Riichiro Nakajima

Doshisha University, Kioto, Kyōto, Japan

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Publications (86)199.66 Total impact

  • Kazuhiko Tsukagoshi, Takahiro Saito, Riichiro Nakajima
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    ABSTRACT: A microchip including two micro-channels for electrophoretic flow and one micro-flow line for pumping flow was designed for the analysis of antioxidants by microchip capillary electrophoresis with a chemiluminescence detection system. The chemiluminescence reaction of luminol with hydrogen peroxide in the presence of Cu(II) catalyst was adopted in the present system, where active oxygen species, such as superoxide radical anions, generates. Nitroblue tetrazolium, superoxide dismutase, and catechin (catechin mixture from green tea) were analyzed as model analytes of antioxidants using the system. Negative peaks from baseline formed by the chemiluminescence reaction were observed based on reaction between active oxygen (superoxide radical anion) and antioxidants (analytes). The components of analytes mixture, nitroblue tetrazolium and superoxide dismutase, were well separated and detected within ca. 2 min. Catechin was also detected around 2 min, resulting in a response curve over the range of 0.1–1 mM. The amounts of catechin in the real samples of commercial green tea beverages were successfully determined.
    Talanta 12/2008; 77(2):514-517. DOI:10.1016/j.talanta.2008.03.026 · 3.51 Impact Factor
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    ABSTRACT: An oxalate reagent-hydrogen peroxide-fluorescent compound chemiluminescence reaction, i.e., peroxyoxalate chemiluminescence, was introduced into micro-channel chemiluminescence analysis (MCCLA) to establish the concept of MCCLA through the direct observation of fluorescence and chemiluminescence using a fluorescence microscope-CCD camera and a microscope-CCD camera. It was confirmed from visual data that chemiluminescence in the MCCLA generated through the liquid-liquid interface collapsed during the course of molecular diffusion in the micro-channel. In addition, the visual data of chemiluminescence were transformed to line drawings on a computer to obtain chemiluminescence profiles. The chemiluminescence profiles were examined in detail at various flow rates and detection points; the relationship between the residence times and the chemiluminescence peak heights, or areas in the profiles, was easily represented as one smoothly changing reaction curve. Furthermore, the fluorescent compounds were detected with high sensitivity and good reproducibility in MCCLA by turning the syringe pumps on and off to produce determinable chemiluminescence signals; a photomultiplier tube was used as a detector. The chemiluminescence intensities in the signals of erythrosine, rhodamine B, Rose Bengal, fluorescein isothiocyanate, and eosin Y were examined; their intensities increased in this order, and eosin Y responded over the range of 1 x 10(-9) - 1 X 10(-6) M with a detection limit of 1 x 10(-9) M (S/N = 3). Introducing of the peroxyoxalate chemiluminescence reaction into MCCLA can extend the analysis system to the analysis of various types of sample and applications incorporating fluorescence labeling techniques.
    Analytical Sciences 11/2008; 24(11):1393-1398. DOI:10.2116/analsci.24.1393 · 1.40 Impact Factor
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    ABSTRACT: Fullerene-containing liposomes with high photosensitization ability were prepared. Disaggregated fullerenes were efficiently injected into the bilayer of liposomes by a phototriggered molecular exchange reaction. These liposomes showed far higher photoreactivity than liposomes thermally produced by heating and microwave irradiation. This result indicates that control of self-aggregation of fullerene leads to a high quantum yield for the photoreaction because of the suppression of self-quenching of photoexcited fullerenes.
    Organic Letters 09/2008; 10(18):4077-80. DOI:10.1021/ol8015918 · 6.32 Impact Factor
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    ABSTRACT: An oxalate reagent-hydrogen peroxide-fluorescent compound chemiluminescence reaction, i.e., peroxyoxalate chemiluminescence, was introduced into micro-channel chemiluminescence analysis (MCCLA) to establish the concept of MCCLA through the direct observation of fluorescence and chemiluminescence using a fluorescence microscope-CCD camera and a microscope-CCD camera. It was confirmed from visual data that chemiluminescence in the MCCLA generated through the liquid-liquid interface collapsed during the course of molecular diffusion in the micro-channel. In addition, the visual data of chemiluminescence were transformed to line drawings on a computer to obtain chemiluminescence profiles. The chemiluminescence profiles were examined in detail at various flow rates and detection points; the relationship between the residence times and the chemiluminescence peak heights, or areas in the profiles, was easily represented as one smoothly changing reaction curve. Furthermore, the fluorescent compounds were detected with high sensitivity and good reproducibility in MCCLA by turning the syringe pumps on and off to produce determinable chemiluminescence signals; a photomultiplier tube was used as a detector. The chemiluminescence intensities in the signals of erythrosine, rhodamine B, Rose Bengal, fluorescein isothiocyanate, and eosin Y were examined; their intensities increased in this order, and eosin Y responded over the range of 1 x 10(-9) - 1 x 10(-6) M with a detection limit of 1 x 10(-9) M (S/N = 3). Introducing of the peroxyoxalate chemiluminescence reaction into MCCLA can extend the analysis system to the analysis of various types of sample and applications incorporating fluorescence labeling techniques.
    Analytical Sciences 02/2008; 24(11):1393-8. · 1.40 Impact Factor
  • Kazuhiko Tsukagoshi, Shingo Ishida, Riichiro Nakajima
    Journal of chemical engineering of Japan 01/2008; 41(2):130-137. DOI:10.1252/jcej.07WE216 · 0.61 Impact Factor
  • Kazuhiko Tsukagoshi, Kazumasa Tsuge, Riichiro Nakajima
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    ABSTRACT: We developed an immune microanalysis system incorporating chemiluminescence detection, where the peroxyoxalate chemiluminescence (CL) detection using bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl]oxalate (TDPO)-hydrogen peroxide (H2O2)-fluorescein isothiocianate (FITC) reaction was newly adopted. The analysis system performed the following three processes on a microchip: immune reaction for high selectivity, electrophoresis for formation and transportation of the sample plug, and CL detection. The immune reaction was carried out using an antibody-immobilized glass bead. The glass bead was placed in one of the reservoirs in the microchip along with antigen (analyte) and a known amount of FITC-labeled antigen to set up a competitive immune reaction. The reactant after the immune reaction was fed electrophoretically into the intersection, resulting in a sample plug. The sample plug was then moved into another reservoir containing TDPO-H2O2 acetonitrile solution. At this point, CL detection was performed. The system described here was capable of determining human serum albumin or immunosuppressive acidic protein as a cancer marker in human serum.
    Analytical Sciences 07/2007; 23(6):739-41. DOI:10.2116/analsci.23.739 · 1.40 Impact Factor
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    ABSTRACT: We developed a capillary electrophoresis with chemiluminescence detection system using 2-methyl-6-p-methoxyphenylethynylimidazopyrazinone as a chemiluminescence reagent for determination of antioxidants of superoxide anions. 2-Methyl-6-p-methoxyphenylethynylimidazopyrazinone reacted with superoxide anions generated through the reaction of hypoxanthine and xanthine oxidase, and then emitted chemiluminescence. Suppression of the chemiluminescence in the presence of antioxidants for superoxide anions was introduced as a detection principle for antioxidants into the capillary electrophoresis with chemiluminescence detection system. After optimizing the analytical conditions, various antioxidants, such as superoxide dismutase, nitroblue tetrazolium, ascorbic acid, and catechin, were subjected to the present system. They gave negative peaks due to the quenching effect; the detection limits of superoxide dismutase, nitroblue tetrazolium, ascorbic acid, and catechin were 1, 100, 100, and 10 microM, respectively (S/N=2). A model sample consisting of superoxide dismutase and nitroblue tetrazolium was satisfactorily separated and detected within ca. 10 min. We also applied the present system to analysis of catechin in green tea as a real sample.
    Analytica chimica acta 04/2007; 589(1):66-70. DOI:10.1016/j.aca.2007.02.039 · 4.52 Impact Factor
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    ABSTRACT: Singlet oxygen was generated by reaction of sodium hypochlorite and hydrogen peroxide in a micro-channel. The two reagent solutions were delivered into the micro-channel by a syringe pump, providing a laminar flow liquid-liquid interface. The chemiluminescence from the singlet oxygen was emitted in the collapse of the interface due to molecular diffusion under laminar flow conditions. The chemiluminescence intensity was observed continuously and stably for each combination of reagents fed into the micro-channel; while, in the normal batch-type reactor the chemiluminescence peaks from singlet oxygen were observed within ca. 5s. The features of the chemiluminescence emitted under laminar flow conditions were examined by changing the concentrations of sodium hypochlorite and hydrogen peroxide; the concentrations of 2.5mM sodium hypochlorite and 7.5mM hydrogen peroxide provided highest chemiluminescence intensities without bubble formation. Also, the effects of beverages, such as green tea, coffee, white wine, red wine, and sake (rice wine), on the chemiluminescence intensity as well as the concentrations of sodium hypochlorite and hydrogen peroxide were examined. The chemiluminescence intensities observed with addition of the beverages to the reagents decreased in the following orders; green tea>coffee>red wine>rice wine>white wine (being added to sodium hypochlorite); coffee>white wine>green tea>red wine>rice wine (being added to hydrogen peroxide). It was found that coffee decreased the chemiluminescence intensity (ca. 33% chemiluminescence decrease) without altering the concentrations of sodium hypochlorite or hydrogen peroxide. The cause of the decrease in chemiluminescence with coffee is discussed.
    Talanta 04/2007; 72(2):607-11. DOI:10.1016/j.talanta.2006.11.022 · 3.51 Impact Factor
  • Kazuhiko Tsukagoshi, Kaori Sawanoi, Riichiro Nakajima
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    ABSTRACT: In our previous study, we developed capillary electrophoresis with an ultraviolet absorption/chemiluminescence dual detection system. Here, to demonstrate one of the possible applications of the capable system as well as confirm the advantage, migration behavior of isoluminol isothiocyanate-labeled alpha-amino acids was examined in the capillary electrophoresis with a dual detection system. The labeled samples were first analyzed by absorption detection with an on-capillary, followed by chemiluminescence detection with an end-capillary. The system easily, rapidly, and simultaneously produced useful information concerning chemiluminescence quenching and amino group-labeling due to the presence of both absorption and chemiluminescence detections.
    Journal of Chromatography A 04/2007; 1143(1-2):288-90. DOI:10.1016/j.chroma.2007.01.037 · 4.26 Impact Factor
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    ABSTRACT: In our previous study, we proposed molecular recognition of mono- and disaccharides making use of the interaction between their diol groups and p-iodophenylboronic acid in capillary electrophoresis with a chemiluminescence detection system. Here, to extend our knowledge of molecular recognition, we first examined the enhancing effects of four phenylboronic acid compounds other than p-iodophenylboronic acid i.e., 4-biphenylboronic acid, 4-octyloxyphenyl-boronic acid, 3-octyloxyphenylboronic acid, and 4-dodecyloxyphenylboronic acid, for luminol-hydrogen peroxide-horseradish peroxidase reaction in the capillary electrophoresis-chemiluminescence detection system. Only 4-biphenylboronic acid showed an enhancing effect similar to that of p-iodophenylboronic acid; the effect was determined over the range of 0.5-10 microM in this system. Second, we estimated the apparent stability constants between the diol groups of saccharides (1-methyl-D-glucoside, D-saccharose, and D-fructose) and the boronic acid moieties of the two enhancers, p-iodophenylboronic acid and 4-biphenylboronic acid. The apparent binding constants obtained here provided insight to confirm the principle of molecular recognition for the saccharides examined here.
    Analytical Sciences 03/2007; 23(2):227-30. DOI:10.2116/analsci.23.227 · 1.40 Impact Factor
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    ABSTRACT: Molecular recognition of mono- and disaccharides was performed making use of the interaction between their diol groups and p-iodophenylboronic acid in capillary electrophoresis (CE) with a chemiluminescence (CL) detection system. p-Iodophenylboronic acid acted as an enhancer for luminol-horseradish peroxidase-hydrogen peroxide CL reaction. p-Iodophenylboronic acid was injected as a sample into the present system to give a CL peak on the electropherogram. The CL intensities were examined using running buffers including mono- and disaccharides. The CL intensities with 1-methyl-D-glucoside, D-saccharose, D-maltose, D-glucose, and D-fructose decreased in this order. The decrease in CL intensity was based on the formation by p-iodophenylboronic acid of cyclic esters with mono- and disaccharides, particularly with those including cis-diol groups. That is, the decrease in CL intensity affected the specific complexation between p-iodophenylboronic acids and saccharides, leading to the molecular recognition of saccharides. We also report separation of a mixture of p-iodophenol and p-iodophenylboronic acid as well as estimation of the apparent binding constant between p-iodophenylboronic acid and saccharides taking advantage of their molecular recognition behavior.
    Journal of Chromatography A 09/2006; 1123(1):106-12. DOI:10.1016/j.chroma.2006.05.003 · 4.26 Impact Factor
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    ABSTRACT: We have developed a compact polytetrafluoroethylene (PTFE) assembly-type capillary electrophoresis with chemiluminescence (CL) detection system. Luminol-microperoxidase-hydrogen peroxide chemiluminescence reaction was adopted. The device is rectangular in shape (60 mm x 40 mm x 30 mm) and includes three reservoirs (sample, migration buffer, and detection reservoirs) with electrodes. The detection reservoir includes an optical fiber to transport light at the capillary tip to a photomultiplier tube. Isoluminol isothiocyanate (ILITC) was analyzed as a model using this device with fused-silica or polytetrafluoroethylene capillary tubes 10 cm in length. We also used the sample reservoir as a reactor for an immune reaction between anti-human serum albumin immobilized on glass beads and isoluminol isothiocyanate-labeled human serum albumin. The present polytetrafluoroethylene assembly with the capillary tube was useful as a palm-sized analysis device for separation and detection, as well as a reactor.
    Journal of Chromatography A 09/2006; 1125(1):144-6. DOI:10.1016/j.chroma.2006.06.101 · 4.26 Impact Factor
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    ABSTRACT: Singlet oxygen was generated by reaction of sodium hypochlorite and hydrogen peroxide in a micro-channel. The two reagent solutions were delivered into the micro-channel by syringe pumps, providing a laminar flow. Such a laminar flow forms a liquid-liquid interface instantly in a micro-channel, and then the interface collapses gradually through molecular diffusion with the residence times. The chemiluminescence from the singlet oxygen was emitted in the course of the collapse of the interface under laminar flow condition. The chemiluminescence intensity was observed continuously and stably in the micro-channel as long as the reagents were fed into the channel. We examined the features of the chemiluminescence emitted in the micro-channel by changing the flow rates of reagents and the detection points in the micro-channel. The data obtained were considered along with the residence times and diffusion lengths. We also examined the effects of antioxidants, such as sodium azide, histidine, nitroblue tetrazolium, and 2-propanol on the chemiluminescence intensity.
    Analytica chimica acta 07/2006; 570(2):202-6. DOI:10.1016/j.aca.2006.04.025 · 4.52 Impact Factor
  • Kazuhiko Tsukagoshi, Kaori Sawanoi, Riichiro Nakajima
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    ABSTRACT: We investigated the complex formation between Cu(II) and human serum albumin (HSA) through a biuret reaction by use of capillary electrophoretic system incorporating an ultra-violet absorption (UV) and chemiluminescence (CL) dual detector. Cu(II)-tartrate complex and Cu(II)-human serum albumin complex were detected by UV detection (282 nm) with on-capillary, followed by CL detection (luminol-hydrogen peroxide CL reaction) with end-capillary. We examined the effects of the reaction time and temperature on the UV and CL responses. On the basis of the obtained results we considered the Cu(II)-human serum albumin complex formation processes and its catalytic activity for the CL reaction. The system easily, rapidly, and simultaneously produced useful information concerning the complex formation of Cu(II) and human serum albumin due to the presence of the both detectors.
    Journal of Chromatography B 05/2006; 833(2):174-8. DOI:10.1016/j.jchromb.2006.01.020 · 2.69 Impact Factor
  • Kazuhiko Tsukagoshi, Kaori Sawanoi, Riichiro Nakajima
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    ABSTRACT: We developed a capillary electrophoretic system incorporating an ultra-violet absorption (UV)/chemiluminescence (CL) dual detector, taking advantage of the CL reaction of luminol-hydrogen peroxide and the batch-type CL detection cell. UV detection was carried out using the on-capillary method while CL detection was performed using the end-capillary method. Examination of isoluminol isothiocyanate (ILITC) as a model sample revealed two main peaks with UV detection and one main peak with CL detection. The first peak in the UV detection data corresponded to the main peak in the CL detection data. We then determined that the ILITC sample included natural ILITC as well as an impurity that had absorption behavior but did not have CL properties and labeling ability. Furthermore, the components of a mixture containing glycine, glycylglycine and glycylglycylglycine, all labeled with ILITC, were well separated and detected using the present system. The present system easily, rapidly, and simultaneously produces useful information due to the presence of both UV and CL detectors.
    Talanta 03/2006; 68(4):1071-5. DOI:10.1016/j.talanta.2005.06.070 · 3.51 Impact Factor
  • Kazuhiko Tsukagoshi, Masayuki Tahira, Riichiro Nakajima
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    ABSTRACT: We developed a capillary electrophoresis (CE) apparatus equipped with a batch- or flow-type bioluminescence (BL) detection cell. Firefly luciferin-luciferase BL reaction was used to analyze samples of nucleotides, such as ATP, dATP, ADP, GTP, UTP, CTP, ITP, and TTP. In the CE apparatus with the batch-type cell, ATP was detected at concentrations of 5-100 microM, while the other nucleotides were not detected at concentrations less than 500 microM. The electropherogram of ATP included two BL peaks; the latter peak showed peculiar broadening, which continued up to ca. 2.5 h. In the CE apparatus with the flow-type cell, ATP, dATP, and ADP were detected with single peaks with detection limits of 1, 75, and 100 microM, respectively. The other nucleotides, GTP, UTP, CTP, ITP, and TTP, were not detected at concentrations less than 0.5 mM. A mixture of 10 microM ATP and 100 microM dATP was examined using the CE apparatus with the flow-type BL detection cell. ATP and dATP were separated using running buffer at pH 10 containing 1 mM phenylboronic acid. The interaction between ATP and phenylboronic acid delayed the migration time of ATP.
    Journal of Chromatography A 12/2005; 1094(1-2):192-5. DOI:10.1016/j.chroma.2005.09.048 · 4.26 Impact Factor
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    ABSTRACT: We have proposed competitive immunoassay using capillary electrophoresis (CE) with a chemiluminescence (CL) detector, in which a small amount of sample (ca. 20 mu L) is required for analysis. Human serum albumin (HSA) and antihuman serum IgG (anti-HSA) were used for immune reaction as a model. A luminol and hydrogen peroxide CL reaction was adopted, and HSA was labeled with isoluminol isothiocyanate (ILITC) for competitive immunoassay. The reactant after the immune reaction was directly subjected to CE with the CL detector, where the labeled HSA was easily and rapidly separated and detected. The amount of labeled HSA indicated a good relationship to that of HSA as an analyte through the immune reaction. The HSA was determined over the range of 0.2-1.2 mu M with a detection limit of 0.1 mu M (S/N = 3). The present method features high sensitivity, a small sample volume, and easy and rapid operation. The method also shows the possibility to analyze a specific protein in a serum sample.
    Bulletin of the Chemical Society of Japan 10/2005; 78(10):1791-1794. DOI:10.1246/bcsj.78.1791 · 2.22 Impact Factor
  • Kazuhiko Tsukagoshi, Naoya Jinno, Riichiro Nakajima
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    ABSTRACT: We developed a micro total analysis system (mu-TAS) incorporating chemiluminescence detection, in which the chemiluminescence reaction of isoluminol isothiocyanato (ILITC) (as a chemiluminescence reagent for labeling)-microperoxidase (as a catalyst)-hydrogen peroxide (as an oxidant) was adopted. The analysis system performed the following three processes on a microchip: immune reaction for high selectivity, electrophoresis for formation and transportation of the sample plug, and chemiluminescence detection for high sensitivity. The three processes were compactly integrated onto the microchip to give the mu-TAS. The microchip contained two microchannels that crossed at an intersection, while the ends of the microchannels accessed four reservoirs. As the first process, the immune reaction was performed using an antibody-immobilized glass bead. The glass bead was placed in one of the reservoirs along with antigen (analyte) and a known amount of ILITC-labeled antigen to set up a competitive immune reaction. For electrophoresis, as the second process, the reactant after the immune reaction was fed electrophoretically into the intersection resulting in a sample plug. The sample plug was then moved into another reservoir containing hydrogen peroxide solution. At this point, chemiluminescence detection was performed as the third process: the labeled antigen mixed with the hydrogen peroxide and the catalyst included in the migration buffer to produce chemiluminescence. Chemiluminescence was detected by a photomultiplier tube located under the reservoir. The mu-TAS described here was capable of determining, with high selectivity and sensitivity, human serum albumin or immunosuppressive acidic protein as a cancer marker in human serum.
    Analytical Chemistry 04/2005; 77(6):1684-8. DOI:10.1021/ac040133t · 5.83 Impact Factor
  • Phosphorus Sulfur and Silicon and the Related Elements 03/2005; 180(5-6):1477-1478. DOI:10.1080/10426500590913203 · 0.83 Impact Factor
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    ABSTRACT: A peak signal due to a chemiluminescence (CL) reaction in a microreactor consisting of a microchannel without sample plug formation is presented. The CL reaction of luminol-hydrogen peroxide-Cu(II) was used in this study. A CL profile, including a peak signal, was observed by the collapse of the liquid-liquid interface based on laminar flow in the microchannel. We examined CL profiles for various flow rates of reagents and detection points in the microreactor. The data obtained were taken into consideration, together with the residence times and diffusion lengths. On the basis of on the measurements of peak height, Cu(II) was determined over the range of 20 nM-0.1 mM with a detection limit of 20 nM (S/N = 3).
    Chemistry Letters 09/2004; 33(9):1178-1179. DOI:10.1246/cl.2004.1178 · 1.30 Impact Factor