zinc-based MOFs were grown on the surface of glassy carbon electrode by the direct and rapid conversion of layered double hydroxide nanosheets intermediates.... 

    Investigation of the electrochemical behavior of catechol and 4-methylcatechol in the presence of methyl mercapto thiadiazol as a nucleophile: application to electrochemical synthesis

    , Article Journal of Applied Electrochemistry ; Volume 40, Issue 1 , 2010 , Pages 115-122 ; 0021891X (ISSN) Shahrokhian, S ; Rastgar, S ; Sharif University of Technology
    Abstract
    The present study concerns the electrochemical behavior of catechol and 4-methylcatechol in the presence of 2-mercapto-5-methyl-1,3,4-thiadiazole (MMT) in aqueous medium on the surface of the glassy carbon electrode by means of cyclic voltammetry and controlled-potential coulometry. The oxidation mechanism was deduced from voltammetric and spectrophotometric data. The electro-generation of quinoid intermediates and their subsequent Michael-type reaction with MMT has been investigated as a clean and convenient strategy for the synthesis of corresponding reaction products. In addition, electro-synthesis of Michael addition products has been successfully accomplished by controlled-potential... 

    Silver nanowires immobilized on gold-modified glassy carbon electrode for electrochemical quantification of atorvastatin

    , Article Journal of Electroanalytical Chemistry ; Volume 876 , November , 2020 Naseri, A ; Hormozi Nezhad, M. R ; Shahrokhian, S ; Asadian, E ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    Development of simple yet precise sensing platforms for rapid determination of biological species and drugs is of paramount importance, not only for analysis of pharmaceutical formulations during the production stage, but also in clinical practices and medical diagnosis. In the present research, we report on the electrochemical determination of atorvastatin (ATOR) by using silver nanowires/gold-modified glassy carbon electrode (Ag NWs/Au/GCE). The modified electrode was constructed through a two-step procedure in which narrow silver nanowires synthesized via a polyol method are drop casted on a pre-modified GCE with electrodeposited gold particles. The results of XRD analysis indicated the... 

    Highly sensitive voltammetric determination of lamotrigine at highly oriented pyrolytic graphite electrode

    , Article Bioelectrochemistry ; Volume 84 , 2012 , Pages 38-43 ; 15675394 (ISSN) Saberi, R. S ; Shahrokhian, S ; Sharif University of Technology
    2012
    Abstract
    The electrochemical behavior of lamotrigine (LMT) at the pyrolytic graphite electrode (PGE) is investigated in detail by the means of cyclic voltammetry. During the electrochemical reduction of LMT, an irreversible cathodic peak appeared. Cyclic voltammetric studies indicated that the reduction process has an irreversible and adsorption-like behavior. The observed reduction peak is attributed to a two-electron process referring to the reduction of azo group. The electrode showed an excellent electrochemical activity toward the electro-reduction of LMT, leading to a significant improvement in sensitivity as compared to the glassy carbon electrode. The results of electrochemical impedance... 

    Electrodeposition of Pt-Ru nanoparticles on multi-walled carbon nanotubes: Application in sensitive voltammetric determination of methyldopa

    , Article Electrochimica Acta ; Volume 58, Issue 1 , 2011 , Pages 125-133 ; 00134686 (ISSN) Shahrokhian, S ; Rastgar, S ; Sharif University of Technology
    2011
    Abstract
    A modified glassy carbon electrode, prepared by potentiostatic electrodeposition of platinum-ruthenium nanoparticles (Pt-RuNPs) onto a multi-walled carbon nanotube (MWCNT) layer, offers dramatic improvements in the stability and sensitivity of voltammetric responses toward methyldopa (m-dopa) compared to glassy carbon electrodes individually coated with MWCNT or Pt-RuNPs. The surface morphology and nature of the hybrid film (Pt-RuNPs/MWCNT) deposited on glassy carbon electrodes was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. A remarkable enhancement in the microscopic area of the electrode together... 

    Anodic behavior of clioquinol at a glassy carbon electrode

    , Article Bioelectrochemistry ; Volume 80, Issue 2 , 2011 , Pages 175-181 ; 15675394 (ISSN) Ghalkhani, M ; Fernandes, I. P. G ; Oliveira, S. C. B ; Shahrokhian, S ; Oliveira-Brett, A. M ; Sharif University of Technology
    2011
    Abstract
    Clioquinol is an antifungal, antiprotozoal and an Alzheimer's disease drug with cytotoxic activity toward human cancer cells. The electrochemical behavior of clioquinol and its oxidation product was studied using cyclic, differential pulse and square-wave voltammetry over a wide pH range on a glassy carbon electrode. The results revealed that the oxidation of clioquinol is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism and results in the formation of a main oxidation product, which adsorbs very strongly on the glassy carbon surface. The charge transfer coefficient was calculated as 0.64. The adsorbed... 

    Simultaneous voltammetric determination of tramadol and acetaminophen using carbon nanoparticles modified glassy carbon electrode

    , Article Electrochimica Acta ; Volume 55, Issue 8 , 2010 , Pages 2752-2759 ; 00134686 (ISSN) Ghorbani Bidkorbeh, F ; Shahrokhian, S ; Mohammadi, A ; Dinarvand, R ; Sharif University of Technology
    2010
    Abstract
    A sensitive and selective electrochemical sensor was fabricated via the drop-casting of carbon nanoparticles (CNPs) suspension onto a glassy carbon electrode (GCE). The application of this sensor was investigated in simultaneous determination of acetaminophen (ACE) and tramadol (TRA) drugs in pharmaceutical dosage form and ACE determination in human plasma. In order to study the electrochemical behaviors of the drugs, cyclic and differential pulse voltammetric studies of ACE and TRA were carried out at the surfaces of the modified GCE (MGCE) and the bare GCE. The dependence of peak currents and potentials on pH, concentration and the potential scan rate were investigated for these compounds... 

    Design and Fabrication of Advanced Electrode Materials Based on Metal-organic Frameworks and Double Layered Hydroxides Using Hollow Copper Hydroxide Nanotubes Scaffold; Application to Nonenzymatic Glucose Sensor

    , M.Sc. Thesis Sharif University of Technology Khaki Sanati, Elnaz (Author) ; Shahrokhian, Saeed (Supervisor)
    Abstract
    One of the remarkable subject in advanced electrochemistry is, design and architecting new advanced materials with new electrochemical capabilities. One of the notable capabilities is electrocatalysis. Extensive researches are carrying out into the design and preparation of electrocatalyst materials to take advantage of these materials in fabrication of electrochemical sensors and storage/conversion devices. In this field nonoporous materials attracted a lot of attentions due to their unique features. In order to make use of the nanoporous materials as the electrocatalysts, these materials must be fabricated into continuous supported thin films on the electrode surface, which is the... 

    Preparation of Nanocomposites Consisting of Nickel Oxide Nanostructures Grown on Hollow Carbon Nanospheres and Evaluation of their Ability for Electrooxidation of Hydrazine Hydrate

    , M.Sc. Thesis Sharif University of Technology Taghaddosi, Sanaz (Author) ; Shahrokhian Dehkordi, Saeed (Supervisor)
    Abstract
    In the present work, nanocomposites consisting of nickel oxide nanostructures and a hollow carbon substrate were used to modify a glassy carbon electrode's surface for the electrooxidation of hydrazine hydrate. For this purpose, hollow carbon nanospheres were first synthesized using aniline and pyrrole copolymerization process without any template needing. The hollow carbon nanospheres prepared by this method have outstanding features such as high specific surface area and good stability. On the other hand, they did not require toxic and environmentally harmful solvents to remove the template. In this study, after preparing hollow carbon nanospheres as a suitable substrate, different...