Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
ISSN-L : 0910-6340
Volume 28 , Issue 10
Showing 1-16 articles out of 16 articles from the selected issue
Reviews
  • Katsuhiko SATO, Shigehiro TAKAHASHI, Jun-ichi ANZAI
    Type: Reviews
    2012 Volume 28 Issue 10 Pages 929-938
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    We present an overview of the preparation and properties of layer-by-layer (LbL) deposited thin films and microcapsules in relation to their use in the development of biosensors and controlled release systems. Enzyme biosensors can be constructed by immobilizing enzymes on the surface of electrodes by LbL deposition without loss of their catalytic activity. In addition to synthetic polymers, binding proteins, such as avidin and lectin, are also used for constructing LbL films through avidin-biotin and lectin-sugar interactions. The performance characteristics of LbL film-based biosensors can be tuned by controlling the number of layers and by the choice of film components. The permeability of polyelectrolyte LbL films to ions and molecules is discussed in relation to the use of the films for eliminating interference in biosensors. The possible use of polysaccharide LbL film-coated electrodes for the construction of biosensors is highlighted, and examples of LbL film- and microcapsule-based optical sensors are described. We then focus on the use of LbL films and microcapsules as vehicles for controlled release, in particular on recent progress in the controlled release of insulin from LbL films and microcapsules. LbL films composed of insulin and polymers are sensitive to environmental pH, and release insulin in response to pH changes, suggesting that insulin LbL films can be used in the development of orally administered insulin. The construction of glucose-dependent insulin release systems using LbL insulin microcapsules functionalized with phenylboronic acid, lectin, and glucose oxidase is also examined.
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Original Papers
  • Hisao YOSHINAGA, Koji NAKANO, Nobuaki SOH, Toshihiko IMATO
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 939-945
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    An AFM-imaging-based method for single nucleotide polymorphism (SNP) analysis is described. A stem-loop-forming 34-mer oligonucleotide (p34s) was designed. p34s contains the complementary sequence for K-ras (5′-GGT GGC-3′, t6G), one of the human oncogenes, at the 5′-end for target-recognition and five successive phosphorothioate linkages in the loop. The functional probe, either alone or hybridized with target DNA (p34s/t6G), relaxed upon treatment with “opener” DNA. The template/target DNA interstrand hybridization product is covalently connected by ligase if the correct target is used, but not hybridized species including mismatches. With these results, developed was a solid-phase SNP assay by transferring an aliquot of the product onto an Au(111) substrate for self-assembly, followed by AFM imaging. Clear contrasts that allow the detection of SNPs, were observed for the ligated and non-ligated species representing the loop-to-linear conformational change. Simple statistical surface-roughness analysis determined the lowest concentration of the sample to be 5 × 10−10 M, whose necessary sample quantity was 5 fmol.
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  • Mitsuru YASUDA, Takuo AKIMOTO
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 947-952
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    This paper presents highly sensitive fluorescence detections of avidin and streptavidin using an optical interference mirror (OIM) slide consisting of a plane mirror covered with an optical interference layer. Compared with a common glass slide, the OIM slide can enhance the fluorescence from a dye by more than 100-fold. We fabricated an OIM slide by depositing an optical interference layer of Al2O3 on an Ag mirror. To enhance the fluorescence maximally, the optimal thickness of the Al2O3 layer was estimated from optical interference theory. For detections of protein, avidin/streptavidin labeled with fluorescein, Cy3, and Cy5 were detected with biotin immobilized on an OIM slide with the optimal Al2O3 thickness. We achieved a sensitivity improvement of more than 50-fold, comparing with a glass slide. Such a high degree of improvement would be a significant contribution to further progress in biomedical research and medical diagnostics.
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  • Ikuo UETA, Kazuya TAKAHASHI, Yoshihiro SAITO
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 953-957
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    By introducing sequentially connected two packed-capillary columns, a wide range of volatile compounds were successfully separated in gas chromatography. The hyphenation of two packed-capillary columns of 1.0 mm i.d. was accomplished using a conventional 6-port valve, where the temperature of each column was individually controlled in the respective column ovens. These columns were prepared with two different types of sorbents, each having a different selectivity, in order to separate a wide range of compounds, including permanent gases, volatile alcohols and other typical volatile organic compounds. With a simple valve switching operation, the complex sample mixtures were rapidly separated and detected.
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  • Hitoshi KODAMATANI, Akito MATSUYAMA, Keiitsu SAITO, Yuriko KONO, Ryo K ...
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 959-965
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    A sensitive determination method for mercury speciation analysis was developed. Four mercury species, mercury ion, methylmercury, ethylmercury, and phenylmercury, were complexed with emetine-dithiocarbamate (emetine-CS2), and then injected onto a HPLC instrument coupled with a tris(2,2′-bipyridine)ruthenium(III) chemiluminescence detection system. The emetine-CS2 complexing agent was effectively used to measure the concentration in addition to serving as a separation and detection reagent. The calibration curves for these mercury complexes were linear in the range of 0.050 – 10 μg L−1 (as Hg). The limit of detection for (emetine-CS2)2Hg, emetine-CS2-methylmercury, emetine-CS2-ethylmercury, and emetine-CS2-phenylmercury were 30, 17, 21, and 22 ng L−1, respectively. The sensitivity of this method enables the determination of mercury species in water samples at sub-ppb levels. Furthermore, the method was applied to biological samples in combination with acid leaching and liquid–liquid extraction using emetine-CS2 as an extraction reagent. The determination results were in good agreement with the values of the certified reference materials.
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  • Yong-Gang ZHAO, Xiao-Hong CHEN, Shan-Shan YAO, Sheng-Dong PAN, Xiao-Pi ...
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 967-971
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in red wine. The effects of ion-suppressors, i.e., trifluoroacetic acid (TFA) and ammonium acetate (AmAc) on retention behavior of nine food additives in RP-HPLC separation were discussed in detail. The relationships between retention factors of solutes and volume percent of ion-suppressors in the mobile-phase systems of acetonitrile–TFA aqueous solution and acetonitrile–TFA–AmAc aqueous solution were quantitatively established, respectively. The results showed that the ion suppressors had not only an ion suppression effect, but also an organic modification effect on the acidic analytes. The baseline separation of nine food additives was completed by a gradient elution with acetonitrile–TFA(0.01%, v/v)–AmAc(2.5 mmol L−1) aqueous solution as the mobile phase. The recoveries were between 80.2 – 99.5% for all analytes with RSDs in the range of 1.5 – 8.9%. The linearities were in the range of 0.2 – 100.0 mg L−1 with determination coefficients (r2) higher than 0.9991 for all analytes. The limits of quantification (LOQs) were between 0.53 – 0.99 mg L−1. The applicability of the proposed method to detect and quantify food additives has been demonstrated in the analysis of 30 real samples.
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  • Yoshikazu OKA, Shinnosuke NAKAMURA, Yusuke UETANI, Tatsuya MOROZUMI, H ...
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 973-978
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    Fluorescent γ-cyclodextrin derivatives, modified using N-phenyl-x-anthracenecarboxamido (ACs; x = 9, 1), were synthesized and investigated using fluorescence and UV-vis spectroscopy. Fluorescence enhancements of ACs were observed up to 12-fold by the addition of sodium dodecyl sulfate (SDS) below the critical micellar concentration (CMC). In the presence of a nonionic surfactant, such as Triton X-100, fluorescence spectra were scarcely changed. The fluorescence selectivity between SDS and Triton X-100 was clarified from the different spectral behaviors by circular dichroism and 1H NMR spectroscopies.
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  • Ikko MIKAMI, Eri SHIBAYAMA, Manami YUZAWA, Yasuyuki MIURA
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 979-983
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    The effect of ethanol addition on the determination of thiosulfate based on the reduction of Ce(IV) and fluorescence detection of Ce(III) was investigated by flow-injection analysis. It was found that the sensitivity of thiosulfate detection was significantly increased by injecting thiosulfate into a mixed solution of Ce(IV) and ethanol, rather than a solution of Ce(IV) alone. This is probably due to trace amounts of thiosulfate accelerating the rate of reduction of Ce(IV) by ethanol: Ce(IV) is slowly reduced by ethanol in the absence of thiosulfate, and thiosulfate serves as a catalyst to the reduction. The detection limits as S/N = 3 for thiosulfate were very low (10−9 M level).
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  • Yoshio TAKAHASHI, Kazuhiro KONDO, Asami MIYAJI, Miyuki UMEO, Tetsuo HO ...
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 985-992
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    Given that the supply of several rare earth elements (REEs) is sometimes limited, recycling REEs used in various advanced materials, such as Nd magnets, is important for realizing efficient use of REE resources. In the present work, the feasibility of using DNA for REE recovery and separation was examined, along with the identification of the binding site of REEs in DNA. In particular, a DNA-cellulose filter paper hybrid was prepared so that DNA-based materials can be used for the separation of REEs using columns loaded with DNA. N,N′-Disuccinimidyl was used as a cross-linker reagent for the fixation of DNA onto a fibrous cellulose filter. The results showed that (i) the DNA-filter hybrid has a sufficiently high affinity to adsorb REEs; (ii) the adsorption capacity was 0.182 mg/g for Nd; and (iii) the affinity of REEs for DNA was stronger for REEs with larger atomic numbers. The difference of the affinity among REEs in the third result was compared with the adsorption patterns of REEs discussed in the literature. The comparison suggests that phosphate in the DNA-filter paper hybrid was responsible for REE adsorption onto the hybrid. The results were supported by the Nd, Dy, and Lu LIII-edge EXAFS; the REE-P shell was identified for the second neighboring atom, showing the importance of the phosphate site as REE binding sites. The difference in the affinity among REEs suggest that group separation of REEs (such as La, Ce, (Pr and Nd), (Ho, Dy, and Er), (Tb and Gd), (Sm, Eu), Tm, Yb, and Lu) is possible, although complete isolation of each REE from a solution containing all REEs may be difficult. For practical applications, Nd and Fe(III) were successfully separated from a synthetic solution of Nd magnet waste using columns loaded with the DNA-filter hybrid.
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  • Maria Giovanna GUISO, Giancarla ALBERTI, Giovanni EMMA, Maria PESAVENT ...
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 993-999
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    The sorption properties of rice husk towards Cu(II), Cd(II) and Pb(II) were studied. The sorption isotherms are described by the Langmuir equation, and Pb(II) shows a higher affinity for rice husk compared to Cu(II) and Cd(II) under the same conditions. The kinetics of sorption obeys to a pseudo second-order equation for all metals. The sorption profiles as a function of the pH were used to characterize the stoichiometry of the sorption reaction. The competition for metal complexation by any ligand in solution is also accounted for. Upon increasing the ionic strength, the sorption curves of Pb(II) move to basic pH; this shift can be explained by considering the effect of nitrate complexes on the free metal ion concentration, since KNO3 is used as the ionic medium. An attempt to employ rice husk in a dynamic system is presented.
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  • Lei ZHANG, Li-Lin WANG
    Type: Original Papers
    2012 Volume 28 Issue 10 Pages 1001-1007
    Published: October 10, 2012
    Released: October 10, 2012
    JOURNALS FREE ACCESS
    A polyaniline (PAN) network structure was fabricated on a poly(o-aminophenol) (POAP) modified glassy carbon electrode (GCE) by using a three-step electrochemical deposition procedure, and applied to the electro-catalytic oxidation of ascorbic acid (AA) and uric acid (UA). Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) have been employed to investigate the PAN network structure on a POAP modified GCE (PAN-OAP/GCE), which indicated the formation of a 3-dimensional (3D) non-periodic PAN network with good electrical contract and the maintenance of the electro-activity of PAN in neutral and even in alkaline media. Because of its different catalytic effect towards the electro-oxidation of AA and UA, the PAN-OAP/GCE could resolve the overlapped voltammetric response of AA and UA into two sharp and well-defined voltammetric peaks with both CV and differential pulse voltammetry (DPV), which could be applied for the selective and simultaneous determination of AA and UA in their binary mixture. Under the optimum conditions, the calibration curves for AA and UA were in the range of 2.5 – 6200 and 0.5 – 450 μmol L−1 with correlation coefficients of 0.998 and 0.998, respectively. The detection limits (S/N = 3) are 1.4 and 0.3 μmol L−1 for AA and UA, respectively. Besides good stability and reproducibility, the PAN-OAP/GCE also exhibited good sensitivity and selectivity. The proposed method has been applied to the simultaneous detection of AA and UA in human urine with satisfactory result.
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