Yoshiko Arikawa

Highly sensitive quartz crystal immunosensors for multisample detection of herbicides

Abstract A piezoelectric quartz crystal immunosensor was developed for the multisample detection of herbicides in water. The antibodies against triazine derivatives were deposited onto a polystyrene-coated 9 MHz AT-cut quartz crystal resonator. A competitive immuno-reaction method with a protein-labelled antigen was utilized. The resulting frequency change due to the adsorption of protein-labelled atrazine was measured. The atrazine concentration was detectable in the range 0.001 to 1 ng/ml, and the linear correlation could be obtained from 0.01 to 1 ng/ml of atrazine. Several triazine derivatives were tested and found to be detectable owing to the cross-reactivity of the antibody.

An automatic flow-injection analysis system for determining phosphate ion in river water using pyruvate oxidase G (from Aerococcus viridans).

An automated flow-injection system combining a pyruvate oxidase reaction and chemiluminescence for the detection of phosphate ion in river water has been developed. In this research, we used pyruvate oxidase G (PyrOxG), from Aerococcus viridans, immobilizing it on N-hydroxysuccinicacidimido beads without a cross-linker. In this sensor system, which was constructed as a trial system of desktop type, the temperature was precisely controlled. After the sensor system was optimized, a calibration curve was obtained with a detection limit of 96 nM phosphate ion, a range between 96 nM and 32 microM phosphate ion, and a relative standard deviation of 2.3% (n=5) at 25 degrees C. The sensitivity of this sensor was sufficient to determine the maximal permissible phosphate-ion concentration in the environmental waters of Japan (0.32 microM). In addition, the sensor could determine the calibration curves between 0.16 and 32 microM phosphate ion (five points, n=3; averaged correlation, r=1.00) for at least 2 weeks, demonstrating enough stability for practical use. Furthermore, we investigated the influence on the sensor response of dissolved substances in river water such as metal ions, heavy metal ions, inorganic ions, and organic compounds. Treatment with activated carbon could improve the response of the sensor when inhibited by dissolved substances in river water, except for manganese ion and uric acid. The sensor system could determine the concentrations of phosphate ion in various samples of river water from the Tone River. The results obtained by this sensor system and the modified molybdenum blue method were compared, and good correlation (r=0.94) was obtained.

Application of a linear alkylbenzene sulfonate biosensor to river water monitoring

A novel whole cell biosensor was constructed for the detection of anionic surfactants in aquatic environments. The analysis was rapid, convenient and did not require organic reagents. In this report, the application of this sensor to river water samples was investigated when applied to environmental samples; other organic substances present in river water may affect the measurement of linear alkylbenzene sulfonates. In order to deal with this problem, a correction system was developed using whole cells of Trichosporon cutaneum. This system was applied to in situ 24 h continuous monitoring in the Saka river.

Biosensors for environmental control

Abstract Environmental control is very important for its protection. Various kinds of biosensors have been developed and utilized for pollutant detection. The biosensors provide alternatives to conventional methods which have many disadvantages. Some have already been used for real-time monitoring in situ. In this article the importance of the application of biosensors for environmental control is described.

Phosphate Sensor Composed from Immobilized Pyruvate Oxidase and an Oxygen Electrode

Abstract A phosphate sensor based on amperometric determination was constructed with immobilized pyruvate oxidase and an oxygen electrode. A rapid, simple and sensitive determination of phosphate was performed with the sensor. The determination time was 7min. The linearity range of this sensor was 12 – 80μM.

A novel biosensor system for the determination of phosphate

A highly sensitive biosensor system has been developed for phosphate detection. This biosensor system is based on the pyruvate oxidase reaction and a subsequent luminol chemiluminescence reaction. Hydrogen peroxide generated by pyruvate oxidase reacts with luminol catalyzed by an immobilized peroxidase. The resulting chemiluminescence is detected by a photomultiplier. This system uses a flow injection analysis (FIA) system resulting in the rapid determination of phosphate, taking approximately 3 min for one measurement. A linear response was observed from 0.37 μM to 7.4 μM phosphate while the detection limit was 74 nM. This sensitivity is sufficient to determine the maximum permissible phosphate concentration of the natural waters of Japan (0.32 μM). The pyruvate oxidase immobilized column gave a stable response over a period of 2 weeks when stock solutions were analyzed.

Application of nitrite reductase from Alcaligenes faecalis S-6 for nitrite measurement

The enzymatic reaction of nitrite reductase (NIR) from Alcaligenes faecalis S-6 was applied to the measurement of nitrite. NIR was immobilized on the surface of a gold electrode using filter paper and a dialysis membrane, and used as a working electrode in a three-electrode system. Amperometric methods were applied using NIR and the electron mediator 1-methoxy PMS (1-methoxy-5-methylphenazinium methylsulfate). The decrease in cathodic current showed a correlation to nitrite concentration over the range 0-1 mg/l. Measurements using a batch-flow type system gave a lower detection limit of 0.01 mg/l. This is sufficient for the detection of nitrite in natural waters.

Phosphate sensing system using pyruvate oxidase and chemiluminescence detection

Abstract A flow injection phosphate analysis system based on an enzymic reaction and a subsequent luminol chemiluminescence reaction has been developed. The system consists of an immobilized pyruvate oxidase column, mixing chamber for the chemiluminescent reaction and a photomultiplier. The H 2 O 2 generated by the reaction of phosphate and pyruvate oxidase then reacts with luminol and horseradish peroxidase and the consequent chemiluminescence is detected using a photomultiplier. This system is capable of the rapid determination of phosphate, the time required for one measurement cycle being approximately 3 min. A linear response was observed from 4.8 to 160 μM phosphate.

A Novel Microbial Sensor for Anionic Surfactant Determination

Abstract A novel whole cell biosensor was constructed for detection of anionic surfactants in an aquatic environment. The sensor response to linear alkyl benzene sulfonates was linear up to 6 mg l−1 which is a range suitable for the detection of anionic surfactant concentration in polluted river water. Under optimum conditions, the sensor response time was less than 15 min. Anionic surfactant analysis was rapid and convenient and did not require organic reagents which are harmful to an environment.

Development of a highly sensitive chemiluminescence flow-injection analysis sensor for phosphate-ion detection using maltose phosphorylase

A chemiluminescence flow-injection analysis biosensor has been constructed for phosphate-ion detection. This system is coenzymeless and employs a maltose phosphorylase, mutarotase, and glucose-oxidase (MP–MUT–GOD) reaction system combined with an Arthromyces ramosus peroxidase–luminol reaction system. The system consists of a column packed with MP–MUT–GOD immobilized on N-hydroxysuccinimide beads, a mixing joint for the chemiluminescence reaction, and a photomultiplier. The response provided by this system was linear, with a wide range between 10 nM and 30 μM phosphate ion, and a measuring time of 3 min per sample. Under the optimal condition, the sensor was able to detect 1.0 μM phosphate ion for at least 2 weeks. For a practical application, the determination of phosphate ion in river water was examined using ethylenediaminetetraacetic acid, and the results were estimated by comparing with the molybdenum-blue method.