Search for: glassy-carbon-electrodes
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    Fast and ultra-sensitive voltammetric detection of lead ions by two-dimensional graphitic carbon nitride (g-C3N4) nanolayers as glassy carbon electrode modifier

    , Article Measurement: Journal of the International Measurement Confederation ; Volume 134 , 2019 , Pages 679-687 ; 02632241 (ISSN) Hatamie, A ; Jalilian, P ; Rezvani, E ; Kakavand, A ; Simchi, A ; Sharif University of Technology
    Elsevier B.V  2019
    Recently, graphitic carbon nitride (g-C3N4) has attracted great interest for photo(electro)chemical applications such as sensing, solar energy exploitation, photocatalysis, and hydrogen generation. This paper presents the potential application and benefits of g-C3N4 nanolayers as a green and highly efficient electrode modifier for the detection of trace lead ions in drinking water and urban dust samples. Carbon nitride nanosheets with a thickness of ∼6 A° and lateral of 100–150 nm were prepared through high-temperature polymerization of melamine followed by sonication-assisted liquid exfoliation. A glassy carbon electrode (GCE) was modified by a thin layer of g-C3N4 through drop casting and... 

    Evaluation of molecular imprinted polymerized methylene blue/aptamer as a novel hybrid receptor for cardiac troponin I (cTnI) detection at glassy carbon electrodes modified with new biosynthesized ZnONPs

    , Article Sensors and Actuators, B: Chemical ; Volume 320 , 1 October , 2020 Mokhtari, Z ; Khajehsharifi, H ; Hashemnia, S ; Solati, Z ; Azimpanah, R ; Shahrokhian, S ; Sharif University of Technology
    Elsevier B.V  2020
    In this research, a novel, rapid, and non-immune electrochemical method was used to detect cardiac troponin I (cTnI) using a double recognition approach. Amine terminus cTnI aptamers immobilized on COOH-ZnO nanoparticles (COOH-ZnONPs) modified GCE surface were applied to capture cTnI for imprinting recognition. The COOH-ZnONPs were synthesized in a biological manner. Then, the methylene blue (MB) monomers were electro-polymerized around the cTnI-aptamer complexes. Following the removal of cTnI, cavities were constructed and converted to a new aptamer and molecular imprinted polymer (MIP) hybrid receptor (aptamer/MIP/ZnONPs). FT-IR spectra, SEM images, XRD patterns, and electrochemical... 

    Sensitive voltammetric detection of melatonin in pharmaceutical products by highly conductive porous graphene-gold composites

    , Article ACS Sustainable Chemistry and Engineering ; 2020 Rahmati, R ; Hemmati, A ; Mohammadi, R ; Hatamie, A ; Tamjid, E ; Simchi, A ; Sharif University of Technology
    American Chemical Society  2020
    This work presents a novel melatonin sensor based on unfunctionalized macroporous graphene networks decorated with gold nanoparticles for the differential pulse voltammetric detection of melatonin in pharmaceutical products. Highly porous graphene structures were prepared by metallic template-assisted chemical vapor deposition, and their active surface area and electrocatalytic activity were improved by electrochemical deposition of gold nanoparticles (50-250 nm) on their struts. The graphene-gold electrodes present a highly sensitive performance toward electro-oxidation of melatonin with a wide linear range of 0.05-50 μM, a low detection limit of 0.0082 μM (3σ/m), and a significant... 

    Kinetic interpretation of a negative time constant impedance of glucose electrooxidation

    , Article Journal of Physical Chemistry B ; Volume 112, Issue 49 , 2008 , Pages 15933-15940 ; 15206106 (ISSN) Danaee, I ; Jafarian, M ; Forouzandeh, F ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    American Chemical Society  2008
    Nickel - copper alloy modified glassy carbon electrodes (GC/NiCu) prepared by galvanostatic deposition were used for the electrocatalytic oxidation of glucose in alkaline solutions. The electro-oxidation of glucose in a 1 M NaOH solution at different concentration of glucose was studied by the method of ac-impedance spectroscopy. The impedance behavior show different patterns, capacitive, and inductive loops and negative resistances, at different applied anodic potential. The influence of the electrode potential on the impedance pattern is studied and a quantitative explanation for the impedance behavior of glucose oxidation is put forward by a proposed mathematical model. At potentials... 

    Ionic liquid/graphene oxide as a nanocomposite for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase

    , Article Journal of Solid State Electrochemistry ; Volume 17, Issue 1 , January , 2013 , Pages 183-189 ; 14328488 (ISSN) Tasviri, M ; Ghasemi, S ; Ghourchian, H ; Gholami, M. R ; Sharif University of Technology
    By combination of 1-ethyl-3-methyl immidazolium ethyl sulfate as a typical room temperature ionic liquid (IL) and graphene oxide (GO) nanosheets, a nanocomposite was introduced for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase (GOx). The enzyme on the IL-GO-modified glassy carbon electrode exhibited a quasireversible cyclic voltammogram corresponding to the flavine adenine dinucleotide/FADH2 redox prosthetic group of GOx. At the scan rate of 100 mV s-1, the enzyme showed a peak-to-peak potential separation of 82 mV and the formal potential of -463 mV (vs Ag/AgCl in 0.1 M phosphate buffer solution, pH 7.0). The kinetic parameters of the charge transfer... 

    Glassy carbon electrode modified with a bilayer of multi-walled carbon nanotube and polypyrrole doped with new coccine: Application to the sensitive electrochemical determination of Sumatriptan

    , Article Electrochimica Acta ; Volume 56, Issue 27 , November , 2011 , Pages 10032-10038 ; 00134686 (ISSN) Shahrokhian, S ; Kamalzadeh, Z ; Saberi, R. S ; Sharif University of Technology
    A promising electrochemical sensor was developed based on a layer by layer process by electro-polymerization of pyrrole in the presence of new coccine (NC) as dopant anion on the surface of the multi-walled carbon nanotubes (MWCNTs) pre-coated glassy carbon electrode (GCE). The modified electrode was used as a new and sensitive electrochemical sensor for voltammetric determination of sumatriptan (SUM). The electrochemical behavior of SUM was investigated on the surface of the modified electrode using linear sweep voltammetry (LSV). The results showed a remarkable increase (∼12 times) in the anodic peak current of SUM in comparison to the bare GCE. The effect of experimental variables such... 

    A novel enzyme based biosensor for catechol detection in water samples using artificial neural network

    , Article Biochemical Engineering Journal ; Volume 128 , 2017 , Pages 1-11 ; 1369703X (ISSN) Maleki, N ; Kashanian, S ; Maleki, E ; Nazari, M ; Sharif University of Technology
    Elsevier B.V  2017
    Biosensors could be used as digital devices to measure the sample infield. Consequently, computational programming along with experimental achievements are required. In this study, a novel biosensor/artificial neural network (ANN) integrated system was developed. Poly (3,4-ethylenedioxy-thiophene)(PEDOT), graphene oxide nano-sheets (GONs) and laccase (Lac) were used to construct a biosensor. The simple and one-pot process was accomplished by electropolymerizing 3,4-ethylenedioxy-thiophene (EDOT) along with GONs and Lac as dopants on glassy carbon electrode. Scanning electron microscopy (SEM) and electrochemical characterization were conducted to confirm successful enzyme entrapment. The... 

    Nanocomposite with promoted electrocatalytic behavior based on bimetallic pd-ni nanoparticles, manganese dioxide, and reduced graphene oxide for efficient electrooxidation of ethanol

    , Article Journal of Physical Chemistry C ; Volume 122, Issue 18 , 2018 , Pages 9783-9794 ; 19327447 (ISSN) Rezaee, S ; Shahrokhian, S ; Amini, M. K ; Sharif University of Technology
    American Chemical Society  2018
    In this work, a nanocomposite containing manganese dioxide (MnO2) modified reduced graphene oxide (rGO) supported bimetallic palladium-nickel (Pd-Ni) catalyst is prepared by electrodeposition method. The nanocomposite modifier film is prepared by forming a thin layer of graphene oxide (GO) via drop-casting of GO nanosheet dispersion on glassy carbon electrode (GCE), followed by electrochemical reduction of the film to provide rGO/GCE. Then, a two-step potential procedure is applied to deposit MnO2 nanoparticles on rGO/GCE. At the optimum deposition conditions, MnO2 nanoparticles with a thickness of 30-50 nm homogeneously covered the rGO surface (MnO2/rGO/GCE). Finally, the bimetallic Pd-Ni... 

    Electrocatalytic oxidation of glucose on Ni and NiCu alloy modified glassy carbon electrode

    , Article Journal of Solid State Electrochemistry ; Volume 13, Issue 8 , 2009 , Pages 1171-1179 ; 14328488 (ISSN) Jafarian, M ; Forouzandeh, F ; Danaee, I ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    Nickel and nickel-copper alloy modified glassy carbon electrodes (GC/Ni and GC/NiCu) prepared by galvanostatic deposition were examined for their redox processes and electro-catalytic activities towards the oxidation of glucose in alkaline solutions. The methods of cyclic voltammetry (CV) and chronoamperometry (CA) were employed. The cyclic voltammogram of NiCu alloy demonstrates the formation of β/β crystallographic forms of the nickel oxyhydroxide under prolonged repetitive potential cycling in alkaline solution. It is also observed that the overpotential for O 2 evolution increases for NiCu alloy modified electrode. In CV studies, NiCu alloy modified electrode yields significantly higher... 

    Electrochemical determination of clozapine on MWCNTs/new coccine doped ppy modified GCE: An experimental design approach

    , Article Bioelectrochemistry ; Volume 90 , 2013 , Pages 36-43 ; 15675394 (ISSN) Shahrokhian, S ; Kamalzadeh, Z ; Hamzehloei, A ; Sharif University of Technology
    The electrooxidation of clozapine (CLZ) was studied on the surface of a glassy carbon electrode (GCE) modified with a thin film of multiwalled carbon nanotubes (MWCNTs)/new coccine (NC) doped polypyrrole (PPY) by using linear sweep voltammetry (LSV). The pH of the supporting electrolyte (D), drop size of the cast MWCNTs suspension (E) and accumulation time of CLZ on the surface of modified electrode (F) was considered as effective experimental factors and the oxidation peak current of CLZ was selected as the response. By using factorial-based response-surface methodology, the optimum values of factors were obtained as 5.44, 10 μL and 300 s for D, E and F respectively. Under the optimized... 

    Fabrication of a modified electrode based on Fe3 O4 NPs/MWCNT nanocomposite: Application to simultaneous determination of guanine and adenine in DNA

    , Article Bioelectrochemistry ; Volume 86 , 2012 , Pages 78-86 ; 15675394 (ISSN) Shahrokhian, S ; Rastgar, S ; Amini, M. K ; Adeli, M ; Sharif University of Technology
    Multi-walled carbon nanotubes decorated with Fe 3O 4 nanoparticles (Fe 3O 4NPs/MWCNT) were prepared and used to construct a novel biosensor for the simultaneous detection of adenine and guanine. The direct electro-oxidation of adenine and guanine on the modified electrode were investigated by linear sweep voltammetry. The results indicate a remarkable increase in the oxidation peak currents together with negative shift in the oxidation peak potentials for both adenine and guanine, in comparison to the bare glassy carbon electrode (GCE). The surface morphology and nature of the composite film deposited on GCE were characterized by transmission electron microscopy, atomic force microscopy,... 

    Toward single-DNA electrochemical biosensing by graphene nanowalls

    , Article ACS Nano ; Volume 6, Issue 4 , March , 2012 , Pages 2904-2916 ; 19360851 (ISSN) Akhavan, O ; Ghaderi, E ; Rahighi, R ; Sharif University of Technology
    Graphene oxide nanowalls with extremely sharp edges and preferred vertical orientation were deposited on a graphite electrode by using electrophoretic deposition in an Mg 2+-GO electrolyte. Using differential pulse voltammetry (DPV), reduced graphene nanowalls (RGNWs) were applied for the first time, in developing an ultra-high-resolution electrochemical biosensor for detection of the four bases of DNA (G, A, T, and C) by monitoring the oxidation signals of the individual nucleotide bases. The extremely enhanced electrochemical reactivity of the four free bases of DNA, single-stranded DNA, and double-stranded DNA (dsDNA) at the surface of the RGNW electrode was compared to electrochemical... 

    Electrochemical preparation of over-oxidized polypyrrole/multi-walled carbon nanotube composite on glassy carbon electrode and its application in epinephrine determination

    , Article Electrochimica Acta ; Volume 57, Issue 1 , 2011 , Pages 132-138 ; 00134686 (ISSN) Shahrokhian, S ; Saberi, R. S ; Sharif University of Technology
    A composite film constructed of surfactant doped over-oxidized polypyrrole and multi-walled carbon nanotube was prepared on the surface of glassy carbon electrode by the electro-polymerization method. Surface characterization of the modified electrode was performed by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectrometry. The investigations have been proved that the over-oxidation of the modifier film resulted in a porous thin layer that improves the interlayer diffusion mechanism for the electroactive species. On the other hand, the negative charge density on the surface of the electrode excludes the negative analytes (e.g. ascorbate and Fe(CN)63?/4?)... 

    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
    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... 

    Electrochemical determination of naltrexone on the surface of glassy carbon electrode modified with Nafion-doped carbon nanoparticles: Application to determinations in pharmaceutical and clinical preparations

    , Article Journal of Electroanalytical Chemistry ; Volume 638, Issue 2 , 2010 , Pages 212-217 ; 15726657 (ISSN) Ghorbani Bidkorbeh, F ; Shahrokhian, S ; Mohammadi, A ; Dinarvand, R ; Sharif University of Technology
    A new sensitive and selective electrochemical sensor was developed for determination of naltrexone (NAL) in pharmaceutical dosage form and human plasma. Naltrexone is an opioid antagonist which is commonly used for the treatment of narcotic addiction and alcohol dependence. A voltammetric study of naltrexone has been carried out at the surface of glassy carbon electrode (GCE) modified with Nafion-doped carbon nanoparticles (CNPs). The electrochemical oxidation of naltrexone was investigated by cyclic and differential pulse voltammetric techniques. The dependence of peak currents and potentials on pH, concentration and the potential scan rate was investigated. The electrode characterization... 

    Highly sensitive nonenzymetic glucose sensing platform based on MOF-derived NiCo LDH nanosheets/graphene nanoribbons composite

    , Article Journal of Electroanalytical Chemistry ; Volume 808 , 2018 , Pages 114-123 ; 15726657 (ISSN) Asadian, E ; Shahrokhian, S ; Iraji Zad, A ; Sharif University of Technology
    Elsevier B.V  2018
    Herein, a novel sensing platform based on NiCo layered double hydroxide (LDH) nanosheets/graphene nanoribbons (GNRs) modified glassy carbon electrode is presented for sensitive non-enzymetic determination of glucose. In the first step, nanoflower-like NiCo LDH nanosheets were grown on the surface of ZIF-67 dodecahedron nanocrystals which used as sacrificial template and were further characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD) and FTIR. In the next step, in order to fabricate a mechanically stable modified electrode, the as-prepared nanosheets were mixed with... 

    Electrochemical determination of l-dopa in the presence of ascorbic acid on the surface of the glassy carbon electrode modified by a bilayer of multi-walled carbon nanotube and poly-pyrrole doped with tiron

    , Article Journal of Electroanalytical Chemistry ; Volume 636, Issue 1-2 , 2009 , Pages 40-46 ; 15726657 (ISSN) Shahrokhian, S ; Asadian, E ; Sharif University of Technology
    Elsevier  2009
    There are high attractions in the development of conducting polymer (CP) coatings to improve the electrochemical properties and biocompatibility of electrodes in the area of biosensors. A new type of the modified electrodes is prepared in a layer-by-layer process by using multi-walled carbon nanotube (MWCNT) and poly-pyrrole. In this procedure, the glassy carbon electrode is casted by a drop suspension of MWCNT, which leads to form a thin film of nanotube on its surface. In the second step, electrochemical polymerization of pyrrole in the presence of tiron (used as doping anion) is performed on the surface of the MWCNT pre-coated electrode. The modification procedure led to fabrication of a... 

    Multi-walled carbon nanotubes with immobilised cobalt nanoparticle for modification of glassy carbon electrode: Application to sensitive voltammetric determination of thioridazine

    , Article Biosensors and Bioelectronics ; Volume 24, Issue 11 , 2009 , Pages 3235-3241 ; 09565663 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Adeli, M ; Amini, M. K ; Sharif University of Technology
    Multi-walled carbon nanotubes (MWCNTs) were immobilised with cobalt nanoparticles and analyzed by transmission electron microscopy. This modification procedure substantially improved colloidal dispersion of the immobilised MWCNTs in water and organic solvents, yielding uniform and stable thin films for modification of the glassy carbon electrode surface. The modified electrode showed an efficient catalytic role for the electrochemical oxidation of thioridazine (TR), leading to remarkable decrease in its oxidation overpotential of approximately 100 mV and enhancement of the kinetics of the electrode reaction, which can be confirmed by increasing in the peak current and sharpness of the peak.... 

    Design and fabrication of an electrochemical aptasensor using Au nanoparticles/carbon nanoparticles/cellulose nanofibers nanocomposite for rapid and sensitive detection of Staphylococcus aureus

    , Article Bioelectrochemistry ; Volume 123 , 2018 , Pages 70-76 ; 15675394 (ISSN) Ranjbar, S ; Shahrokhian, S ; Sharif University of Technology
    Elsevier B.V  2018
    Since that pathogenic bacteria are major threats to human health, this paper describes the fabrication of an effective and durable sensing platform based on gold nanoparticles/carbon nanoparticles/cellulose nanofibers nanocomposite (AuNPs/CNPs/CNFs) at the surface of glassy carbon electrode for sensitive and selective detection of Staphylococcus aureus (S. aureus). The AuNPs/CNPs/CNFs nanocomposite with the high surface area, excellent conductivity, and good biocompatibility was used for self-assembled of the thiolated specific S. aureus aptamer as a sensing element. The surface morphology of AuNPs/CNPs/CNFs nanocomposite was characterized with field emission scanning electron microscopy...