University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
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Email: schalk@unf.edu
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Bioelectrochemistry

  • Publisher: Elsevier
  • FAD Code: BECH
  • CODEN: BIOEFK
  • ISSN: 1567-5394
  • Abbreviation: Bioelectrochemistry
  • DOI Prefix: 10.1016/j.bioelechem,10.1016/S1567-5394
  • Language: English
  • Comments: Fulltext from 1974 V1

Citations 10

"Real-time Assay Of Immobilized Tannase With A Stopped-flow Conductometric Device"
Bioelectrochemistry 2006 Volume 69, Issue 1 Pages 113-116
Fu-Shiang Chang, Po-Chung Chen, Richie L.C. Chen, Fu-Ming Lu and Tzong-Jih Cheng

Abstract: A stopped-flow manifold was developed to assay and characterize immobilized tannase (EC 3.1.1.20). The immobilized enzyme reactor was inserted within the tube-type electrode pair (cell constant = 103.2 cm- 1) for a real-time conductometric measurement. Tris buffer (2 mM, pH = 7.0) was used as the carrier for sensitivity improvement. The activities and kinetic parameters (Km values) for propyl gallate, methyl gallate and tannic acid were investigated.

"Characterization Of Natural Chitosan Membranes From The Carapace Of The Soldier Crab Mictyris Brevidactylus And Its Application To Immobilize Glucose Oxidase In Amperometric Flow-injection Biosensing System"
Bioelectrochemistry 2006 Volume 68, Issue 1 Pages 72-80
Po-Chung Chen, Bo-Chuan Hsieh, Richie L.C. Chen, Tzu-Yu Wang, Hsien-Yi Hsiao and Tzong-Jih Cheng

Abstract: This study investigated characteristics of a chitosan membrane from the carapace of the soldier crab Mictyris brevidactylus intended to construct an amperometric biosensor. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used in this study to characterize these chitosan membranes intended for constructing enzymatic biosensors. Chitosan membranes suffering various durations (> 10 min) of deacetylation had small charge-transfer resistances (< 7.88 k?) but large double-layer capacitances (> 0.55 ?F). They were found in EIS where both the solution resistance and Warburg impedance upon electrode interface were almost independent of the durations and degree of deacetylation. The degree of deacetylation and the thickness of chitosan membranes were also determined. Membrane thickness was slightly dependent with the duration but degree of deacetylation was slightly dependent on the duration. Chitosan membranes with various thicknesses suffered various durations of deacetylation, but this did not influence their electrochemical characteristics. The chitinous membrane was covalently immobilized with glucose oxidase (EC 1.3.4.3) and then attached onto the platinum electrode of a homemade amperometric flow cell. Sensor signal was linearly related to glucose concentration (r = 0.999 for glucose up to 1.0 mM). The system was sensitive (S / N > 5 for 10 ?M glucose) and reproducible (CV < 1.3% for 50 ?M glucose, n = 5). © 2005 Elsevier B.V. All rights reserved.

"A Chemiluminescence Method For The Detection Of Electrochemically Generated H2O2 And Ferryl Porphyrin"
Bioelectrochemistry 2006 Volume 68, Issue 1 Pages 31-39
Sohel RanaCorresponding Author Contact Information, E-mail The Corresponding Author and Keietsu Tamagake

Abstract: Electrochemical formation of H2O2 and the subsequent ferryl porphyrin were examined by measuring luminol chemiluminescence and absorption spectrum using flow-injection method. Emission was observed under the cathodic potential (0.05 V at pH 2.0 and - 0.3V at pH 11.0) by the electrochemical reduction of buffer electrolytes solution but no emission was observed at anodic potentials. Fe(III)TMPyP solution was added at the down stream of the working electrode and was essential for the emission. Removal of dissolved O2 resulted in the decrease of emission intensity by more than 70%. In order to examine the lifetime of reduced active species, delay tubes were used in between working electrode and Fe(III)TMPyP inlet. Experimental results suggested the active species were stable for quite long. The emission was quenched considerably (> 90%) when hydroperoxy catalase was added at the down stream of the working electrode whereas SOD had little effect. Significant inhibition of the emission by the addition of alkene at the down stream of the Fe(III)TMPyP inlet was considered as evidence of oxo-ferryl formation. The spectra at reduction potential under aerated condition were shifted to the longer wavelength (> 430 nm) compared to the original spectrum of Fe(III)TMPyP (422 nm). All the spectra were perfectly reproduced by a combination of Fe(III)TMPyP and OFeIVTMPyP (438 nm) spectra. These observations lead to the conclusion that H 2O2 was produced first by electrochemical reduction of O2, which then converted Fe(III)TMPyP into OFe IVTMPyP to activate luminol. The current efficiencies for the formation of H2O2 were estimated as about 30-65% in all over the pH. © 2005 Elsevier B.V. All rights reserved.

"Electrocatalytic Oxidation Of Ascorbate By Heme-FeIII/heme-FeII Redox Couple Of The HRP And Its Effect On The Electrochemical Behaviour Of An -lactate Biosensor"
Bioelectrochemistry 2004 Volume 64, Issue 1 Pages 71-78
Sophie Ledru and Mohammed Boujtita

Abstract: The measurements of -lactate using the carbon paste electrode modified with lactate oxidase (LOD), horseradish peroxidase (HRP) and ferrocene (FcH) operating at low working potential in flow injection mode showed that the intensity as well as the shape of peaks were dependent on the concentration of the reducing species present in samples (e.g. ascorbate) even at low operating potentials (-200 to 0 mV vs. Ag/AgCl). The mechanism of the electrochemical contribution of ascorbate to the -lactate response was examined by using cyclic voltammetry, hydrodynamic voltammetry and FIA results. Comparative studies showed that HRP was catalytically active for the oxidation of ascorbate leading to a decrease in the cathodic electrochemical signal of -lactate. The results of our investigation postulated that the direct electron transfer from the HRP-Fe(III)/HRP-Fe(II) redox couple to the electrode surface was involved in the electrocatalytic oxidation of ascorbate at the electrode surface.

"An Integrated Bienzyme Glucose Oxidase-fructose Dehydrogenase-tetrathiafulvalene-3-mercaptopropionic Acid-gold Electrode For The Simultaneous Determination Of Glucose And Fructose"
Bioelectrochemistry 2004 Volume 63, Issue 1-2 Pages 199-206
Susana Campuzano, &Oacute;scar A. Loaiza, Mar&iacute;a Pedrero, F. Javier Manuel de Villena and Jos&eacute; M. Pingarr&oacute;n

Abstract: A bienzyme biosensor for the simultaneous determination of glucose and fructose was developed by co-immobilizing glucose oxidase (GOD), fructose dehydrogenase (FDH), and the mediator, tetrathiafulvalene (TTF), by cross-linking with glutaraldehyde atop a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM) on a gold disk electrode (AuE). The performance of this bienzyme electrode under batch and flow injection (FI) conditions, as well as an amperometric detection in high-performance liquid chromatography (HPLC), are reported. The order of enzyme immobilization atop the MPA-SAM affected the biosensor amperometric response in terms of sensitivity, with the immobilization order GOD, FDH, TTF being selected. Similar analytical characteristics to those obtained with single GOD or FDH SAM-based biosensors for glucose and fructose were achieved with the bienzyme electrode, indicating that no noticeable changes in the biosensor responses to the analytes occurred as a consequence of the coimmobilization of both enzymes on the same MPA-AuE. The suitability of the bienzyme biosensor for the analysis of real samples under flow injection conditions was tested by determining glucose in two certified serum samples. The simultaneous determination of glucose and fructose in the same sample cannot be performed without a separation step because at the detection potential used (+0.10 V), both sugars show amperometric response. Consequently, HPLC with amperometric detection at the TTF-FDH-GOD-MPA-AuE was accomplished. Glucose and fructose were simultaneously determined in honey, cola soft drink, and commercial apple juice, and the results were compared with those obtained by using other reference methods.

"Sequential-injection Stripping Analysis Of Nifuroxime Using DNA-modified Glassy Carbon Electrodes"
Bioelectrochemistry 2003 Volume 61, Issue 1-2 Pages 57-63
Nizam Diab, Ali AbuZuhri and Wolfgang Schuhmann

Abstract: The voltammetric behavior of nifuroxime was investigated comparing stationary voltammetric methods with the recently proposed sequential-injection stripping analysis (SISA), by using cyclic voltammetry (CV) and differential-pulse voltammetry at bare and DNA-modified glassy carbon (GC) electrodes. In cyclic voltammetry, reduction of nifuroxime at DNA-modified electrodes gives rise to a well-defined peak, and in contrast to bare GC surfaces, a re-oxidation peak could be observed. Optimization of the pre-concentration process at the DNA-modified surface led to a significant enhancement of the voltammetric current response, a better defined peak shape and an improved dynamic range. Based on this optimized voltammetric procedure, SISA has been evaluated for the determination of nifuroxime. The flow-system significantly facilitates the regeneration of the DNA-modified electrode surface, hence diminishing problems related to accumulation and memory effects. The linear detection range could be extended to 65 µM with a detection limit (3 s) of 0.68 µM, which corresponds to an absolute amount of 21 ng nifuroxime.

"Electrochemical Studies On Reconstituted Horseradish Peroxidase Modified Carbon Paste Electrodes"
Bioelectrochemistry 2002 Volume 56, Issue 1-2 Pages 107-111
Shailly Varma

Abstract: Horseradish peroxidase (HRP) is a heme protein that acts specifically on H2O2 as the electron acceptor. Hemin (Ferriprotoporhyrin-IX) is the prosthetic group of the enzyme. A direct molecular wire to the redox center of the enzyme is expected to enhance the electrochemical response of the enzyme. Native HRP was immobilized onto the surface of glassy carbon (GC) matrix using a 16-atom spacer arm. We have also immobilized the redox center of the enzyme (hemin) through one of the propionate groups onto the surface of glassy carbon matrix using an 11-atom spacer arm with amino terminus. Apoperoxidase was isolated according to the Teales method and was allowed to reconstitute with the hemin-bound matrix for enzyme reconstitution. The HRP paste and reconstituted-HRP (rec-HRP) paste electrodes were used to study the electrochemical response to substrate H,02 using electrochemical techniques like cyclic voltammetry (CV) and flow injection (FI) studies. Flow injection studies using HRP paste electrode showed a linearity from 25 to 200 muM H2O2. The rec-HRP paste showed similar to100 times increase in the electron transfer rates compared to native HRP paste, and substrate linearity from 25 to 100 muM was observed. (C) 2002 Elsevier Science B.V. All rights reserved.

"Electrosynthesis Of Poly-o-diaminobenzene On The Prussian Blue Modified Electrodes For Improvement Of Hydrogen Peroxide Transducer Characteristics"
Bioelectrochemistry 2002 Volume 55, Issue 1-2 Pages 145-148
Lilia V. Lukachova, Elena A. Kotel'nikova, Daniele D'Ottavi, Egor A. Shkerin, Elena E. Karyakina, Danila Moscone, Giuseppe Palleschi, Antonella Curulli and Arkady A. Karyakin

Abstract: Electropolymerisation of nonconducting polymer, poly-(1,2-diaminobenzene) on the top of Prussian Blue (PB) modified electrode led to significant improvement of resulting hydrogen peroxide transducer selectivity and operational stability. The reported transducer retained 100% of response during 20 h under the continuous flow of 0.1 mM H(2)O(2), and thus improves the stability level in selective peroxide detection by one order of magnitude. The selectivity value of the PB-poly(1,2-DAB) based H(2)O(2) sensor in relation to ascorbate is approximately 600. No signals to acetaminophen and urate were investigated. PB-poly(1,2-diaminobenzene) modified electrode allows the detection of H(2)O(2) in the flow injection mode down to 10^-7 M with the sensitivity 0.3 A M-1 cm-2, which is only two times lower compared to the uncovered PB based transducer. [Journal Article; In English; Netherlands]

"Effect Of PH On Direct Electron Transfer In The System Gold Electrode-recombinant Horseradish Peroxidase"
Bioelectrochemistry 2002 Volume 55, Issue 1-2 Pages 83-87
Elena Ferapontova and Lo Gorton

Abstract: The effect of pH on the kinetics of the bioelectrocatalytic reduction of H2O2 catalyzed by horseradish peroxidase (HRP) has been studied at -50 mV vs. Ag/AgCl on HRP-modified Au electrodes placed in a wall-jet flow-through electrochemical cell. Native HRP (nHRP) and a nonglycosylated recombinant form containing a six-histidine tag at the C-terminus, CHisrHRP, produced by genetic engineering of nonglycosylated recombinant HRP using an E. coli expression system, have been used for adsorptive modification of Au electrodes. A favourable adsorption of CHisrHRP on preoxidized Au from a protein solution at pH 6.0 provided a high and stable current response to H2O2 due to its bioelectrocatalytic reduction based on direct (mediatorless) electron transfer (ET) between Au and the active site of HRP. The heterogeneous ET rate constant, ks, calculated from experimental data on direct ET, on mediated ET in the presence of catechol as well as from microbalance data, increased more than 30 times when changing from nHRP to CHisrHRP. For both forms of HRP, the increasing efficiency of bioelectrocatalysis with increasing [H3O+] was observed. The values of the apparent ks between CHisrHRP and Au changed from a value of 12±2 s-1 in PBS at pH 8.0 to a value of 434±62 s-1 at pH 6.0; a similar ks-pH dependence was also observed for nHRP, providing the possibility to consider the reaction mechanism involving the participation of a proton in the rate-determining step of the charge transfer.

"An Electrochemical Multienzymatic Biosensor For Determination Of Cholesterol"
Bioelectrochemistry 2001 Volume 54, Issue 1 Pages 17-22
Cristiana Bongiovanni, Tommaso Ferri, Alessandro Poscia, Maurizio Varalli, Roberto Santucci and Alessandro Desideri

Abstract: This paper describes an electrochemical biosensor for free cholesterol monitoring. The sensor is a multienzymatic electrodic system in which horseradish peroxidase and cholesterol oxidase are simultaneously immobilized within a polymeric film, on the surface of a pyrolitic graphite electrode. From voltammetric and amperometric (flow injection) data obtained, the efficiency, reproducibility and stability of the system are discussed. Results obtained, of interest for basic and applied biochemistry, represent a first step for construction of a mediator-free biosensor with potentialities for a successful application in the biosensor area.