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Analytical & Bioanalytical Electrochemistry - Volume:8 Issue: 6, Sep 2016

Analytical & Bioanalytical Electrochemistry
Volume:8 Issue: 6, Sep 2016

  • تاریخ انتشار: 1395/08/19
  • تعداد عناوین: 10
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  • Fatemeh Ahour*, Mohammad Hossein Pournaghi, Azar, Mohammad Kazem Ahsani, Mohammad Saeid Hejazi Pages 661-674
    Several studies show that acute infections with hepatitis C virus (HCV) frequently progresses to chronic diseases, eventually can lead to liver cirrhosis and hepatocellular carcinoma. Thus, development of simple and reliable HCV detection methods is in demand. The present paper describes electrochemical detection of polymerase chain reaction (PCR)-amplified Core/E1 encoding cDNA corresponding to hepatitis C virus (573 bp size) directly in double stranded form without any purification, pre-treatment and the need for denaturation of the target. The biosensor relies on the hybridization between self-assembled cysteine conjugated 20-mer peptide nucleic acid (PNA) oligomer probe and complementary ds-PCR products to form PNA-ds-PCR hybrid. The extent of hybridization between the probe and target sequences was determined by using differential pulse voltammetric signal of methylene blue (MB) as the hybridization indicator. In order to improve biosensing performance, the effect of various factors was investigated. The selectivity of the sensor was assessed with two different non-complementary PCR products (ds-PCRnon-COM). Diagnostic performance of the biosensor is described and the detection limit is found to be 1.58 ppm. The reliability of the electrochemical biosensing results was verified by electrophoresis of the PCR products.
    Keywords: DNA biosensor_Electrochemical methods_Hepatitis C virus_Polymerase chain reaction_peptide nucleic acid
  • Mohammad Mazloum, Ardakani*, Rezvan Arazi Pages 675-690
    In this present work, we prepared a carbon paste modified electrode with 9,10-dihydroxy-7-methoxy-6H-benzofuro[3,2-c]chromen-6-one (DMC) and titanium dioxide nanofiber composite (DMC/NF/CP) as a electrochemical sensor for electrochemically sensitive and selective detection of tryptophan (Trp.) in the presence of penicillamine (PA) and folic acid (FA). The modified CPE was successfully used to determine the concentrations of Trp., PA and FA in real samples. The electron transfer rate constant, ks, and transfer coefficient, α, were calculated to be 1.88 s−1 and 0.6 respectively, by cyclic voltammetry measurements. The catalytic peak current obtained from differential pulse voltammetry (DPV was linearly towards the Trp. concentration in the range of 1.0-900.0 μM. The detection limit (3σ) for Trp. was 0.103 μM with a sensitivity of 0.128 μA μM-1.
    Keywords: Electrochemical sensor, Nanofiber, Tryptophan, Penicillamine, Folic acid
  • Gamal A. Saleh, Hassan F. Askal, Ibrahim H. Refaat, Fatma A. M. Abdel, Aal* Pages 691-716
    Recent clinical and pre-clinical data demonstrate that adjuvant antimicrobial therapy is beneficial in cancer treatment. For the first time, an electrochemical method was proposed for the simultaneous determination of acyclovir (ACV) and methotrexate (MTX) at activated or electropretreated pencil graphite electrode (EPPEG). Their simultaneous determination was achieved by cyclic voltammetry (CV) and adsorptive square wave voltammetry (AdSWV) techniques. The proposed sensor has a wide linear range of 2×10 -7 to 1.4×10 -6 M for MTX and 5×10 -7 to 3×10 -6 M for ACV. The limits of detection (LOD) values were found 1.13×10-8 M and 6.07×10-8 M for MTX and ACV, respectively. The proposed method was applied in their pharmaceutical formulations and human plasma. In addition the proposed method could be applied in pharmaceutical laboratories and quality control analysis in the near future.
    Keywords: Acyclovir, Methotrexate, Adsorptive square wave voltammetry, Electropretreated pencil graphite electrode, Human plasma
  • Parviz Mohamadian Samim, Arash Fattah, Alhosseini* Pages 717-731
    In this work, the effect of cyclic potentiodynamic passivation (CPP) on the electrochemical behavior of AISI 304 stainless steel in an alkaline medium simulating the concrete pore (0.1 M NaOH.1 M KOH) solution was investigated. CPP was very effective to enhance the open circuit potential of the sample. It was shown that the open circuit potential of the sample became 200 mV nobler by applying 100 cycles of voltammetry. Mott–Schottky analysis revealed that although CPP did not change the semiconducting character of the passive film, it reduced the charge carrier densities within the passive film. After applying 100 cycles of voltammetry, the donor density decreased from the initial value of 1.152×1021 cm-3 to 0.649×1021 cm-3, and the acceptor density decreased from the initial value of 0.953×1021cm-3 to 0.574×1021 cm-3 Electrochemical impedance spectroscopy measurements showed that the passive film resistance of AISI 304 stainless steel was 75.6 kΩ.cm2 before applying CPP method, while it was increased to 7735.7 kΩ.cm2 after applying 100 cycles of voltammetry. All electrochemical tests showed that the electrochemical behavior of AISI 304 stainless steel was improved under the influence of CPP method, mainly due to the formation of thicker and also less defective passive film.
    Keywords: Cyclic potentiodynamic passivation, Stainless steel, Electrochemical impedance spectroscopy, Mott, Schottky analysis
  • Hadiseh Salimi, Hadi Beitollahi* Pages 732-740
    A convenient, low cost, and sensitive electrochemical method, based on a glassy carbon electrode modified with graphene/ZnO nanocomposite is described for determination of vitamin B6. The modified electrode exhibited good electrochemical properties toward the oxidation of vitamin B6. The diffusion coefficient (D=1.89×10-5 cm2 s-1), and the kinetic parameter such as the electron transfer coefficient, (α=0.53) of vitamin B6 oxidation at the surface of modified electrode was determined using electrochemical approaches. The anodic peak currents of vitamin B6 were found to be linear in the concentration range of 1.0–16000.0 μM with the detection limit of 7.2×10-7 M.
    Keywords: Vitamin B6, Graphene, ZnO nanocomposite, Glassy carbon electrode, Voltammetry
  • Ali Rudbaraki, Mohammad A. Khalilzadeh* Pages 741-748
    A carbon paste electrode modified with NiO nanoparticles (CPE-M-NiO/NPs) was fabricated and used as a high performance sensor for nitrite (NT). CPE-M-NiO/NPs was prepared by mixing NiO/NPs, graphite powder and liquid paraffin together. The CPE-M-NiO/NPs showed electrocatalytic activity to the electro-oxidation of NT, and an irreversible oxidation peak appeared at 0.90 V with improved peak current. The linear response range was found to be 0.8–1100 μM. Detection limit (3σ) of NT was found to be 0.3 μM by square wave voltammetry (SWV) method. The CPE-M-NiO/NPs was successfully applied for the determination of NT in food samples.
    Keywords: Nitrite analysis, Modified electrode, NiO nanoparticles, Voltammetry
  • Volodymyr V. Tkach, Yana G. Ivanushkos., Iacute, Lvio C. De Oliveira, Genilson R. Da Silva, Reza Ojani, Petro I. Yagodynets Pages 749-760
    The possibility of electrochemical oxidation of omeprazole on CoO(OH) for electrochemical analysis in vitro and in vivo has been evaluated by theoretical means. The corresponding mathematical model was analyzed by means of linear stability theory and bifurcation analysis. It was demonstrated that cobalt (III) oxy-hydroxide may be used as an electrode modifier for the electrochemical detection of omeprazole in pharmaceutical samples. The possibility for electrochemical instabilities has also been evaluated.
    Keywords: Omeprazole, Chemically modified electrodes, Cobalt (III) oxy, hydroxide, electrochemical pharmaceutical analysis, Stable steady, state
  • Maulidiyah*, Diono Saputro Tribawono, Dwiprayogo Wibowo, Muhammad Nurdin* Pages 761-776
    The new method of electrochemical degradation of Amino Acid by flow system using TiO2/Ti electrode had been carried out. The electrode was synthesized by anodic oxidation processes and analyzed its electrochemical profile degradation. The development of the flow system for determining the profile and photocurrent response of amino acid, i.e phenylalanine, glycine, and glutamine were performed by using Linear Sweep Voltammetry (LSV), Multi-Pulse Amperometry (MPA) and Cyclic Voltammetry (CV) techniques. The optimum pH measurement of phenylalanine, glycine, and glutamine were 8.54, 7.80 and 8.53, respectively. Data on photocurrent response showed the phenylalanine, glycine and glutamine were proportional to the increasing concentration. The photocurrent response with the addition of electrolyte on the analyte showed that the photocurrent response was higher than the Ceq value of each amino acid (196.9825 μA phenylalanine; 130.3333 μA glycine; 194.0193 μA glutamine) whereas without using electrolyte of each amino acid: 84.56667 μAphenylalanine; 60.55863 μA glycine; 91.79087 μA glutamine. This system design is potentially developed for chemical oxygen demand (COD) sensor.
    Keywords: Electrochemical, Amino acid, Photoelectrocatalytic, pH, TiO2, Ti
  • Mohammad Ali Sheikh, Mohseni*, Sajad Pirsa Pages 777-789
    An electrochemical sensor was prepared by the modification of the carbon paste electrode (CPE) with a synthesized nanocomposite. The structure and morphology of the nanocomposite which was prepared by combination of poly pyrrole and copper oxide nanoparticles (PPy/CuO) was studied. This nanocomposite showed good electrocatalytic activity; so that the nanocomposite based electrochemical sensor (CPE-PPy/CuO) exhibited an excellent electroanalysis signals toward oxidation of dopamine (DA) and acetaminophen (AC). This effect is concluded from the high conductivity, low electron transfer resistance and catalytic effect of the PPy/CuO. The fabricated sensor had a lower overvoltage and higher electrical current respect to the bare CPE, for both DA and AC. Also, this sensor can resolve the overlapped anodic peaks of DA and AC and therefore it was used in the simultaneous determination. The calibration plots with wide linear ranges and suitable sensitivity was obtained for DA and AC by differential pulse voltammetry. Also good detection limits were found including 0.020 μM for DA and 0.025 μM for AC. Finally, the electrochemical sensor was used for determination in real samples.
    Keywords: Electrochemical sensor, Nanocomposite, Conducting polymer, Dopamine, Acetaminophen
  • Mohammad Hasanzadeh*, Ayub Karimzadeh, Ahad Mokhtarzadeh, Nasrin Shadjou Pages 790-802
    As a laboratory technique, the analysis of amino acid plays an important role in biochemical, pharmaceutical and biomedical fields. There is, therefore, a need for the rapid and accurate analysis of amino acid. In this report, the Fe3O4 magnetic nanoparticles/graphene quantum dots (Fe3O4 MNP-GQDs) was used for the investigation of electroactive amino acids effect on the electrochemical signals of each other. This sensor used towards probing the interaction study of electroactive amino acids with each other at physiological pH (pH=7.4) by differential pulse voltammetry. The herein described approach is expected to promote the exploitation of electrochemically-based methods for the study of amino acids-amino acid interaction which is necessary in biochemical and biosensing studies. This report may open a new window to direct peptide analysis in the future.
    Keywords: Magnetic nanoparticles, Graphene quantum dot, Electrochemistry, Amino acid