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Tanaka K, Shoji A, Sugawara M. An enzyme-entrapped agarose gel for visualization of ischemia-induced L-glutamate fluxes in hippocampal slices in a flow system. ANAL SCI 2015; 31:321-5. [PMID: 25864676 DOI: 10.2116/analsci.31.321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An agarose gel slip containing L-glutamate oxidase (GluOx), horseradish peroxidase (HRP) and a dye DA-64 is proposed as a tool for visualizing ischemia-induced L-glutamate release in hippocampal slices in a flow system. The agarose slip with a detection limit of 6.0 ± 0.8 μmol L(-1) for L-glutamate enabled us to visualize L-glutamate fluxes in a flow system. The leak of a dye from the agarose gel was negligible and a diffusion blur due to spreading of Bindshedler's Green (BG) within the gel was suppressed. Monitoring the time-dependent change of ischemia-induced L-glutamate fluxes at neuronal regions CA1, DG and CA3 of hippocampal slices is demonstrated.
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Affiliation(s)
- Kazuhisa Tanaka
- Department of Chemistry, College of Humanities and Sciences, Nihon University
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2
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Inoue KY, Matsudaira M, Nakano M, Ino K, Sakamoto C, Kanno Y, Kubo R, Kunikata R, Kira A, Suda A, Tsurumi R, Shioya T, Yoshida S, Muroyama M, Ishikawa T, Shiku H, Satoh S, Esashi M, Matsue T. Advanced LSI-based amperometric sensor array with light-shielding structure for effective removal of photocurrent and mode selectable function for individual operation of 400 electrodes. LAB ON A CHIP 2015; 15:848-856. [PMID: 25483361 DOI: 10.1039/c4lc01099j] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have developed a large-scale integrated (LSI) complementary metal-oxide semiconductor (CMOS)-based amperometric sensor array system called "Bio-LSI" as a platform for electrochemical bio-imaging and multi-point biosensing with 400 measurement points. In this study, we newly developed a Bio-LSI chip with a light-shield structure and a mode-selectable function with the aim of extending the application range of Bio-LSI. The light shield created by the top metal layer of the LSI chip significantly reduces the noise generated by the photocurrent, whose value is less than 1% of the previous Bio-LSI without the light shield. The mode-selectable function enables the individual operation of 400 electrodes in off, electrometer, V1, and V2 mode. The off-mode cuts the electrode from the electric circuit. The electrometer-mode reads out the electrode potential. The V1-mode and the V2-mode set the selected sensor electrode at two different independent voltages and read out the current. We demonstrated the usefulness of the mode-selectable function. First, we displayed a dot picture based on the redox reactions of 2.0 mM ferrocenemethanol at 400 electrodes by applying two different independent voltages using the V1 and V2 modes. Second, we carried out a simultaneous detection of O2 and H2O2 using the V1 and V2 modes. Third, we used the off and V1 modes for the modification of the osmium-polyvinylpyridine gel polymer containing horseradish peroxidase (Os-HRP) at the selected electrodes, which act as sensors for H2O2. These results confirm that the advanced version of Bio-LSI is a promising tool that can be applied to a wide range of analytical fields.
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Affiliation(s)
- Kumi Y Inoue
- Graduate School of Environmental Studies, Tohoku University, 6-6-11 Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-8579, Japan.
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3
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Ikegami Y, Hozumi S, Shoji A, Hirano-Iwata A, Bliss T, Sugawara M. Real-time monitoring of extracellular l-glutamate levels released by high-frequency stimulation at region CA1 of hippocampal slices with a glass capillary-based l-glutamate sensor. SENSING AND BIO-SENSING RESEARCH 2014. [DOI: 10.1016/j.sbsr.2014.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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4
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Hozumi S, Ikezawa K, Shoji A, Hirano-Iwata A, Bliss T, Sugawara M. Simultaneous monitoring of excitatory postsynaptic potentials and extracellular L-glutamate in mouse hippocampal slices. Biosens Bioelectron 2010; 26:2975-80. [PMID: 21194919 DOI: 10.1016/j.bios.2010.11.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 11/22/2010] [Accepted: 11/29/2010] [Indexed: 11/30/2022]
Abstract
Simultaneous monitoring of amperometric currents at a glass capillary sensor based on recombinant GluOx and field excitatory postsynaptic potentials (fEPSPs) were performed in region CA1 of mouse hippocampal slices. A transient increase in the glutamate current relative to the basal one at control stimulation (0.052Hz) was evoked by stimulation at 2 Hz for 2 min. The magnitude of the glutamate current was dependent on the intensity (current) of a 2 Hz stimulus and reflected the slope of the fEPSP. The in situ calibration of the L-glutamate sensor revealed that the extracellular concentration of L-glutamate released by 2 Hz stimulation before tetanus is in the range from 0.8 to 2.2 μM and it is enhanced after tetanic stimulation. The L-glutamate level at a test stimulus (0.052 Hz) was estimated to be 32 nM. The recombinant GluOx-based sensor exhibited weak responses to glutamine above 300 μM and L-aspartic acid above 200 μM. The potential use of a glass capillary sensor in combination with fEPSP measurements for electrophysiological study is discussed.
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Affiliation(s)
- Shizuko Hozumi
- Department of Chemistry, College of Humanities and Sciences, Nihon University, Sakurajuosui, Setagayaku, Tokyo 156-8550, Japan
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5
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CHIBA H, DEGUCHI Y, KANAZAWA E, KAWAI J, NOZAWA K, SHOJI A, SUGAWARA M. In Vitro Measurements of Extracellular L-Glutamate Level in Region CA3 of Mouse Hippocampal Slices under Chemical Stimulation. ANAL SCI 2010; 26:1103-6. [DOI: 10.2116/analsci.26.1103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Hiromi CHIBA
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Yukari DEGUCHI
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Ena KANAZAWA
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Jun KAWAI
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Keiichiro NOZAWA
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Atsushi SHOJI
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Masao SUGAWARA
- Department of Chemistry, College of Humanities and Sciences, Nihon University
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6
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Inoue KY, Ino K, Shiku H, Kasai S, Yasukawa T, Mizutani F, Matsue T. Electrochemical monitoring of hydrogen peroxide released from leucocytes on horseradish peroxidase redox polymer coated electrode chip. Biosens Bioelectron 2009; 25:1723-8. [PMID: 20060284 DOI: 10.1016/j.bios.2009.12.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 11/27/2009] [Accepted: 12/14/2009] [Indexed: 10/20/2022]
Abstract
We developed an electrochemical-sensing device for continuous monitoring extracellular hydrogen peroxide (H(2)O(2)). The device consists of an indium-tin-oxide electrode coated with osmium-polyvinylpyridine gel polymer containing horseradish peroxidase (Os-HRP) and a poly-dimethyl siloxane well to house the cells on the chip. Granulocyte-like differentiated HL-60 cells were accommodated in the well and stimulated with phorbol 12-myristate 13-acetate (PMA), which triggered the generation of H(2)O(2). The extracellular H(2)O(2) released from the cells was enzymatically reduced at the Os-HRP-modified electrode chip using Os(II) as an electron donor, resulting in reduction current responses by the device. The reduction current increased immediately upon PMA stimulation and this current transient was similar to that obtained by conventional chemiluminescence assays using sodium luminol. Apocynin, an inhibitor of NADPH oxidase activation, eliminated both the electrochemical and chemiluminescence signals. On the other hand, superoxide dismutase (SOD) increased the amperometric signals and catalase (CAT) decreased, whereas SOD decreased luminescence emission and CAT did not. These results were in accordance with the expected reaction mechanism, and strongly indicate that this new electrochemical-sensing device successfully detects extracellular H(2)O(2) production.
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Affiliation(s)
- Kumi Y Inoue
- Graduate School of Environmental Studies, Tohoku University, 6-6-11 Aoba, Aramaki, Aoba, Sendai 980-8579, Japan.
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OKA T, TOMINAGA Y, WAKABAYASHI Y, SHOJI A, SUGAWARA M. Comparison of the L-Glutamate Level in Mouse Hippocampal Slices under Tetraethylammonium Chloride Stimulation as Measured with a Glass Capillary Sensor and a Patch Sensor. ANAL SCI 2009; 25:353-8. [DOI: 10.2116/analsci.25.353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Takayuki OKA
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Yumiko TOMINAGA
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | | | - Atsushi SHOJI
- Department of Chemistry, College of Humanities and Sciences, Nihon University
| | - Masao SUGAWARA
- Department of Chemistry, College of Humanities and Sciences, Nihon University
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Oka T, Tasaki C, Sezaki H, Sugawara M. Implantation of a glass capillary-based enzyme electrode in mouse hippocampal slices for monitoring of L-glutamate release. Anal Bioanal Chem 2007; 388:1673-9. [PMID: 17632704 DOI: 10.1007/s00216-007-1428-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 06/08/2007] [Accepted: 06/08/2007] [Indexed: 11/24/2022]
Abstract
A glass capillary-based enzyme electrode (tip size approximately 10 microm) was implanted in the target neuronal region, i.e., dentate gyrus (DG) or cornu ammonis 1 (CA1), of acute brain slices at a depth of approximately 10 microm from the slice surface in order to allow the monitoring of chemical stimulant-induced changes in L-glutamate levels. First, the sampling behavior of a glass capillary in a slice was investigated by visualizing the transport of a fluorescence dye. Then, the electrode was applied to real-time monitoring of L-glutamate release in acute hippocampal slices stimulated by surface application of a stimulant solution. The extracellular application of KCl (0.10 M) increased the glutamate levels in the DG and CA1 regions, respectively. The enhancement of L-glutamate concentration at DG was much larger than at CA1. The application of tetraethylammonium chloride (TEA) (25 mM) enhanced the L-glutamate level in the DG region and the enhanced level did not return to the initial value before TEA application even when washed with an artificial cerebrospinal fluid (ACSF). The usefulness of a surface-implanted capillary electrode for monitoring L-glutamate release in acute brain slices is discussed.
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Affiliation(s)
- Takayuki Oka
- Department of Chemistry, College of Humanities and Sciences, Nihon University, Sakurajousui, Setagaya, Tokyo, 156-8550, Japan
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Oldenziel WH, van der Zeyden M, Dijkstra G, Ghijsen WEJM, Karst H, Cremers TIFH, Westerink BHC. Monitoring extracellular glutamate in hippocampal slices with a microsensor. J Neurosci Methods 2007; 160:37-44. [PMID: 16978703 DOI: 10.1016/j.jneumeth.2006.08.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 08/08/2006] [Accepted: 08/14/2006] [Indexed: 11/27/2022]
Abstract
The direct local assessment of glutamate in brain slices may improve our understanding of glutamatergic neurotransmission significantly. However, an analytical technique that monitors glutamate directly in brain slices is currently not available. Most recording techniques either monitor derivatives of glutamate or detect glutamate that diffuses out of the slice. Microsensors provide a promising solution to fulfill this analytical requirement. In the present study we have implanted a 10 microm diameter hydrogel-coated microsensor in the CA1 area of hippocampal slices to monitor extracellular glutamate levels. The influence of several pharmacological agents, which facilitate glutamate release from neurons or astrocytes, was investigated to explore the applicability of the microsensor. It was observed that KCl, veratradine, alpha-latrotoxine (LTX), DL-threo-beta-benzyloxyaspartate (dl-TBOA) and L-cystine rapidly increased the extracellular glutamate levels. As far as we know this is the first study in which a microsensor is applied to monitor dynamic changes of glutamate in brain slices and in our opinion this type of research may contribute greatly to improve our understanding of the physiology of glutamatergic neurotransmission.
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Affiliation(s)
- W H Oldenziel
- Department of Biomonitoring and Sensoring, University Center for Pharmacy, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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Sugawara M. Methodological aspects ofin vitro sensing ofL-glutamate in acute brain slices. CHEM REC 2007; 7:317-25. [DOI: 10.1002/tcr.20126] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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11
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Schuvailo O, Gáspár S, Soldatkin A, Csöregi E. Ultramicrobiosensor for the Selective Detection of Glutamate. ELECTROANAL 2007. [DOI: 10.1002/elan.200603707] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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12
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Pauliukaite R, Zhylyak G, Citterio D, Spichiger-Keller UE. l-Glutamate biosensor for estimation of the taste of tomato specimens. Anal Bioanal Chem 2006; 386:220-7. [PMID: 16917673 DOI: 10.1007/s00216-006-0656-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 06/23/2006] [Accepted: 06/27/2006] [Indexed: 10/24/2022]
Abstract
An amperometric biosensor has been developed for measurement of Umami, or the taste based on the amount of L-glutamate, in tomato foods. The biosensor is based on an enzyme-mediator system in which L-glutamate oxidase is used for biochemical oxidation of L-glutamate and a tetrafulvalene-tetracyanoquinodimethane (TTF-TCNQ) paste, prepared from the mixture of TTF-TCNQ salt, graphite powder, and silicone oil, serves as the mediator. The limit of detection, calculated by use of a four-parameter logistic model, was 0.05 mmol L(-1), and the limit of quantification was 0.15 mmol L(-1). The correlation coefficient (R2) was 0.990 and the relative standard deviation was no more than 1% (n=5). The response time (tau (95)) was 20-50 s, depending on concentration. The repeatability of the sensor was better than 5% (n=10). The sensor developed was stable for more than ten days.
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Affiliation(s)
- Rasa Pauliukaite
- Centre for Chemical Sensors and Chemical Information Technology, ETH Technopark, 8005 Zurich, Switzerland
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Shimane M, Miyagawa K, Sugawara M. Detection of γ-aminobutyric acid-induced glutamate release in acute mouse hippocampal slices with a patch sensor. Anal Biochem 2006; 353:83-92. [PMID: 16620752 DOI: 10.1016/j.ab.2006.03.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2005] [Revised: 03/13/2006] [Accepted: 03/16/2006] [Indexed: 12/01/2022]
Abstract
gamma-Aminobutyric acid (GABA)-stimulated release of L-glutamate from various neuronal regions of acute mouse hippocampal slices was detected with a patch sensor that responds to L-glutamate at the sub-micromolar level. The response of the patch sensor to L-glutamate was evaluated in terms of an integrated current. The integrated current increased with the concentration of L-glutamate ranging from 0.50 to 5.0 microM. By using the patch sensor, GABA-induced L-glutamate release from acute mouse hippocampal slices was detected. The effect of antagonists for GABA(A) and GABA(B) receptors on the L-glutamate release was also investigated. The GABA (25 microM) stimulation induced the release of L-glutamate via GABA(A) receptor in the CA1 region, but GABA did not induce L-glutamate release in the CA3 region. However, in the presence of the GABA(B) receptor antagonist (3-aminopropyl)(diethoxymethyl)phosphinic acid (CGP-35348), release of L-glutamate in the CA3 region was evoked by GABA stimulation. The glutamate release was completely suppressed when both GABA(A) and GABA(B) receptor were inhibited. The current results show that the glutamate release in the CA3 region occurs via a GABA(A) pathway when GABA(B) receptors are inhibited.
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Affiliation(s)
- Mitsuyoshi Shimane
- Department of Chemistry, College of Humanities and Sciences, Nihon University, Sakurajousui, Setagaya, Tokyo, Japan
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McMahon CP, Rocchitta G, Serra PA, Kirwan SM, Lowry JP, O'Neill RD. The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity. Analyst 2006; 131:68-72. [PMID: 16365665 DOI: 10.1039/b511643k] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The apparent Michaelis constant, K(M), for glutamate oxidase (GluOx) immobilised on Pt electrodes increased systematically with enzyme loading. The effect was due, at least in part, to electrostatic repulsion between neighbouring oxidase molecules and the anionic substrate, glutamate (Glu). This understanding has allowed us to increase the Glu sensitivity of GluOx-based amperometric biosensors in the linear response region (100+/-11 nA cm(-2)microM(-1) at pH 7.4; SD, n=23) by incorporating a polycation (polyethyleneimine, PEI) to counterbalance the polyanionic protein. Differences in the behaviour of glucose biosensors of a similar configuration highlight a limitation of using glucose oxidase as a model enzyme in biosensor design.
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Affiliation(s)
- Colm P McMahon
- UCD School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
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HIRANO A. Development of Biosensing Methods for Extracellular Neuronal Messengers and Their Application to In Situ Detection in Acute Brain Slices. BUNSEKI KAGAKU 2006. [DOI: 10.2116/bunsekikagaku.55.535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Ayumi HIRANO
- Division of Neurophysiology, National Institute for Medical Research
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Dale N, Hatz S, Tian F, Llaudet E. Listening to the brain: microelectrode biosensors for neurochemicals. Trends Biotechnol 2005; 23:420-8. [PMID: 15950302 DOI: 10.1016/j.tibtech.2005.05.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 04/19/2005] [Accepted: 05/24/2005] [Indexed: 10/25/2022]
Abstract
Chemical signalling underlies every function of the nervous system, from those of which we are unaware, for example, control of the heart, to higher cognitive functions, such as emotions, learning and memory. Neurotransmitters and neuromodulators mediate communication between neurons and between neurons and non-neural cells such as glia and muscle. In the past, the means for studying the production and release of these signalling agents directly has been limited in its temporal and spatial resolution relative to the dynamics of chemical signalling and the structures of interest in the brain. Now microelectrode biosensors are becoming available that give unprecedented spatial and temporal resolution, enabling, for the first time, direct measurement in real time of the chemical conversations between cells in the nervous system.
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Affiliation(s)
- Nicholas Dale
- Warwick Biosensors Group, Department of Biological Sciences, The University of Warwick, Coventry, CV4 7AL, UK.
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Nakamura N, Negishi K, Hirano A, Sugawara M. Real-time monitoring of L-glutamate release from mouse brain slices under ischemia with a glass capillary-based enzyme electrode. Anal Bioanal Chem 2005; 383:660-7. [PMID: 16158299 DOI: 10.1007/s00216-005-0033-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 07/12/2005] [Accepted: 07/18/2005] [Indexed: 11/28/2022]
Abstract
Real-time monitoring of L-glutamate release from various neuronal regions of mouse hippocampal slices under ischemia (a glucose-free hypoxia condition) is described. A glass capillary microelectrode with a tip size of approximately 10 microm containing a very small volume ( approximately 2 microL) of a solution of glutamate oxidase (GluOx) and ascorbate oxidase was used. First, the amperometric response behavior of the electrode at 0 V versus Ag/AgCl was characterized with a standard glutamate solution in terms of continuous measurements, effect of oxygen, viscosity of solution and concentration dependence. The electrode was applied to the real-time monitoring of L-glutamate released from different neuronal regions of acute hippocampal slices submerged in a hypoxia solution. The time-resolved amounts of L-glutamate released at various neuronal regions (CA1, CA3 and DG) of mouse hippocampal slices were quantified and compared with the reported L-glutamate fluxes using difference-image analysis during ischemia.
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Affiliation(s)
- Naoto Nakamura
- Department of Chemistry, College of Humanities and Sciences, Nihon University, Sakurajousui, Setagaya, Tokyo 156-8550, Japan
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Kitade T, Kitamura K, Takegami S, Miyata Y, Nagatomo M, Sakaguchi T, Furukawa M. Needle-Type Ultra Micro Silver/Silver Chloride Reference Electrode for Use in Micro-Electrochemistry. ANAL SCI 2005; 21:907-12. [PMID: 16122159 DOI: 10.2116/analsci.21.907] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A needle-type ultra micro silver/silver chloride reference electrode having a micro capillary with outer and inner diameters of 1.0 microm and 0.5 +/- 0.2 microm, respectively, was constructed. This micro reference electrode can be stuck into a living cell, and is applicable to use in very small environments, such as an electrochemical cell of an electrochemical scanning tunneling microscope or the detection portion of a micro-TAS. Excellent stability and repeatability of the micro reference electrode potential could be obtained by filling the micro capillary with agar gel containing 3.33 mol/L potassium chloride as a salt bridge, by covering the bare part of the silver wire on which silver chloride was deposited, and by electromagnetic shielding of the measurement cell and wire lead from the electromagnetic waves. The electrode showed stable potential for 7 days after its fabrication using 3.3 mol/L potassium chloride aqueous solution containing silver chloride as an internal electrolyte solution. The electrode exhibited constant electrode potential and excellent stability in test solutions of pH 5-9. The electrode potential of a commercial pH glass electrode measured against the micro reference electrode in standard pH buffer solutions was in good accordance with the Nernst equation.
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Affiliation(s)
- Tatsuya Kitade
- Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
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