BUNSEKI KAGAKU
Print ISSN : 0525-1931
Volume 64, Issue 1
Displaying 1-9 of 9 articles from this issue
Annual Topic “Bio” : Accounts
  • Naoki SASAKI
    Article type: Annual Topic “Bio” : Accounts
    2015 Volume 64 Issue 1 Pages 1-8
    Published: January 05, 2015
    Released on J-STAGE: January 31, 2015
    JOURNAL FREE ACCESS
    AC electrokinetics is concerned with an induced motion of particles and fluids under nonuniform AC electric fields in microscale. The physicochemical nature of this phenomena, which cannot be observed in macroscale, is of great interest. In addition, AC electokinetics can be easily induced by the use of microelectrodes, which can be easily integrated into microchannels. In this paper, applications are described of AC electrokinetics as unit operations in bioanalysis on a microchip. AC electrokinetic fluid flow was utilized to mix fluids in a short time. The principle of cloud point extraction was combined with AC electrokinetics to concentrate membrane-associated biomolecules in a microchannel. These operations will contribute to the functionalization of microchip for bioanalysis.
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Annual Topic “Bio” : Notes
  • Yukihiro OKAMOTO, Ayato HIBINO, Noritada KAJI, Manabu TOKESHI, Yoshino ...
    Article type: Annual Topic “Bio” : Notes
    2015 Volume 64 Issue 1 Pages 9-13
    Published: January 05, 2015
    Released on J-STAGE: January 31, 2015
    JOURNAL FREE ACCESS
    The importance of micro RNA analysis has been significantly increasing because the role of micro RNA in the human body has been gradually revealed. Despite its importance, the analysis has suffered from several troublesome pretreatments, which hamper any easy analysis. Therefore, an easy and high-throughput pretreatment method has been demanded. In this paper, we focused on the great advantages of microchip pretreatments over conventional manual pretreatments and developed a microchip for micro RNA extraction. To simplify microchip fabrication, we adopted poly(dimethyl siloxane) (PDMS) microchip and a silica membrane, which has rolls in RNA extraction fields. With silica membranes and the adhesion nature of PDMS, we could easily fabricate RNA extraction fields in the microchip. With this microchip, we successfully extracted micro RNA from cancer tumor cells. Though this is a preliminary experiment, and still has many improvement points, our device is expected to be applied for easy and fast micro RNA extraction from biological samples.
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Annual Topic “Gold” : Accounts
  • Tohru TAKARADA, Mizuo MAEDA
    Article type: Annual Topic “Gold” : Accounts
    2015 Volume 64 Issue 1 Pages 15-23
    Published: January 05, 2015
    Released on J-STAGE: January 31, 2015
    JOURNAL FREE ACCESS
    Gold naoparticles densely functionalized with a DNA duplex undergo rapid and spontaneous aggregation in a medium of relatively high ionic strength. This non-crosslinking aggregation occurs irrespective of the particle size and the DNA length, while it exhibits both greater temperature- and salt concentration-dependence than that of DNA duplex formation. Interestingly, no aggregation takes place under the same conditions when the DNA duplex has a single-base mismatch at the distal end, which is located at the outermost surface of the particle. In this review, we describe applications of the DNA-carrying gold nanoparticles to gene diagnosis and chemical sensing, with emphasis placed on some attempts to improve the sensitivity.
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Research Papers
  • Hirotaka NAITOH
    Article type: Research Papers
    2015 Volume 64 Issue 1 Pages 25-34
    Published: January 05, 2015
    Released on J-STAGE: January 31, 2015
    JOURNAL FREE ACCESS
    A liquid chromatography/tandem mass spectrometric (LC-MS/MS) procedure for the determination of four tetracycline antibiotics [chlortetracycline (CTC), tetracycline (TC), oxytetracycline (OTC) and doxycycline (DC)] and iso-chlortetracycline (iso-CTC) of CTC metabolite in water samples has been developed. The target analytes in a water sample were solid-phase extracted by the use of a hydrophilic-lipophilic balance cartridge, which were then determined by LC-MS/MS. The combination of the addition of disodium ethylenediaminetetraacetate (EDTA-2Na) as a metal chelation agent to the water sample and elution by back-flushing with methanol/water with 0.1% formic acid (1 : 1, v/v) from the cartridge resulted in quantitative recoveries by solid-phase extraction. The mean recoveries in water samples ranged from 80 to 106% (c.v. 1.9 – 9.0%), and the method detection limits were between 2.8 and 6.2 ng L−1. It was found that this method enables the reliable determination of tetracycline antibiotics and iso-CTC of CTC metabolite residues in water samples at the ng L−1 level. Furthermore, to confirm the derivation of iso-CTC from CTC in an aquatic environment, recovery tests of CTC added to water samples were conducted using this determination method. The results showed that some of the CTC in aquatic environment are converted into iso-CTC, which is affected by a water matrix less than CTC, indicating that iso-CTC is likely to remain in the aquatic environment.
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Technical Papers
  • Gaku KASAHARA, Shunsuke KASHIWAKURA, Kazuaki WAGATSUMA
    Article type: Technical Papers
    2015 Volume 64 Issue 1 Pages 35-41
    Published: January 05, 2015
    Released on J-STAGE: January 31, 2015
    JOURNAL FREE ACCESS
    Laser-induced breakdown plasma-optical emission spectrometry in a single-shot scanning mode was fundamentally investigated to obtain spatially-resolved information on the distribution of inclusion particles. A main target of this measurement was various oxide particles, such as alumina, in the metallugical structure of steel materials. Irradiation of a laser beam having high power density can cause target atoms to be ablated into the laser-induced plasma, where they are excited and eventually emit their characteristic radiation. By scanning the laser beam as well as repeating the laser shots, one can observe variations in the emission intensities of analyte particles, thus enabling the three-dimensional distribution to be in-situ obtained without any complicated pre-treatment. When small amounts of alumina fine particles dispersed and embedded in copper matrix were employed as a test specimen, several experimental conditions, such as a focus of the laser beam and replicates of the scan, were optimized to better the spatial resolution in this measurement.
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  • Keizo KAWASE, Kiwao KADOKAMI
    Article type: Technical Papers
    2015 Volume 64 Issue 1 Pages 43-50
    Published: January 05, 2015
    Released on J-STAGE: January 31, 2015
    JOURNAL FREE ACCESS
    Since the number and volume of the chemical substances that we use has been increasing rapidly, effective tools are necessary to examine not only regulated chemicals, but also unregulated chemicals for evaluating the safety of foods and the environment and to investigate the causes of environmental pollution accidents. There are two conventional techniques to identify unknown substances in samples by GC/MS: mass spectra library search and automated identification and quantification system with a newly developed database (AIQS-DB). However, there are some restrictions in both techniques: a mass spectra library search needs standard substances for confident identification, and AIQS-DB needs a specific instrument. In this study, we investigated a novel target screening system for GC―MS by which every GC―MS on the market can certainly identify a large number of substances registered in a database without the use of standards. The developed system is composed of a freeware, "Automated Mass Spectral Deconvolution and Identification System" provided by National Institute of Standards and Technology and two private libraries [programed temperature retention indices (PTRI) and mass spectra]. By using n-alkanes as PTRI, under the same GC condition, the retention times of the chemicals in samples were exactly predicted with an error for less than 3 s in three different instruments from different GC/MS makers. From accurate predictions of the retention times and mass spectra, reliable identification was achieved with different instruments. Although the number of chemicals registered in the database is only 1000, since substance registration to the private libraries is easy, we can register thousands of substances in the database for achieving various purposes, such as finding causes of environmental pollution, evaluating the safety of foods and the environment and finding illicit drugs.
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Notes
  • Taichi YAMAZAKI, Toshifumi MIYAWAKI, Mari SUGIHARA, Masahiko NUMATA
    Article type: Notes
    2015 Volume 64 Issue 1 Pages 51-54
    Published: January 05, 2015
    Released on J-STAGE: January 31, 2015
    JOURNAL FREE ACCESS
    Since quantitative values on the basis of a nucleus can be obtained by nuclear magnetic resonance (NMR) spectroscopy, the quantitative NMR technique requires no identical standard. For this reason, it is expected to be a universal quantitative method. However, the quantification using an NMR requires a high resolution NMR spectrometer in NMR measurement. In this paper, we discuss the quantitative NMR method using a benchtop NMR spectrometer with a low magnetic field. We studied the conditions of NMR measurement and data process. The precision of the result was evaluated with approximately 1% using a benchtop spectrometer. Especially, the low S/N and large FWHS of the NMR signals caused low repeatability.
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Analytical Reports
  • Tsutomu YOSHIDA, Shigehisa UCHIYAMA, Yutaka TAKEGUCHI, Keiji MIYAMOTO, ...
    Article type: Analytical Reports
    2015 Volume 64 Issue 1 Pages 55-63
    Published: January 05, 2015
    Released on J-STAGE: January 31, 2015
    JOURNAL FREE ACCESS
    Gaseous chemical compounds such as carbonyls, volatile organic compounds (VOC), acid gases, basic gases, and ozone were measured in indoor and outdoor air of 40 houses throughout Sapporo city in the winter (January to March, 2012 and 2013) and summer (July to September, 2012) using four kinds of diffusive samplers. Almost all compounds in indoor air were present at higher levels in the summer than in the winter. The indoor concentrations of acetaldehyde and p-dichlorobenzene exceeded the Health, Labour and Welfare, Japan guideline in three and two houses, respectively. The mean concentrations of formaldehyde were 27 μg m−3 in the summer and 17 μg m−3 in the winter, and showed that the summer concentration was 1.6-fold higher than that in the winter. Nitrogen dioxide was present in extremely high concentrations in the winter, and it was suggested that the sources of nitrogen dioxide in indoor air are kerosene heaters, unvented gas stoves and heaters. Formic acid was generated by combustion because the nitrogen dioxide concentration in indoor air was well correlated with the formic acid concentration (correlation coefficient = 0.947). In outdoor air, the negative correlation between nitrogen dioxide and ozone was observed during the winter. It was suggested that the reaction of nitric oxide and ozone may influence the formation of nitrogen dioxide.
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