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Tse-chuan Chou - One of the best experts on this subject based on the ideXlab platform.

  • a nonenzymatic Amperometric Method for fructosyl valine sensing using ferroceneboronic acid
    Electroanalysis, 2011
    Co-Authors: Hui-ching Chien, Tse-chuan Chou
    Abstract:

    Fructosyl valine (Fru-Val) is a glycosylated component of hemoglobin (HbA1c) that can serve as a diagnostic target for type 2 diabetes. While average blood glucose levels fluctuate significantly, the more stable levels of HbA1c can serve as a better long-term diagnostic marker. Here a diagnostic system, incorporating an Amperometric Method, for detecting Fru-Val (at +0.1 V vs. Ag/AgCl), using ferrocene boronic acid (FcBA) is presented. FcBA can complex diols, and has easily detectable redox properties. The boronic acid group in FcBA mediates complexation, while the Fe(II)/Fe(III) couple serves as a transducer. The diagnostic system, based on a miniaturized bare glassy carbon paste electrode (GCPE), has a fast response time.

  • A Nonenzymatic Amperometric Method for Fructosyl‐Valine Sensing Using Ferroceneboronic Acid
    Electroanalysis, 2010
    Co-Authors: Hui-ching Chien, Tse-chuan Chou
    Abstract:

    Fructosyl valine (Fru-Val) is a glycosylated component of hemoglobin (HbA1c) that can serve as a diagnostic target for type 2 diabetes. While average blood glucose levels fluctuate significantly, the more stable levels of HbA1c can serve as a better long-term diagnostic marker. Here a diagnostic system, incorporating an Amperometric Method, for detecting Fru-Val (at +0.1 V vs. Ag/AgCl), using ferrocene boronic acid (FcBA) is presented. FcBA can complex diols, and has easily detectable redox properties. The boronic acid group in FcBA mediates complexation, while the Fe(II)/Fe(III) couple serves as a transducer. The diagnostic system, based on a miniaturized bare glassy carbon paste electrode (GCPE), has a fast response time.

Tautgirdas Ruzgas - One of the best experts on this subject based on the ideXlab platform.

  • Amperometric monitoring of redox activity in living yeast cells: comparison of menadione and menadione sodium bisulfite as electron transfer mediators
    Electrochemistry Communications, 2004
    Co-Authors: Arto Heiskanen, Ch. Spégel, Julia Yakovleva, Rafael J. Taboryski, Milena Koudelka-hep, Jenny Emnéus, Tautgirdas Ruzgas
    Abstract:

    An Amperometric Method was applied for real-time monitoring of intracellular redox enzyme activity. Baker’s yeast (Saccharomyces cerevisiae) cells were immobilized on platinum microband electrodes and mediated anodic currents were measured. The currents were observed in the absence and in the presence of glucose as a source of reducing equivalents, NADH and NADPH. 2-Methyl-1,4-naphthoquinone (menadione, vitamin K3) and water soluble 2-methyl-1,4-naphthoquinone sodium bisulfite (menadione sodium bisulfite MSB) were compared as artificial electron acceptors for their ability to transduce internal cellular redox activity into electrode current. It was found that hydrophobic menadione was superior to its water-soluble bisulfite derivative for probing whole intact cells.

  • Amperometric monitoring of redox activity in living yeast cells: comparison of menadione and menadione sodium bisulfite as electron transfer mediators
    Elsevier, 2004
    Co-Authors: Arto Heiskanen, Ch. Spégel, Julia Yakovleva, Rafael J. Taboryski, Milena Koudelka-hep, Jenny Emnéus, Tautgirdas Ruzgas
    Abstract:

    An Amperometric Method was applied for real-time monitoring of intracellular redox enzyme activity. Baker’s yeast (Saccharomyces cerevisiae) cells were immobilized on platinum microband electrodes and mediated anodic currents were measured. The currents were observed in the absence and in the presence of glucose as a source of reducing equivalents, NADH and NADPH. 2-Methyl-1,4-naphthoquinone (menadione, vitamin K3) and water soluble 2-methyl-1,4-naphthoquinone sodium bisulfite (menadione sodium bisulfite MSB) were compared as artificial electron acceptors for their ability to transduce internal cellular redox activity into electrode current. It was found that hydrophobic menadione was superior to its water-soluble bisulfite derivative for probing whole intact cells. Keywords: Amperometric Method, Living cells, NAD(P)H oxidizing enzymes, Artificial electron acceptors, Real-tim

Patricia I. Ortiz - One of the best experts on this subject based on the ideXlab platform.

  • Determination of Azithromycin by an alternative FIA Amperometric Method for different pharmaceutical applications
    Industrial & Engineering Chemistry Research, 2013
    Co-Authors: Valeria Pfaffen, Sonia N. Faudone, Norma R. Sperandeo, Silvia Lucia Cuffini, Patricia I. Ortiz
    Abstract:

    This work presents a fast and reliable electroanalytical procedure for the quantification of azithromycin (AZ) in different systems that couples flow injection analysis and Amperometric detection (FIA-AM). The quantification was performed at a working potential of 1.20 V (vs Ag/AgCl/NaCl (3 M)) in 0.05 M phosphate buffer at a flow rate of 1.0 mL min −1 . Under these conditions a 1.00 × 10 −6 −1.50 × 10 −5 M linear range, (5.8 ± 0.4) × 10 4 CAZ (μ AM −1 ) sensitivity and 4.44 × 10 −7 M limit of detection are obtained. Also, this technique can be used without sample pretreatment and presents good reproducibility. The procedure was applied to the determination of the content of AZ in commercial tablets, to study the intrinsic dissolution rate of compacts of AZ dihydrate, and to determine the AZ release from a AZ hydrogel and carbomer. The Method was statistically analyzed and proves to be reliable and robust. However, more remarkable is that FIA-AM technique presents better sensitivity and high sampling rate.

  • Alternative Method with Amperometric Detection for Ranitidine Determination
    Industrial & Engineering Chemistry Research, 2010
    Co-Authors: Valeria Pfaffen, Patricia I. Ortiz
    Abstract:

    An alternative, simple, and reliable FIA Amperometric Method for ranitidine quantification was developed. A working glassy carbon electrode and a Ag|AgCl|NaCl (3 M) reference electrode were used. T...

  • new automatized Method with Amperometric detection for the determination of azithromycin
    Talanta, 2007
    Co-Authors: Miriam E Palomeque, Patricia I. Ortiz
    Abstract:

    Abstract A FIA–Amperometric Method for azithromycin determination was developed. A working glassy carbon electrode and a Ag/AgCl/NaCl (3 M) reference electrode were used. The determination is based on the electrochemical oxidation of the azithromycin at 0.9 V in Britton–Robinson buffer solution (pH 8.0). Due to the adsorption of the reaction products on the electrode surface, an effective cleaner cycle was implemented. By using the optimum chemical and FIA conditions, a concentration linear range of 1.0–10.0 mg L −1 and a detection limit (LOD) of 0.76 mg L −1 are obtained. The Method was validated and satisfactorily applied to the determination of azithromycin in pharmaceutical formulations.

Arto Heiskanen - One of the best experts on this subject based on the ideXlab platform.

  • Amperometric monitoring of redox activity in living yeast cells: comparison of menadione and menadione sodium bisulfite as electron transfer mediators
    Electrochemistry Communications, 2004
    Co-Authors: Arto Heiskanen, Ch. Spégel, Julia Yakovleva, Rafael J. Taboryski, Milena Koudelka-hep, Jenny Emnéus, Tautgirdas Ruzgas
    Abstract:

    An Amperometric Method was applied for real-time monitoring of intracellular redox enzyme activity. Baker’s yeast (Saccharomyces cerevisiae) cells were immobilized on platinum microband electrodes and mediated anodic currents were measured. The currents were observed in the absence and in the presence of glucose as a source of reducing equivalents, NADH and NADPH. 2-Methyl-1,4-naphthoquinone (menadione, vitamin K3) and water soluble 2-methyl-1,4-naphthoquinone sodium bisulfite (menadione sodium bisulfite MSB) were compared as artificial electron acceptors for their ability to transduce internal cellular redox activity into electrode current. It was found that hydrophobic menadione was superior to its water-soluble bisulfite derivative for probing whole intact cells.

  • Amperometric monitoring of redox activity in living yeast cells: comparison of menadione and menadione sodium bisulfite as electron transfer mediators
    Elsevier, 2004
    Co-Authors: Arto Heiskanen, Ch. Spégel, Julia Yakovleva, Rafael J. Taboryski, Milena Koudelka-hep, Jenny Emnéus, Tautgirdas Ruzgas
    Abstract:

    An Amperometric Method was applied for real-time monitoring of intracellular redox enzyme activity. Baker’s yeast (Saccharomyces cerevisiae) cells were immobilized on platinum microband electrodes and mediated anodic currents were measured. The currents were observed in the absence and in the presence of glucose as a source of reducing equivalents, NADH and NADPH. 2-Methyl-1,4-naphthoquinone (menadione, vitamin K3) and water soluble 2-methyl-1,4-naphthoquinone sodium bisulfite (menadione sodium bisulfite MSB) were compared as artificial electron acceptors for their ability to transduce internal cellular redox activity into electrode current. It was found that hydrophobic menadione was superior to its water-soluble bisulfite derivative for probing whole intact cells. Keywords: Amperometric Method, Living cells, NAD(P)H oxidizing enzymes, Artificial electron acceptors, Real-tim

Ch. Spégel - One of the best experts on this subject based on the ideXlab platform.

  • Amperometric monitoring of redox activity in living yeast cells:comparison of menadione sodium bisulfite as electron transfer mediators
    'Elsevier BV', 2009
    Co-Authors: Heiskanen A., Jakovleva J., Ch. Spégel, Koudelka-hep M., Emnéus J., Ruzgas T., Taboryski R.
    Abstract:

    An Amperometric Method was applied for real-time monitoring of intracellular redox enzyme activity. Baker's yeast (Saccharomyces cerevisiae) cells were immobilized on platinum microband electrodes and mediated anodic currents were measured. The currents were observed in the absence and in the presence of glucose as a source of reducing equivalents, NADH and NADPH. 2-Methyl-1,4-naphthoquinone (menadione, vitamin K3) and water soluble 2-methyl-1,4-naphthoquinone sodium bisulfite (menadione sodium bisulfite MSB) were compared as artificial electron acceptors for their ability to transduce internal cellular redox activity into electrode current. It was found that hydrophobic menadione was superior to its water-soluble bisulfite derivative for probing whole intact cells. © 2003 Elsevier B.V. All rights reserved

  • Amperometric monitoring of redox activity in living yeast cells: comparison of menadione and menadione sodium bisulfite as electron transfer mediators
    Electrochemistry Communications, 2004
    Co-Authors: Arto Heiskanen, Ch. Spégel, Julia Yakovleva, Rafael J. Taboryski, Milena Koudelka-hep, Jenny Emnéus, Tautgirdas Ruzgas
    Abstract:

    An Amperometric Method was applied for real-time monitoring of intracellular redox enzyme activity. Baker’s yeast (Saccharomyces cerevisiae) cells were immobilized on platinum microband electrodes and mediated anodic currents were measured. The currents were observed in the absence and in the presence of glucose as a source of reducing equivalents, NADH and NADPH. 2-Methyl-1,4-naphthoquinone (menadione, vitamin K3) and water soluble 2-methyl-1,4-naphthoquinone sodium bisulfite (menadione sodium bisulfite MSB) were compared as artificial electron acceptors for their ability to transduce internal cellular redox activity into electrode current. It was found that hydrophobic menadione was superior to its water-soluble bisulfite derivative for probing whole intact cells.

  • Amperometric monitoring of redox activity in living yeast cells: comparison of menadione and menadione sodium bisulfite as electron transfer mediators
    Elsevier, 2004
    Co-Authors: Arto Heiskanen, Ch. Spégel, Julia Yakovleva, Rafael J. Taboryski, Milena Koudelka-hep, Jenny Emnéus, Tautgirdas Ruzgas
    Abstract:

    An Amperometric Method was applied for real-time monitoring of intracellular redox enzyme activity. Baker’s yeast (Saccharomyces cerevisiae) cells were immobilized on platinum microband electrodes and mediated anodic currents were measured. The currents were observed in the absence and in the presence of glucose as a source of reducing equivalents, NADH and NADPH. 2-Methyl-1,4-naphthoquinone (menadione, vitamin K3) and water soluble 2-methyl-1,4-naphthoquinone sodium bisulfite (menadione sodium bisulfite MSB) were compared as artificial electron acceptors for their ability to transduce internal cellular redox activity into electrode current. It was found that hydrophobic menadione was superior to its water-soluble bisulfite derivative for probing whole intact cells. Keywords: Amperometric Method, Living cells, NAD(P)H oxidizing enzymes, Artificial electron acceptors, Real-tim