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Total 33 records

    A novel photometric glucose biosensor based on decolorizing of silver nanoparticles

    , Article Sensors and Actuators, B: Chemical ; Volume 158, Issue 1 , November , 2011 , Pages 185-189 ; 09254005 (ISSN) Tashkhourian, J ; Hormozi Nezhad, M. R ; Khodaveisi, J ; Dashti, R ; Sharif University of Technology
    2011
    Abstract
    A novel glucose biosensor based on chromophore (silver nanoparticles) decolorizing for the photometric determination of glucose was developed. Silver nanoparticles are directly synthesized in the sol-gel matrix by a one-step method based on the reduction of the inorganic precursor AgNO3 and were used for the preparation, characterization and calibration of a highly sensitive and cost-effective localized surface plasmon resonance-based glucose biosensor. In the presence of glucose oxidase (GOx) and due to the enzyme-substrate (glucose) reaction, H2O2 was produced and silver nanoparticles in the sol-gel glass have the ability for the decomposition of hydrogen peroxide. Due to the degradation... 

    Multi sensing grasper for minimally invasive surgery

    , Article IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM, 3 July 2011 through 7 July 2011, Budapest ; July , 2011 , Pages 344-349 ; 9781457708381 (ISBN) Fattahi, S. J ; Zabihollah, A ; Adldoost, H ; Sharif University of Technology
    2011
    Abstract
    In the present work, a multi sensing grasper has been developed for minimally invasive surgery with embedded ZnO piezoelectric and Fiber Bragg Grating sensors. In this model, a sensing patch equipped with three FBG sensors to sense the temperature in rage of 800 n.m and two separated FBG in range of 1550 m.m to detect the displacement in x and y directions. ZnO piezoelectric is highly sensitive to time and provides a good resistance to temperature. Therefore, this sensor is used for measuring the rate of strain and creep coefficient. A finite element approach based on the viscous material theory and plane displacement theory of anisotropic materials has been utilized to obtain the compliance... 

    Carbon-Pt nanoparticles modified TiO 2 nanotubes for simultaneous detection of dopamine and uric acid

    , Article Journal of Nanoscience and Nanotechnology ; Volume 11, Issue 8 , 2011 , Pages 6668-6675 ; 15334880 (ISSN) Mahshid, S ; Luo, S ; Yang, L ; Mahshid, S. S ; Askari, M ; Dolati, A ; Cai, Q ; Sharif University of Technology
    Abstract
    The present work describes sensing application of modified TiO 2 nanotubes having carbon-Pt nanoparticles for simultaneous detection of dopamine and uric acid. The TiO 2 nanotubes electrode was prepared using anodizing method, followed by electrodeposition of Pt nanoparticles onto the tubes. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. The C-Pt-TiO 2 nanotubes modified electrode was characterized by cyclic voltam-metry and differential pulse voltammetry methods. The modified electrode displayed high sensitivity towards the oxidation of dopamine and uric acid in a phosphate buffer solution (pH 7.00). The electro-oxidation currents... 

    Application of pyrolytic graphite modified with nano-diamond/graphite film for simultaneous voltammetric determination of epinephrine and uric acid in the presence of ascorbic acid

    , Article Electrochimica Acta ; Volume 55, Issue 28 , 2010 , Pages 9090-9096 ; 00134686 (ISSN) Shahrokhian, S ; Khafaji, M ; Sharif University of Technology
    2010
    Abstract
    A novel modified pyrolytic graphite electrode with nano-diamond/graphite was fabricated. The electrochemical response characteristics of the modified electrode toward the epinephrine (EN) and uric acid (UA) were studied by means of cyclic and linear sweep voltammetry. The structural morphology and thickness of the film was characterized by SEM technique. The prepared electrode showed an excellent catalytic activity in the electrochemical oxidation of EN and UA, leading to remarkable enhancements in the corresponding peak currents and lowering the peak potentials. The prepared modified electrode acts as a highly sensitive sensor for simultaneous determination of EN and UA in the presence of... 

    Simultaneous voltammetric determination of ascorbic acid, acetaminophen and isoniazid using thionine immobilized multi-walled carbon nanotube modified carbon paste electrode

    , Article Electrochimica Acta ; Volume 55, Issue 3 , 2010 , Pages 666-672 ; 00134686 (ISSN) Shahrokhian, S ; Asadian, E ; Sharif University of Technology
    2010
    Abstract
    A carbon paste electrode (CPE) modified with thionine immobilized on multi-walled carbon nanotube (MWCNT), was prepared for simultaneous determination of ascorbic acid (AA) and acetaminophen (AC) in the presence of isoniazid (INZ). The electrochemical response characteristics of the modified electrode toward AA, AC and INZ were investigated by cyclic and differential pulse voltammetry (CV and DPV). The results showed an efficient catalytic role for the electro-oxidation of AA and AC, leading to a remarkable peak resolution (∼303 mV) for two compounds. On the other hand, the presence of INZ, which is considered as important drug interference for AC, does not affect the voltammetric responses... 

    Application of carbon-paste electrode modified with iron phthalocyanine for voltammetric determination of epinephrine in the presence of ascorbic acid and uric acid

    , Article Sensors and Actuators, B: Chemical ; Volume 137, Issue 2 , 2009 , Pages 669-675 ; 09254005 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Amini, M. K ; Sharif University of Technology
    2009
    Abstract
    A carbon-paste electrode (CPE) modified with iron(II) phthalocyanine was used for the sensitive voltammetric determination of epinephrine (EN). The electrochemical response characteristics of the modified electrode toward EN, ascorbic acid (AA) and uric acid (UA) were investigated by cyclic and differential pulse voltammetry (CV and DPV). The results show an efficient catalytic activity of the electrode for the electro-oxidation of EN, which leads to improvement of reversibility of the electrode response and lowering its overpotential by more than 100 mV. The effect of pH and potential sweep rate on the mechanism of the electrode process was investigated. The modified electrode exhibits an... 

    Electrocatalytic oxidation and nanomolar determination of guanine at the surface of a molybdenum (VI) complex-TiO2 nanoparticle modified carbon paste electrode

    , Article Journal of Electroanalytical Chemistry ; Volume 624, Issue 1-2 , 2008 , Pages 73-78 ; 15726657 (ISSN) Mazloum Ardakani, M ; Taleat, Z ; Beitollahi, H ; Salavati Niasari, M ; Mirjalili, B. B. F ; Taghavinia, N ; Sharif University of Technology
    Elsevier  2008
    Abstract
    A modified carbon paste electrode was prepared by incorporating TiO2 nanoparticles with bis[bis(salicylidene-1,4-phenylenediamine)molybdenum(VI)]. A mixture of fine graphite powder with 4 wt% of TiO2 nanoparticles was applied for the preparation of the carbon paste (by dispersing in paraffin) and finally modified with a molybdenum (VI) complex. The electrocatalytic oxidation of guanine (G) was investigated on the surface of the molybdenum (VI) complex-TiO2 nanoparticle modified carbon paste electrode (MCTNMCPE) using cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry (CHA) and chronocoloumetry (CHC). Using the modified electrode, the kinetics of G... 

    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
    Abstract
    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,... 

    Amperometric sulfide detection using Coprinus cinereus peroxidase immobilized on screen printed electrode in an enzyme inhibition based biosensor

    , Article Biosensors and Bioelectronics ; Volume 35, Issue 1 , 2012 , Pages 297-301 ; 09565663 (ISSN) Savizi, I. S. P ; Kariminia, H. R ; Ghadiri, M ; Roosta Azad, R ; Sharif University of Technology
    2012
    Abstract
    In the present work, an amperometric inhibition biosensor for the determination of sulfide has been fabricated by immobilizing Coprinus cinereus peroxidase (CIP) on the surface of screen printed electrode (SPE). Chitosan/acrylamide was applied for immobilization of peroxidase on the working electrode. The amperometric measurement was performed at an applied potential of -150. mV versus Ag/AgCl with a scan rate of 100. mV in the presence of hydroquinone as electron mediator and 0.1. M phosphate buffer solution of pH 6.5. The variables influencing the performance of sensor including the amount of substrate, mediator concentration and electrolyte pH were optimized. The determination of sulfide... 

    In situ solid-phase microextraction and post on-fiber derivatization combined with gas chromatography-mass spectrometry for determination of phenol in occupational air

    , Article Analytica Chimica Acta ; Volume 742 , 2012 , Pages 17-21 ; 00032670 (ISSN) Es haghi, A ; Baghernejad, M ; Bagheri, H ; Sharif University of Technology
    Elsevier  2012
    Abstract
    A method based on solid-phase microextraction (SPME) followed by on-fiber derivatization and gas chromatography-mass spectrometry detection (GC-MS) for determination of phenol in air was developed. Three different types of SPME fibers, polar and non-polar poly(dimethylsiloxane) (PDMS) and polyethylene glycol (PEG) were synthesized using sol-gel technology and their feasibility to the sampling of phenol were investigated. Different derivatization reagents for post on-fiber derivatization of phenol were studied. Important parameters influencing the extraction and derivatization process such as type of fiber coating, type and volume of derivatizing reagent, derivatization time and temperature,... 

    Mediator-less highly sensitive voltammetric detection of glutamate using glutamate dehydrogenase/vertically aligned CNTs grown on silicon substrate

    , Article Biosensors and Bioelectronics ; Volume 31, Issue 1 , 2012 , Pages 110-115 ; 09565663 (ISSN) Gholizadeh, A ; Shahrokhian, S ; Iraji zad, A ; Mohajerzadeh, S ; Vosoughi, M ; Darbari, S ; Sanaee, Z ; Sharif University of Technology
    Abstract
    A sensitive glutamate biosensor is prepared based on glutamate dehydrogenase/vertically aligned carbon nanotubes (GLDH, VACNTs). Vertically aligned carbon nanotubes were grown on a silicon substrate by direct current plasma enhanced chemical vapor deposition (DC-PECVD) method. The electrochemical behavior of the synthesized VACNTs was investigated by cyclic voltammetry and electrochemical impedance spectroscopic methods. Glutamate dehydrogenase covalently attached on tip of VACNTs. The electrochemical performance of the electrode for detection of glutamate was investigated by cyclic and differential pulse voltammetry. Differential pulse voltammetric determinations of glutamate are performed... 

    Voltammetric studies of sumatriptan on the surface of pyrolytic graphite electrode modified with multi-walled carbon nanotubes decorated with silver nanoparticles

    , Article Talanta ; Volume 80, Issue 1 , 2009 , Pages 31-38 ; 00399140 (ISSN) Ghalkhani, M ; Shahrokhian, S ; Ghorbani Bidkorbeh, F ; Sharif University of Technology
    2009
    Abstract
    Multi-walled carbon nanotube decorated with silver nanoparticles (AgNPs-MWCNT) is used as an effective strategy for modification of the surface of pyrolytic graphite electrode (PGE). This modification procedure improved colloidal dispersion of the decorated MWCNTs in water, affording uniform and stable thin films for altering the surface properties of the working electrode. Robust electrode for sensing applications is obtained in a simple solvent evaporation process. The electrochemical behavior of sumatriptan (Sum) at the bare PGE and AgNPs-MWCNT modified PGE is investigated. The results indicate that the AgNPs-MWCNT modified PGE significantly enhanced the oxidation peak current of Sum. 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
    2009
    Abstract
    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....