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    Two nanostructured polymers: Polyaniline nanofibers and new linear-dendritic matrix of poly(citric acid)-block-poly(ethylene glycol) copolymers for environmental monitoring in novel biosensors

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 62, Issue 7 , Jul , 2013 , Pages 377-383 ; 00914037 (ISSN) Shamloo, A ; Vossoughi, M ; Alemzadeh, I ; Naeini, A. T ; Darvish, M ; Sharif University of Technology
    2013
    Abstract
    In this work two phenol biosensors, one based on polyaniline nanofibers (PNFs) and the other based on the newly created and introduced linear-dendritic matrix of poly(citric acid)-block-poly(ethylene glycol) copolymers (PCA-PEG-PCA), were chemically modified with horseradish peroxidase (HRP) enzyme. These phenol biosensors showed an oxidation peak at 0.55 V. The amperometric response for biosensors based on PNFs showed a linear response range from 2.5 × 10-6 to 2.5 × 10-5 mol/L, with a detection limit of 2.5 M phenol. Also, the amperometric response for a biosensor based on PCA-PEG-PCA showed a linear response range from 2.5 × 10-6 to 4 × 10-5 mol/L, with a detection limit of 1.5 M phenol  

    Horseradish peroxidase immobilization on amine functionalized carbon nanotubes: Direct electrochemistry and bioelectrocatalysis

    , Article Progress in Reaction Kinetics and Mechanism ; Volume 37, Issue 2 , May , 2012 , Pages 161-172 ; 14686783 (ISSN) Tasviri, M ; Ghourchian, H ; Gholami, M. R ; Rafiee Pour, H. A ; Sharif University of Technology
    2012
    Abstract
    Horseradish peroxidase (HRP) was successfully immobilized on amine functionalized TiO 2-coated multiwalled carbon nanotubes (NH 2-TiO 2-CNTs) by a convenient and efficient method. Electrochemical impedance spectroscopy, cyclic voltammetry and amperometry were applied to characterize the HRP/NH 2-TiO 2-CNT nano-composite. These techniques showed that the NH 2-TiO 2-CNTs greatly enhance the electron transfer between HRP and the modified electrode. Owing to the redox reaction of the electroactive centre of HRP, the HRP/NH 2-TiO 2-CNTs modified electrode exhibited a pair of quasi-reversible peaks with a peak-to-peak separation (ΔE p) of 70.6mV and a formal potential (E 0′) of -367.65mV (versus... 

    Development of a novel method for determination of mercury based on its inhibitory effect on horseradish peroxidase activity followed by monitoring the surface plasmon resonance peak of gold nanoparticles

    , Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 153 , 2016 , Pages 709-713 ; 13861425 (ISSN) Khodaveisi, J ; Haji Shabani, A. M ; Dadfarnia, S ; Rohani Moghadam, M. R ; Hormozi Nezhad, M. R ; Sharif University of Technology
    Elsevier 
    Abstract
    A highly sensitive and simple indirect spectrophotometric method has been developed for the determination of trace amounts of inorganic mercury (Hg2 +) in aqueous media. The method is based on the inhibitory effect of Hg2 + on the activity of horseradish peroxidase (HRP) in the oxidation of ascorbic acid by hydrogen peroxide followed by the reduction of Au3 + to Au-NPs by unreacted ascorbic acid and the measurement of the absorbance of localized surface plasmon resonance (LSPR) peak of gold nanoparticles (at 530 nm) which is directly proportional to the concentration of Hg2 +. Under the optimum conditions, the calibration curve was linear in the concentration range of 1-220 ng mL- 1. Limits...