BUNSEKI KAGAKU
Print ISSN : 0525-1931
Volume 69, Issue 12
Displaying 1-13 of 13 articles from this issue
Review Paper
  • Yumeki TANI, Takashi KANETA
    Article type: Review Paper
    2020 Volume 69 Issue 12 Pages 665-672
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    We demonstrated the utility of optical pressure in the manipulation of oil droplets and vesicles in the field of analytical chemistry. In order to realize chemical analysis in a limited small space, a method to capture and coalesce two oil droplets was developed using two laser beams. Three types of stabilizers for the formation of oil droplets were explored to achieve the coalescence of two droplets whereas polyethylene glycol (PEG) was the most suitable one among them. When using the oil droplets with PEG, the increase in temperature of the medium induced successful coalescence of two droplets. We also developed a method to collect liposomes, which are a model of artificial extracellular vesicles, using optical pressure. It was found that the collection efficiency was significantly improved by adding gold nanoparticles into the solution. This effect is due to thermal convection induced by the optical absorption of gold nanoparticles in solution and an enhancement of the optical pressure caused by binding between the vesicles and the gold nanoparticles. It was also elucidated that the binding was strongly related to the electrostatic interaction in addition to the hydrophobic interaction. Based on these findings, we achieved the collection of nanometer-sized vesicles and exosomes released by cells by optical pressure.

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  • Masaru ARAI, Yuko NISHIMOTO
    Article type: Review Paper
    2020 Volume 69 Issue 12 Pages 673-678
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    As functional water, a dilute aqueous solution of alkali chloride was taken up. Analysis of electrolyzed water produced by electrolysis, and separation/concentration system using water above the eutectic point and below 0 °C were introduced. Electrolyzed water has a bactericidal effect due to the action of generated hypochlorous acid, but it has been shown that active oxygen other than hypochlorous acid is involved in the bactericidal action. It was also found that KCl contributes more to active oxygen than NaCl due to the influence of the alkali metal ions of the salt used as an electrolysis aid. A further investigation of suitable preparation methods for the application is required. We are developing a system that can separate and concentrate inorganic cations and small organic molecules by keeping the aqueous solution of alkali chloride at –10°C, which is higher than the eutectic point of alkali chloride and water and lower than the melting point of water. We are proceeding with a further research as an environmentally friendly analytical method that does not use harmful chemical substances.

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Research Papers
  • Masayori SUWA, Akira UOTANI, Satoshi TSUKAHARA
    Article type: Research Papers
    2020 Volume 69 Issue 12 Pages 679-684
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    Magnetically induced linear dichroism in a suspension of magnetic nanoparticle (MNP) reflects the rotational motion of the MNP. This phenomenon should be useful to measure the local viscosity around the MNP. In this study, we investigated the influence of the viscosity of an MNP suspension on the linear dichroism, and then a couple of robust parameters for viscosity measurements were found. We measured the polarizing angle change in an MNP suspension in a damped oscillating magnetic field (DOMF). Just after the application of DOMF, the polarizing angle change increased. The oscillation of the polarizing angle, whose frequency was twice that of DOMF, was observed. We focused on the amplitude and the phase of this oscillation. The amplitude of the polarizing angle decreased with an increase in the viscosity, and the variation can be fitted with a linear fractional function. The amplitude also depends on the MNP concentration. This fact is undesirable for local viscosity measurement because it is difficult to estimate the precise concentration of MNP in a sample, such as a biological cell. We found the proportionality between the amplitude and the peak value of the polarizing angle change. The proportional coefficient had a similar dependence on the viscosity to the amplitude, but it did not depend on the MNP concentration. Therefore, this proportional coefficient seems to be useful for viscosity measurement. The phase of the polarizing angle change increases with the viscosity and does not depend on the MNP concentration. Since the phase varied with the field amplitude, it is expected that the use of an ac magnetic field with constant amplitude and a lock-in amplifier makes the viscosity measurement sensitive and precise.

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  • Yurie TANI, Yuta YAMAGUCHI, Haruhi YOKOTA, Hirofumi YAMADA, Naofumi OH ...
    Article type: Research Papers
    2020 Volume 69 Issue 12 Pages 685-692
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    We applied wavelength-dispersive XRF (WDXRF) analysis to estimate the fertilizer contents in soil from a single field. Each soil sample was just made into a pellet and measured by WDXRF combined with the Fundamental Parameters approach with good precision within 9 min. Ninety-nine soil samples were collected from a field of approximately 10 ha in the Spring and 51 soil samples were collected in the Fall to determine the fertilizer contents in the soil, i.e., the quantity of phosphorus, potassium, magnesium, and calcium, through WDXRF and conventional analytical methods. The results for phosphorus, potassium, and magnesium showed strong positive correlations between the two methods, while calcium showed a weak negative correlation. The fertilizer contents estimated through the obtained regression lines and WDXRF quantification results indicated that 78 %–96 % of the sampling sites wherein all four elements that were detected were within an error of ±25 % of the measured values. Compared with the conventional diagonal soil sampling method for determining the concentration of fertilizer contents, through WDXRF analysis, distribution of the fertilizer contents was more quickly and efficiently determined and the planar resolution was improved.

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  • Arinori INAGAWA, Nobuo UEHARA
    Article type: Research Papers
    2020 Volume 69 Issue 12 Pages 693-706
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    The RGB-based reproducing method for absorption spectra was applied to colorimetric analysis with smartphone-captured digital color images. The present study demonstrates the reproduction of the spectra of aqueous potassium permanganate coexisting with glucose under a basic condition, phenol red solutions under various pH conditions, and aluminum-eriochrome cyanine R complexes coexisting with cationic surfactants. The reproduced absorption spectra were coincided with the spectra obtained by conventional spectrophotometry with high accuracy. We also applied the present method to water quality tests of environmental water samples, which determined chemical oxygen demand values, pH values and the cationic surfactant concentration. We have confirmed that absorptions spectra were also reproduced even with the environmental water samples. Moreover, the results obtained from the reproduced spectra were almost identical to those obtained from the spectrophotometric spectra, showing the potential of the present method for on-site ratiometric analysis with smartphones. The present method would enable the smartphone-based ratiometric analysis without any monochromatizing equipment such as gratings and imaging spectrometers.

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  • Seiya NAGAO, Masaki KANAMORI, Shinya OCHIAI
    Article type: Research Papers
    2020 Volume 69 Issue 12 Pages 707-714
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    Radioactive and stable carbon isotopes (14C and 13C) can serve as powerful tools for studying the dynamics of organic matter in aquatic systems. This study considered the transport of particulate organic matter in a river system, a main river and its tributary with different watershed conditions, using carbon isotopic signatures. The Kuzuryu River system is located at Fukui and Gifu Prefecture in the central part of Japan, and consists of a main river, Kuzuryu River, and its main tributary, the Hino River. River research was conducted at a fixed station in the lower reaches of both rivers during June to October in 2010. Suspended solid samples were collected from 85 L to 141 L of river water using a continuous-flow centrifugation. δ13C of organic matter in riverine suspended solids had –26.3‰ to –24.0‰ for the Kuzuryu River and –27.0‰ to –26.1‰ for the Hino River. The Δ14C values of the Kuzuryu and Hino samples were –168‰ to –87‰ and –209‰ to –143‰, respectively. The Δ14C values of Hino River were depleted in 14C rather than the Kuzuryu River. However, the carbon isotopes have correlations with the water level for both rivers. The differences in the particulate organic matter characteristics are explained by the distribution of paddy fields and forests in each watershed, and the differences in the supply of suspended solids from their watershed due to rainfall.

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Technical Papers
  • Meri NAKAJIMA, Akihiko ISHIDA, Manabu TOKESHI, Hisashi SATOH
    Article type: Technical Papers
    2020 Volume 69 Issue 12 Pages 715-722
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    Analysis of bacteria in the sewage wastewater treatment process is essential for process stabilization and upgrading. Although bacteria are currently being analyzed by molecular biology techniques targeting the 16S rRNA gene, there is a problem that they are time-consuming and labor-intensive. In this study, we developed a paper-based analytical chip by using two types of DNA molecules that specifically bind to bacterial 16S rRNA. We optimized the fabrication method of the detection probe and the paper-based analytical chip, and then detected synthetic DNA having a nucleotide sequence that hybridizes with the designed DNA molecules and bacterial 16S rRNA extracted from an activated sludge sample. We evaluated the amount of nucleic acids quantitatively by taking images of the detection line on the paper-based analytical chip with a smartphone and analyzing its brightness with an open-source image processing program, ImageJ. Our method was able to detect 85 nM of bacterial 16S rRNA concentration in the extract. Nucleic acids that did not hybridize with either of the designed DNA molecules were not detected, demonstrating high selectivity of our method.

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  • Yumi YOSHIDA, Emi KUSAKABE, Mei TAKAMI, Kohji MAEDA
    Article type: Technical Papers
    2020 Volume 69 Issue 12 Pages 723-730
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    A conducting polymer works as an ion-to-electron transducer in which its redox reaction involves doping/undoping ions, and the conducting polymer-coated electrode has been studied as an inner reference electrode in all-solid ion-selective electrodes, all-solid ISE. Recently, some conducing polymer-inks have been utilized for a disposable printing all-solid ISE. However, the low stable and low reproducible electrode potential in a conducting polymer-coated electrode have been a long-standing problem for practical applications. Our previous work has reported that the partially 50 % oxidized conducting polymer in applying the formal potential has the most redox buffer capacity and shows stable electrode potential. In the present work, two commercially available poly(3,4-ethylenedioxythiophene), PEDOT, inks were examined to evaluate the formal potentials and the oxidation ratio based on the ultraviolet-visible absorption spectra recorded in applying a potential. Principal component analysis (PCA) was useful for extracting the potential-depending spectra from absorption spectra involving the other component’s absorption.

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Notes
  • Takuya KUBO, Seiya KATO, Asako SHIMODA, Raga ISHIKAWA, Shin-ichi SAWAD ...
    Article type: Notes
    2020 Volume 69 Issue 12 Pages 731-735
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    An exosome is one of the extracellular vesicles containing specific proteins, nucleic acids, and sugars. A number of recent reports have shown that exosomes contribute to transporting functions among cells. To facilitate the exosome studies, we focus on the specific separation of exosomes by the recognition of sugar chains on the surface of exosomes. As a typical separation based on sugar chains, lectin affinity chromatography (LAC) which is currently used to purify glycoproteins, is usually employed. However, the pore size of the LAC packing material is fairly small, so that the use of such materials is not suitable for the separation of exosomes having over 100 nm in diameter. To achieve an effective exosome separation, a spongy monolith (SPM), which consists of poly(ethylene-co-glycidyl methacrylate) (PEGM), is expected as a separation medium for LAC. In this study, we prepared two kinds of LAC columns made of the SPMs, immobilized with sambucus sieboldiana agglutinin (SSA) or concanavalin A (ConA). As results, glycoproteins (transferrin and glucose oxidase) were effectively interacted with their respective lectins. Along with glycoproteins, mannose-integrated liposomes were also interacted and rapidly desorbed using the ConA-immobilized SPM (ConA-SPM). Finally, the ConA-SPM was employed for the separations of exosomes, and then the exosomes after passing through the ConA-SPM represented different glycan profiles against the original sample. These results suggest that the lectin-immobilized SPMs will be useful for the separation of exosomes based on the recognition of the surface sugar chains.

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  • Yuta TANAKA, Yui KOHAKU, Shoji ISHIZAKA
    Article type: Notes
    2020 Volume 69 Issue 12 Pages 737-740
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    When micrometer-sized water droplets are levitated in air, thermodynamic metastable states are stable for a long time because they are not affected by the solid surface that provides a scaffold for nucleation. Therefore, it is expected that the use of aerosol droplets as a microreactor would allow chemical processes that are different from those under thermal equilibrium to proceed. The purpose of this study is to construct a double-beam laser trapping system to simultaneously manipulate two water droplets in air, and then to contact and fuse the droplets at an arbitrary timing. Using this system, the effect of surface charge was investigated when water droplets coalesce in air.

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  • Karin MIURA, Sachiko IDE, Toyohiro NAITO, Taisuke SHIMADA, Takao YASUI ...
    Article type: Notes
    2020 Volume 69 Issue 12 Pages 741-746
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    Fine particulate matter sized 2.5 μm or less, referred to as PM2.5, causes serious air pollution in urban cities and is responsible for several health problems, such as respiratory disease and asthma in urban populations. Although seasonal Asian dust, called Kosa (∼ 5 μm), has been extensively studied for over decades, and has been shown to be an allergen in Japan, the influence of PM2.5 on human health has remained unclear due to the intrinsic chemical and biological complexity of isolating variables for study. In this study, PM2.5 was collected at Ito Campus in Kyushu University, Fukuoka, located in extreme western Japan and its physical and biological characteristics were analyzed. The presence of bacteria, Firmicutes genus Bacillus, Lysinibacillus, Paenibacillus, Gracilibacillus, and Solibacillus in the collected PM2.5 sample was confirmed by culturing and conducting DNA sequencing of their 16S rRNA gene.

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Analytical Reports
  • Nobutake NAKATANI, Kohei ICHIZAWA, Ryo MIYASHITA, Takumi KIUCHI, Tomoh ...
    Article type: Analytical Reports
    2020 Volume 69 Issue 12 Pages 747-752
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    In order to clarify the cause of hypereutrophication in Lake Miyajima-numa, one of the Ramsar Convention on Wetlands in Japan, water quality monitoring and dilution bioassay were conducted to determine the seasonal changes of the water quality and the limiting nutrients for phytoplankton growth in this lake. It was confirmed that the chlorophyll a concentration in the lake was high during the time when the white-fronted goose (Anser albifrons) flew in and decreased after it flew away. From the results of a dilution bioassay, it was shown that the limiting nutrient changed from nitrogen to phosphorus during the rapid growth of phytoplankton from late summer to autumn. This suggests that the direct load of ammonium nitrogen leaching from the excrement of geese on the lake was occurred, and then, that the growth of phytoplankton was promoted with the increase of ammonium-nitrogen concentration in water. After that, an excessive supply of ammonium nitrogen from the excrement of geese made phosphorus a limiting nutrient. These results could be useful for the conservation and regeneration of the water quality of Lake Miyajima-numa with appropriate management of migratory waterfowl to reduce nutrient loads in the future.

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  • Takayuki KAWAI
    Article type: Analytical Reports
    2020 Volume 69 Issue 12 Pages 753-757
    Published: December 05, 2020
    Released on J-STAGE: April 04, 2021
    JOURNAL FREE ACCESS

    Recently, single-cell analysis methods, such as fluorescence-activated cell sorting and single-cell transcriptome analysis, have been employed in many biological studies in order to elucidate the characteristics of each cell. So far, genome, transcriptome, proteome, and metabolome analyses have been achieved on the single-cell scale. Single-cell metabolome analysis was usually carried out with mass spectrometry (MS); however, no standard metabolome method has been reported that has sensitivity, quantitation/qualification reliability, and analytical robustness. To address this issue, we focused on capillary electrophoresis (CE)-MS, which has great quantitative reliability, but poor sensitivity. In order to improve the sensitivity, an online sample preconcentration method, large-volume dual preconcentration by isotachophoresis and stacking (LDIS) was applied. Up to 750-fold sensitivity improvement was achieved in the analysis of 20 standard amino acids. A sensitive and robust sheathless ionization emitter that has a thin-walled conductive segment and a flat outlet end was also employed. As a result, an ultra-sensitive metabolome analysis with up to 800 fmol L−1 limit of detection was achieved. Finally, a single MCF-7 cell was analyzed by LDIS-CE-MS, where totally 42 metabolites were identified. This ultra-sensitive and robust metabolome analysis method is promising for next-generation single cell metabolome analysis.

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