University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Soichi Yabuki

Abbrev:
Yabuki, S.
Other Names:
Address:
National Institute of Bioscience and Human-Technology, 1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
Phone:
NA
Fax:
+81-298-61-6166

Citations 4

"Preparation Of D-amino Acid Oxidase-immobilized Polyion Complex Membranes"
Sens. Actuat. B 2001 Volume 76, Issue 1-3 Pages 142-146
Soichi Yabuki, Fumio Mizutani and Yoshiki Hirata

Abstract: D-Amino acid oxidase (DAAO) catalyzes the D-amino acids which size around 100 Da. Polyion complex (PIC) membrane shows the permeability changes with the solute size of 110 Da. Combining the DAAO and PIC membrane, sensitivity of the enzyme electrode that depends on the molecular mass of substrates could be adjusted; three PIC-DAAO electrodes, a glassy carbon (GC)/PIC/DAAO electrode (El), a GC/DAAO-entrapped PIC (E2) and a GC/DAAO-entrapped PIC/PIC (E3) were prepared on the GC base electrodes. The current responses to D-amino acids were measured by the oxidation of hydrogen peroxide, which was produced through the DAAO catalysis. Relative response on E2 to El to D-amino acids with its molecular weight over the 110 Da (D-phenylalanine (PHE), D-methionine (MET), D-valine (VAL)) was low compared with that to small D-amino acids (D-alanine (ALA) and D-serine (SER)), because of the suppression of penetration in PIG. The effect of penetration suppression was appeared remarkably in the E3: owing to the completely coverage of PIC on enzyme layer. On the E2, the sensitivity of the five D-amino acids, D-ALA, D-SER, D-VAL, D-MET and D-PHE, were almost same (175±25 nA at 0.5 mM). The E2 would be used as a biosensor for measuring total amount of these five D-amino acids. (C) 2001 Elsevier Science B.V. All rights reserved.

"Preparation Of A Microperoxidase And Ferrocene-immobilized Polyion Complex Membrane For The Detection Of Hydrogen Peroxide"
J. Electroanal. Chem. 1999 Volume 468, Issue 1 Pages 117-120
Soichi Yabuki, Fumio Mizutani and Yoshiki Hirata

Abstract: A polyion complex membrane containing physically entrapped microperoxidase and ferrocene was prepared on a glassy carbon electrode. A reductive current response for H2O2 was obtained under the application of 0.0 V versus Ag AgCl. The current response was proportional to the H2O2 concentration up to 20 µM, and the lower detection limit was 0.5 µM (S/N = 5). The interference current from L-ascorbate was ~45% of the current for the same concentration of H2O2. The electrode could be used for 10 days. The electrode was applied as the transducer of an oxidase-based sensor such as a glucose oxidase-based one: the glucose-sensing electrode prepared showed high sensitivity (lower detection limit, 5 µM).

"Preparation Of A Glucose-sensing Electrode Based On Glucose Oxidase-attached Polyion Complex Membrane Containing Microperoxidase And Ferrocene"
Electrochemistry 2000 Volume 68, Issue 11 Pages 853-855
Soichi YABUKI, Fumio MIZUTANI, Yoshiki HIRATA

Abstract: A glucose oxidase-attached polyion complex membrane containing microperoxidase and ferrocene was formed on a carbon electrode. The enzyme electrode gave a reductive current response (100% response time, within 20 s), and steady-state response was proportional to the glucose concentration up to 0.2 mM. Lower detection limit was 1 µ-M The current response decreased gradually, owing to the loss of the microperoxidase activity. The enzyme electrode was used for the detection of glucose concentration in beverages. The results obtained agreed well with those obtained by Boehringer F-kit method. The electrode would be useful as a glucose biosensor for real samples.
Glucose Polymer

"Glucose-sensing Electrode Based On Glucose Oxidase-attached Polyion Complex Membrane Containing Peroxidase And Ferrocene"
Electroanalysis 2001 Volume 13, Issue 5 Pages 380-383
Soichi Yabuki, Fumio Mizutani, Yoshiki Hirata

Abstract: A glucose oxidase (GOD)-attached polyion complex membrane containing peroxidase (POD) and ferrocene was prepared by two steps on a glassy carbon electrode. First, a polyion complex membrane containing POD and ferrocene was prepared: a poly-L-lysine solution, a POD solution, a ferrocene dispersion and a poly(styrenesulfonate) solution were successively dropped on an electrode, and the electrode was allowed to dry. Then GOD was attached by the use of glutaraldehyde: GOD and glutaraldehyde solutions were dropped on the membrane. and the electrode was dried. Current response to glucose for the enzyme electrode was measured at a potential of -0.2 V (vs. Ag/AgCl). The 100 % response time was ~20 s. The current was proportional to the glucose concentration up to 0.1 mM. The lower detection limit was 1 muM (signal-to-noise ratio. S/N = 5). The enzyme electrode was used for the glucose measurements in beverages. The results obtained agreed well with those obtained by Boehringer F-kit method. The electrode would be useful as a glucose biosensor for beverages.
Polymer