| 1. |
T. Anada, H. Matsunaga, R. Karinaga, K. Koumoto, M. Mizu, K. Nakano, S. Shinkai, and K. Sakuraia, Proposal of new modification technique for linear double-stranded DNAs using the polysaccharide schizopyllan, Bioorganic & Medicinal Chemistry Letters, 10.1016/j.bmcl.2004.08.043, 14, 22, 5655-5659, Vol.14, pp.5655 - 5659, 2004.09, A natural polysaccharide schizophyllan (SPG) has been known to form a stable complex with poly(dA). We attached a poly(dA)(80) tail to the both ends of a linear double-stranded DNA, which had been prepared from a plasmid DNA vector. The poly(dA) tailed DNA verified to form complex with SPG by gel electrophoresis and atomic force microscopy (AFM). AFM images indicated that the complexes exhibit a dumbbell-like architecture, that is, quite similar to that of adenovirus genome. The complex demonstrated excellent exonuclease resistance, probably because of the protection effect by SPG complexation.. |
| 2. |
Ryoichi Ishimatsu, Yoshie Furukawa, Koji Nakano,, Development of a facile time-resolved spectroelectrochemical method: An application to determine the rate constant of protonation for anions of 9,10-diphenylanthracene, biphenyl, and p-quaterphenyl, Journal of Electroanalytical Chemistry, 10.1016/j.jelechem.2022.116684, 921, 116684-116684, 2022.09, Using a conventional three-electrode system and electrochemical cell, we developed a simple spectroelectro-
chemical method that can be used to determine the rate constant of protonation reaction for several reduced
species. A glassy carbon (GC) disk electrode as a working electrode and halogen lamp as a light source were
employed. The reflected light on the GC electrode surface through the diffusion layer of electrochemically gen-
erated species was recorded by an electron multiplying charge coupled device camera equipped with a spec-
trometer. With this system, the absorbance change by the generation of the radical anion of 9,10-
diphenylanthracene (DPA), biphenyl, and p-quaterphenyl was monitored. The molar extinction coefficient
(ε) of the radical ions was calculated with the absorbance and charge during potential steps. The absorption
spectrum of electrochemically generated dianion of p-quaterphenyl was also monitored, and the ε value was
determined. The comproportionation reaction between p-quaterphenyl2− and neutral p-quaterphenyl was also
clearly observed on the spectroelectrochemical data. The absorbance change during the protonation at differ-
ent concentration of ethanol (cEtOH) for DPA•−, biphenyl•−, p-quaterphenyl•−, and p-quaterphenyl2− and the ε
values were used to determine the first-order rate constant of the protonation reaction. The first-order rate con- 2 •− •− 2− 3
stant increased linearly against cEtOH for DPA , p-quaterphenyl , and p-quaterphenyl , and against cEtOH for biphenyl•−. From the slopes, the reaction rate was determined to be 0.45, 4.2×102, and 4.3×104 M−2 s−1, for DPA•−, p-quaterphenyl•−, and p-quaterphenyl2−, respectively, and for biphenyl•−, 6.8×104 M−3 s−1.. |
| 3. |
Naoki Matsuda, Hirotaka Okabe, Toshihiko Nagamura, Koji Nakano, Direct Electron Transfer Reaction of Cytochrome c Immobilized on a Bare ITO Electrode, Bulletin of the Chemical Society of Japan, https://doi.org/10.1246/bcsj.20200192, 94, 2, 433-439, 2021.01, To measure the direct electron transfer (DET) reaction of cytochrome c (Cytc) immobilized on a bare ITO electrode after removing the adsorbed molecules, automated solution exchange (ASE) processes were performed to induce their desorption. By fitting the absorbance decay curve observed at the Soret band peak position of Cytc at around 408 nm during the ASE processes with a double exponential equation, the final immobilized fraction was estimated to be 58.6% of the Cytc adsorbed on bare ITO electrodes under the experimental conditions. Cyclic voltammograms (CVs) of Cytc adsorbed on the bare ITO electrodes were measured for 60 min to elucidate the DET activity of immobilized Cytc. After repeated CV measurements, approximately 90% of immobilized Cytc was found to remain from the evaluation based on the coulombic amount of reduction and oxidation peaks. The scan rate dependent peak separation data from the immobilized Cytc between reduction and oxidation peaks in CVs produced 2.7 times larger DET reaction rate constant than that previously reported for the Cytc adsorbed on the bare ITO electrode.. |
| 4. |
R. Ishimatsu, S. Shimizu, S. Hongsibsong, K. Nakano, C. Malasuk, Y. Oki, K. Morita, Enzyme-linked immunosorbent assay based on light absorption of enzymatically generated aniline oligomer: Flow injection analysis for 3-phenoxybenzoic acid with anti-3-phenoxybenzoic acid monoclonal antibody, Talanta, https://doi.org/10.1016/j.talanta.2020.121102, 218, 121102, 2020.10.  |
| 5. |
Ryoichi Ishimatsu, Shuya Tashiro, Takashi Kasahara, Juro Oshima, Jun Mizuno, Koji Nakano, Chihaya Adachi, Toshihiko Imato, Kinetics of Excimer Electrogenerated Chemiluminescence of Pyrene and 1-Pyrenebutyricacid 2-Ethylhexylester in Acetonitrile and an Ionic Liquid, Triethylpentylphosphonium Bis(trifluoromethanesulfonyl)imide, Journal of Physical Chemistry B, 10.1021/acs.jpcb.9b08813, 123, 50, 10825-10836, 2019.12, We describe the kinetics of excimer electrogenerated chemiluminescence (ECL) of a liquid pyrene derivative, 1-pyrenebutyricacid 2-ethylhexylester (PLQ) dissolved in a molecular solvent, acetonitrile (MeCN), and an ionic liquid, triethylpentylphosphonium bis(trifluoromethanesulfonyl)imide ([P2225][TFSI]). Pyrene was also used for comparison. To discuss the kinetics of the excimer ECLs, the photophysical and electrochemical properties and electronic states of PLQ and pyrene were revealed. The photoluminescence (PL) spectra, rate constants for the radiative transitions, and redox potentials of PLQ and pyrene dissolved in MeCN and [P2225][TFSI] suggest that as a solvent, [P2225][TFSI] behaves more polar than MeCN. By analyzing the PL decay curves, the rate constants to form the excimer were determined to be on the order of 109 and 107 M-1 s-1 in MeCN and [P2225][TFSI], respectively, which were limited by the diffusion. For neat PLQ (1.6 M), a delay of 0.3-0.4 ns for the excimer emission compared to the monomer emission was observed. It is likely that the delay corresponds to the timescale for arranging the conformation to form the excimer. The ECL of PLQ was generated by applying a square wave voltage to produce the radical anion and cation, and on the ECL spectra, the excimer emission was more prevailed compared to the PL spectra. Kinetic analysis for the electron transfer reaction between the radical ions based on Marcus theory indicates that the electron transfer is limited by the diffusion of the radical ions. Moreover, the electron transfer distance (det) between the radical cation and anion to generate excited states was calculated with a framework of the theory. Kinetically, the electron transfer can take place at det et 2225][TFSI]. The density functional theory (DFT) and time-dependent DFT calculations show that the potential energy curve of the excimer against the distance between the pyrene rings reaches a minimum at 3.50 Å. This suggests that through the electron transfer, the process of the direct formation of the monomer S1 state followed by the excimer formation is more prevailed than that of the direct excimer formation.. |
| 6. |
Ryoichi Ishimatsu, Hirosato Shintaku, Yuto Kage, Misaki Kamioka, Soji Shimizu, Koji Nakano, Hiroyuki Furuta, Toshihiko Imato, Efficient Electrogenerated Chemiluminescence of Pyrrolopyrrole Aza-BODIPYs in the Near-Infrared Region with Tripropylamine
Involving Formation of S2 and T2 States, Journal of the American Chemical Society, 10.1021/jacs.9b05245, 141, 30, 11791-11795, 2019.07, Efficient electrogenerated chemiluminescences (ECLs) of three pyrrolopyrrole aza-BODIPYs in the near-infrared region by using tripropylamine as a coreactant are reported. Kinetic analysis based on Marcus theory indicates the direct formation of S2 and T2 states through the electron transfer reaction, which affects the ECL efficiencies.. |
| 7. |
Eri KUNISAWA, Ryoichi ISHIMATSU, Koji NAKANO, and Toshihiko IMATO†, Electrogenerated Chemiluminescence of Tris(dibenzoylmethane)phenanthroline Europium(III) as a Light Source: an Application for the Detection of PO43– Based on the Ion Associate Formation of Phosphomolybdic Acid and Malachite Green, Chemistry Select, https://doi.org/10.2116/analsci.19N003, 35, 7, 799-802, 2019.06, We demonstrate that electorogenerated chemiluminescence (ECL) of an organometallic Eu(III) complex, tris(dibenzoylmethane)phenanthroline europium(III), whose emission spectra is very sharp with the maximum wavelength of 612 nm, can be used as a light source for the detection of PO43– based on changing the absorbance of the ion associate of malachite green (MG+) and phosphomolybdic acid. The ECL was also applied to measure the absorbance of MG+. With the detection system we established, absorbance up to ∼1.6 with a change of ∼0.1 could be detected.. |
| 8. |
Ryoichi Ishimatsu, Eri Kunisawa, Hirosato Shintaku, Koji Nakano, Toshihiko Imato, Portable Analytical Detection Systems Based on Light Emitting Devices, 2019 International Conference on Electronics Packaging, ICEP 2019, 10.23919/ICEP.2019.8733418, 294-297, 2019.04, Portable analytical detection systems based on light emitting devices, organic light-emitting diode (OLED), and electrogenerated chemiluminescence (ECL) are described. The OLED is composed of an Eu(III) complex, whose emission spectrum is very sharp, was applied for fluorescence detection, and ECL of a boron-dipyrromethene derivative showing relatively sharp spectrum was used for the absorbance measurements.. |
| 9. |
Ryoichi Ishimatsu, Eri Kunisawa, Koji Nakano, Chihaya Aachi, Toshihiko Imato, Electrogenerated Chemiluminescence and Electronic States of Several Organometallic Eu(III) and Tb(III) Complexes:Effectsof the Ligands, Chemistry Select, DOI: 10.1002/slct.201900595, 4, 9, 2815-2831, 2019.03. |
| 10. |
Koji Nakano, Takayuki Honda, Kanako Yamasaki, Yoshiki Tanaka, Keiichi Taniguchi, Ryoichi Ishimatsu, Toshihiko Imato, Carbon quantum dots as fluorescent component in peroxyoxalate chemiluminescence for hydrogen peroxide determination, Bulletin of the Chemical Society of Japan, 10.1246/bcsj.20180095, 91, 7, 1128-1130, 2018.01, Nitrogen-doped carbon quantum dots synthesized by onepot, microwave-assisted pyrolysis of citric acid in the presence of a small number of N-doping precursors, 1, 2-ethylenediamine, were found to be involved in the chemically initiated electron exchange luminescence enabling peroxyoxalate chemiluminescence assay of hydrogen peroxide in the concentration range of 101000 μM.. |
| 11. |
Ryoichi Ishimatsu, Hirosato Shintaku, Chihaya Aachi, Koji Nakano, Toshihiko Imato, Electrogenerated Chemiluminescence of a BODIPY Derivative with Extended Conjugation, Chemistry Select, DOI: 10.1002/slct.201702449, 2, 32, 10531-10536, 2017.11. |
| 12. |
Ryoichi Ishimatsu, Yuko Kirino, Chihaya Aachi, Koji Nakano, Toshihiko Imato, Quenching Behavior of Thermally Activated Delayed Fluorescence from a Donor-Acceptor Molecule, 1,2,3,5-Tetrakis(carbazol-9-yl)-4,6- dicyanobenzene by O2, Chemistry Letters, DOI: http://dx.doi.org/10.1246/cl.160561, 45, 10, 1183-1185, 2016.10. |
| 13. |
Jie Zhan, Ryoichi Ishimatsu, Koji Nakano, Toshihiko Imato, Development of Surface Plasmon Resonance Sensor Chip for Multiplex Sample Detection, J. Flow Injection Analysis, https://doi.org/10.24688/jfia.33.1_23, 33, 1, 23-32, 2016.06, A method for preparation of a surface plasmon resonance (SPR) sensor chip with 8-stripe pattern for multiplex immunoassay, where several kinds of antibodies can be immobilized, is proposed in this paper. For immobilization of two types of antibody, anti-IgA and anti-IgG antibodies on the sensor chip at 8-stripe pattern alternatively, a flow generated by the centrifugal force was used for introducing the antibody solutions separately into a microchip with 8-channel on the 8-stripe patterned sensor chip. The resulting sensor chip, on which the anti-IgA antibody and anti-IgG antibody were immobilized alternatively, was attached to a flow cell prepared from an acrylic with a single flow channel. Mixed solutions of IgA and IgG at different concentrations were injected into a carrier stream of a pH buffer solution at 7.4, and SPR sensor signals for IgA and IgG were detected separately from the SPR sensor chip with stripes immobilized with corresponding antibodies. As a result, calibration curves for IgA and IgG, which fit to those calculated from the Langmuir adsorption isotherm, were obtained. The detection limit of the SPR sensor was ca. 5 ppm.. |
| 14. |
Jie Zhan, Koji Furui, Hizuru Nakajima, Noriaki Kaneki, Ryoichi Ishimatsu, Koji Nakano, Toshihiko Imato, Development of a Portable Surface Plasmon Resonance Sensor with Multi-Sensing Points based on the Linear CCD Sensor, Analytical Sciences, DOI: 10.2116/analsci.32.673, 32, 6, 673-679, 2016.06. |
| 15. |
Ryoichi Ishimatsu, Tomohiko Ezura, Chihaya Aachi, Koji Nakano, Toshihiko Imato, Photophysical Properties and Efficient Stable Electrogenerated Chemiluminescence of Donor-Acceptor Molecules Exhibiting Thermal Spin Up-Conversion, Chemistry a European Journal, DOI:10.1002/chem.201600077, 22, 3, 4889-4898, 2016.03. |
| 16. |
Anastasiia PETROVA, Ryoichi Ishimatsu, Koji Nakano, Toshihiko Imato, Andrey VISHNIKIN, Leonid MOSKVIN, Andrey BULATOV, Flow-Injection Spectrophotometric Determination of Cysteine in Biologically Active Dietary Supplements, Journal of Analytical Chemistry, DOI: 10.1134/S1061934816020118, 71, 2, 172-178, 2016.02, A procedure is developed for the flow-injection spectrophotometric determination of cysteine in dietary supplements based on the formation of a reduced phosphomolybdic complex by the analyte in mixing a sample solution with a solution of ammonium 18-molybdophosphate. For the flow-injection determination of cysteine, a polymethyl methacrylate chip is fabricated, in the channels of which the analytical form was obtained and detected. The detection limit for cysteine is 3 × 10–6 M and the throughput is 240 determinations per hour. The procedure was tested in the analysis of different samples of dietary supplements; the results obtained were verified by HPLC.. |
| 17. |
Koji Nakano, Shingo Hirata, Jun Horiuchi, Ryoichi Ishimatsu, Toshihiko Imato, Takeshi Onodera, Kenshi Hayashi, Synthesis and Self-Assembly of His-tag Hybrid of Substrate-Binging Short Domain in Transient Receptor Potential Vanilloid Type 1 for Vanaillin Sensing Application, Transactions of the Materials Research Society of Japan, http://doi.org/10.14723/tmrsj.40.175, 40, 2, 175-178, 2015.07. |
| 18. |
Anastasiia PETROVA, Andrey BULATOV, Andrey VISHNIKIN, Leonid MOSKVIN, Ryoichi Ishimatsu, Koji Nakano, Toshihiko Imato, A Miniaturized Stepwise Injection Spectrophotometric Analyzer, Analytical Sciences, http://doi.org/10.2116/analsci.31.529, 31, 6, 529-533, 2015.06. |
| 19. |
Poomrat Rattanarat, Prinjaporn Teengam, Weena Siangproh, Ryoichi Ishimatsu, Koji Nakano, Orawon Chailapakul, Toshihiko Imato, An Electrochemical Compact Disk-type Microfluidics Platform for Use as an Enzymatic Biosensor, Electroanalysis, http://dx.doi.org/10.1002/elan.201400590, 27, 703-712, 2015.03. |
| 20. |
Rong Liu, Ryoichi Ishimatsu, Masayuki Yahiro, Chihaya Aachi, Koji Nakano, Toshihiko Imato, Fluorometric flow-immunoassay for alkylphenol polyethoxylates on a microchip containing a fluorescence detector comprised of an organic light emitting diode and an organic photodiode, Talanta, http://dx.doi.org/10.1016/j.talanta.2014.10.055, 134, 37-47, 2015.03. |
| 21. |
Sui Guo, Ryoichi Ishimatsu, Koji Nakano, Toshihiko Imato, Automated Chemiluminescence Immunoassay for a Nonionic Surfactant using a Recycled Spinning-pausing Controlled Washing Procedure on a Compact Disc-type Microfluidic Platform, Talanta, http://dx.doi.org/10.1016/j.talanta.2014.06.075, 133, 100-106, 2015.02. |
| 22. |
Rong Liu, Ryoichi Ishimatsu, Masayuki Yahiro, Chihaya Aachi, Koji Nakano, Toshihiko Imato, Photometric Flow Injection Determination of Phosphate on a PDMS Microchip Using an Optical Detection System Assembled with an Organic Light Emitting Diode and an Organic Photodiode, Talanta, http://dx.doi.org/10.1016/j.talanta.2014.08.057, 132, 96-105, 2015.01. |
| 23. |
Ryoichi Ishimatsu, Ruey-Feng Chang, Yuko Kirino, Koji Nakano, Toshihiko Imato, 表面プラズモン共鳴センサを利用した 免疫グロブリンGのフローインジェクション分析, J. Flow Injection Analysis, https://doi.org/10.24688/jfia.31.2_111, 31, 2, 111-114, 2014.12, Direct detection of immunoglobulin G (IgG) by using a surface plasmon resonance (SPR) sensor through an antigen‒antibody interaction was described. An anti‒IgG antibody was chemically immobilized on a sensor chip through a self‒assembled monolayer (SAM) in order to enhance the recognition of an IgG antigen. By assuming the Langmuir adsorption isotherm, maximum amount of adsorbed anti‒IgG antibody on the sensor chip and an apparent biding constant of the IgG antigen to anti‒IgG antibody were estimated. The amount of the IgG antigen bound to the anti‒IgG antibody, which was immobilized onto the sensor chip through the SAM was three times higher compared with the amount of the IgG antigen bound to the anti‒IgG antibody, which was immobilized directly to the sensor chip through physical adsorption.. |
| 24. |
Ryoichi Ishimatsu, Shigeyuki Matsunami, Takashi Kasahara, Ｊｕｎ Ｍｉｚｕｎｏ, Tomohiko Ezura, Chihaya Aachi, Koji Nakano, Toshihiko Imato, Electrogenerated Chemiluminescence of Donor-Acceptor Molecules Displaying Thermally Activated Delayed Fluorescence, Angewandte Chemie International Edition, http://dx.doi.org/10.1002/anie.201402615, 53, 6933-6996, 2014.07. |
| 25. |
Koji Nakano, Takayuki Kimura, Yosuke Kitamura, Toshihiro Ihara, Ryoichi Ishimatsu, Toshihiko Imato, Potentiometric DNA Sensing Platform Using Redox-active DNA Probe Pair for Sandwich-type Dual Hybridization at Indicator Electrode Surface, Journal of Electroanalytical Chemistry, http://dx.doi.org/10.1016/j.jelechem.2014.03.029, 720-721, 71-75, 2014.04, A potentiometric sensing platform that enables real-time DNA hybridization detection is described. A model target DNA, t37s: 5'AAA AAA AAA AAA-(TC)2-Ts5-(TC)2-GGA GCT GGT GGC3', which consist of a dodecamer polydeoxyadenylic acid and the human K-ras oncogene, and a five-successive deoxythymidine phosphorothioate (Ts) was designed. With the gold–phosphorothioate binding, the DNA could bind the complementarily sequences to concentrate them at the gold electrode surfaces. Accordingly, a dodecamer polydeoxythymidylic acid having ferroin-moiety (T12FeP) and a ferrocene-modified complementary of K-ras (KrasFc) were synthesized. Electrochemical quartz-crystal-microbalance (QCM) using Au-sputtered quartz chips that served as the indicator electrode collected the electrode responses. When the electrode surface was treated with the T12FeP-hybridizad t37s, which were subsequently oxidized to the corresponding Fe(III) form, the emf developed in a buffer solution responded to KrasFc; with the electrode-attached t37s the redox-active DNAs could group into a pair to establish specific redox-titration equilibrium. A QCM confirmed the on-electrode titrimetry feasible by determining the initial concentration and the amount of hybridization along with the emf measurements. Although the present method is necessary for two-kinds of redox conjugation of the target DNA, it should be important as a novel framework of electrochemical gene sensing. Preliminary examples of real-time measurement were also demonstrated with the results of kinetics analysis data.. |
| 26. |
Ryoichi Ishimatsu, Azusa Naruse, Rong Liu, Koji Nakano, Masayuki Yahiro, Chihaya Aachi, Toshihiko Imato, An Organic Thin Film Photodiode as a Portable Photodetector for the Detection of Alkylphenol Polyethoxylates by a Flow Fluorescence-Immunoassay on Magnetic Microbeads in a Microchannel, Talanta, http://dx.doi.org/10.1016/j.talanta.2013.08.044, 117, 139-145, 2013.12. |
| 27. |
Ryoichi Ishimatsu, Shigeyuki Matsunami, Katsuyuki Shizu, Chihaya Aachi, Koji Nakano, Toshihiko Imato, Solvent Effect on Thermally Activated Delayed Fluorescence by 1,2,3,5-Tetrakis(carbazol-9-yl)-4,6-dicyanobenzene, The Journal of Physical Chemistry A, http://dx.doi.org/10.1021/jp404120s, 117, 27, 5607-5612, 2013.06. |
| 28. |
Hisao Yoshinaga, Koji Nakano, Nobuaki Soh, Ishimatsu Ryoichi, Toshihiko Imato, A Pivot-Hinge-Style DNA Immobilization Method with Adaptable Surface Concentration Based on Oligodeoxynucleotide-Phosphorothioate Chemisorption on Gold Surfaces, Anal. Sci., https://doi.org/10.2116/analsci.28.1059, 28, 11, 1059-1064, 2012.11. |
| 29. |
Hisao Yoshinaga, Koji Nakano, Nobuaki Soh, Toshihiko Imato, AFM-Imaging Diagonosis Method for Single Nucleotide Polymorphism Using Molecular Beacon DNA as an Intramolecullar Ligation Template of Target DNA and a Viewable Indicator, Anal. Sci., https://doi.org/10.2116/analsci.28.939, 28, 10, 939-945, 2012.10. |
| 30. |
北岡 桃子, Masayuki Mitsumori, Kounosuke Hayashi, Yoshiyuki Hiraishi, Hisao Yoshinaga, Koji Nakano, Katsuyuki Miyawaki, Sumihare Noji, Masahiro Goto, Noriho Kamiya, Transglutaminase-Mediated in Situ Hybridization (TransISH) System: A New Methodology for Simplified mRNA Detection, Anal. Chem., https://doi.org/10.1021/ac2034198, 84, 14, 5885-5891, 2012.07. |
| 31. |
Josui Shimada, Tatsuo Maruyama, 北岡 桃子, Hisao Yoshinaga, Koji Nakano, Noriho Kamiya, Masahiro Goto, Programmable protein–protein conjugation via DNA-based self-assembly, Chem. Commun., https://doi.org/10.1039/C2CC30618B, 48, 50, 6226-6228, 2012.06. |
| 32. |
D. Seto, T. Maki, Nobuaki Soh, Koji Nakano, Ishimatsu Ryoichi, Toshihiko Imato, A Simple and Selective Fluorometric Assay for Dopamine using a Calcein Blue-Fe2+ Complex Fluorophore, Talanta, doi:10.1016/j.talanta.2012.02.025, 94, 36-43, 2012.05, A surface plasmon resonance (SPR) sensor on a compact disk (CD)-type microfluidic device was developed to miniaturize the elements of a complete analytical system, pump and valves. The CD-type microfluidic device was fabricated by attaching a poly- dimethylsiloxane disk plate that contained microchannels and reservoirs to a flat poly- carbonate disk plate that contained grating films with a thin layer of Au. The optical system of the SPR sensor and the theory for its operation are based on the principle of a grating coupled-type SPR. The sample and reagent solutions in the reservoirs on the CD- type microfluidic device were sequentially introduced into the detection chamber by centrifugal force generated by the rotation of the microfluidic device. The variation of resonance wavelength was dependent on the refractive index of the sample solution. This CD-type SPR sensor was successfully used in an immunoassay of immunoglobulin A (IgA). The anti-IgA, blocking reagent, sample and washing solution in the reservoirs were sequentially introduced into the detection chamber by changing the frequency of rotation of the microfluidic device. IgA in the sample solution was adsorbed to the anti-IgA immobilized on the Au thin layer in the detection chamber and was then detected by the SPR sensor.. |
| 33. |
M. Miyake, Hizuru Nakajima, A. Henmi, M. Yahiro, CHIHAYA ADACHI, Nobuaki Soh, Ishimatsu Ryoichi, Koji Nakano, K. Uchiyama, Toshihiko Imato, Performance of an organic photodiode as an optical detector and its application to fluorometric flow-immunoassay for IgA, Talanta, doi:10.1016/j.talanta.2012.02.006, 96, 132-139, 2012.07, The performance of an organic thin film photodiode (OPD), fabricated from a hetero-junction comprised of two layers of C60 and a phthalocyanine-Cu(II) complex was evaluated by detecting the chemilumi- nescence generated from the reaction of luminol with horseradish peroxidase in the presence of H2O2, and the fluorescence from resorufin, as an optical detector. The photocurrent of the OPD was linear with respect to the power of light from a commercial LED. The sensitivity of the OPD was sufficient for detecting chemiluminescence with a power 0.1 W/cm2 . The OPD was successfully used in a flow-immunoassay for IgA, a marker of human stress, in which a sandwich immunoassay was carried out on the microchip and the fluorescence from resorufin, produced by the enzymatic reaction, was detected. The detection limits for resorufin and IgA were 5.0 M and 16 ng/mL, respectively. The photosensitivity of the OPD remained relatively constant for a minimum of one year.. |
| 34. |
Shuai Guo, Koji Nakano, Hizuru Nakajima, Katsumi Uchiyama, Akihide Hammi, Yoshikazu Yamasaki, Shigeharu Morooka, Ishimatsu Ryoichi, Toshihiko Imato, Chemiluminescence immunoassay for a nonionic surfactant using a compact disc-type microfluidic platform, Pure and Applied Chemistry, https://doi.org/10.1351/PAC-CON-11-10-10, 84, 10, 2027-2043, 2012.10, A simple and pump-free chemiluminescence immunoassay based on a compactdisc (CD)-type microfluidic platform for the determination of alkylphenol polyethoxylates(APnEOs) is described. The method is based on a competitive immunoreaction of the anti-APnEOs antibody immobilized on the magnetic microbeads between APnEOs and horse-radish peroxidase (HRP)-labeled APnEOs in the sample solution. The luminol solutioncontaining H2O2and enhancer is caused to flow from one reservoir in the platform to anotherby appropriate adjustment of the speed of the rotation of the disc. The detection limit wassimilar to that reported in our previous paper, i.e., 10 ppb according to IC80.. |
| 35. |
Akihide Hemmi, Takashi Usui. Akihiro Moto, Tatsuya Tobita, Nobuaki Soh, Koji Nakano, Hulie Zeng, Katsumi Uchiyama, Toshihiko Imato, Hizuru Nakajima, A surface plasmon resonance sensor on a compact disk-type microfluidic device, J. Separation Science, https://doi.org/10.1002/jssc.201100446, 34, 20, 2913-2919, 2011.10. |
| 36. |
HIZURU Nakajima, Yukiko Okuma, Kazuhiro Morioka, Mayo Miyake, Akihide Hemmi, Tatsuya Tobita, Masayuki Yahiro, Daisuke Yokoyama, Chihaya Adachi, Nobuaki Soh, Koji Nakano, Shuhua Xue, Hulie Zeng, Katsumi Uchiyama, Toshihiko Imato, An integrated enzyme-linked immunosorbent assay system with an organic light-emitting diode and a chargecoupled device for fluorescence detection, J. Separation Science, DOI 10.1002/jssc.201100429, 34, 20, 2906-2912, 2011.10, A fluorescence detection system for a microfluidic device using an organic light-emitting diode (OLED) as the excitation light source and a charge-coupled device (CCD) as the photo detector was developed. The OLED was fabricated on a glass plate by photo- lithography and a vacuum deposition technique. The OLED produced a green lumines- cence with a peak emission at 512 nm and a half bandwidth of 55 nm. The maximum external quantum efficiency of the OLED was 7.2%. The emission intensity of the OLED at 10 mA/cm2 was 13 mW (1.7 mW/cm2). The fluorescence detection system consisted of the OLED device, two band-pass filters, a five microchannel poly(dimethylsiloxane) (PDMS) microfluidic device and a linear CCD. The fluorescence detection system was successfully used in a flow-based enzyme-linked immunosorbent assay on a PDMS microfluidic device for the rapid determination of immunoglobulin A (IgA), a marker for human stress. The detection limit (S/N 5 3) for IgA was 16.5 ng/mL, and the sensitivity was sufficient for evaluating stress. Compared with the conventional 96-well microtiter plate assay, the analysis time and the amounts of reagent and sample solutions could all be reduced.. |
| 37. |
TOMOHARU MAKI, NOBUAKI SOH, Koji NAKANO, TOSHIHIKO IMATO, Flow injection fluorometric determination of ascorbic acid using perylenebisimide-linked nitroxide, Talanta, doi:10.1016/j.talanta.2011.06.054, 85, 4, 1730-1733, 2011.09, A simple and sensitive flow injection fluorometric method for the determination of ascorbic acid is described. Perylenebisimide-linked nitroxide (PBILN) is used as a fluorescent reagent, which permits the selective determination of ascorbic acid. The fluorescence of the perylenebisimide moiety in PBILN is quenched by the nitroxide moiety, which is linked to the perylenebisimide. When a stream of a solution of ascorbic acid is merged with a stream of PBILN, the ascorbic acid reacts with the nitroxide moiety of PBILN to form hydroxylamine, and the fluorescence properties of the perylenebisimide moiety are recovered. As a result, a peak-shaped fluorescence signal is produced, which can be observed by a fluo- rescence detector located downstream. Under optimized conditions, a good linear relationship between the concentration of ascorbic acid and peak height in the concentration range from 0.5 to 10 mol L−1 was found and the detection limit (S/N = 3) was 0.28 mol L−1 . The relative standard deviation for the determination of 4.0 mol L−1 ascorbic acid samples was 1.0% (n = 5). The proposed method was applied to the determination of ascorbic acid in several soft drink beverages and the analytical results were in good agreement with those obtained using a conventional method.. |
| 38. |
V. GUZSVANY, H. NAKAJIMA, N. SOH, K. NAKANO, I. SVANCARA, K. VYTRAS, L. BJELICA, T. IMATO, Anodic Stripping Voltammetry Combined with Sequential Injection Analysis for Measurements of Trace Metal Ions with Bismuth- and Antimony Film Electrodes under Comparable Conditions, Electroanalysis, https://doi.org/10.1002/elan.201000683, 23, 7, 1539-1601, 2011.07, Anodic stripping voltammetry combined with sequential injection analysis (ASV-SIA) was selected to examine the use of bismuth- and antimony-film plated glassy carbon electrodes under comparable conditions for the determination of Pb(II) and Cd(II) ions. Of interest were the conditions for film deposition, as well as the composition of sample/carrier solutions, including concentrations of Sb(III) or Bi(III) and HCl. Then, by the optimized procedure, one could determine Pb(II), Cd(II), and Zn(II) ions at the low µg L−1 level and ASV-SIA configuration with both electrodes tested on analysis of a water sample.. |
| 39. |
T. YAMASAKI, F. MITO, Y. ITO, S. PANDIAN, Y. KINOSHITA, K. NAKANO, R. MURUGESAN, K. SAKAI, H. UTSUMI, K. YAMASHITA, Structure-Reactivity Relationship of Piperidine Nitroxide: Electrochemical, ESR and Computational Studies, J. Organic Chemistry, DOI: 10.1021/jo101961m, 76, 2, 435-440, 2011.01, We have synthesized several nitroxides with different substituents which vary the steric and electronic environment around the N-O moiety and have systematically investigated the role of substituents on the stability of the radicals. Our results demonstrated the reactivity toward ascorbate correlates with the redox potential of the derivatives. Furthermore, ab initio calculations also indicated a correlation between the reduction rate and the computed singly occupied molecular orbital-lowest unoccupied molecular orbital energy gap, but not with solvent accessible surface area of the N-O moiety, supporting the experimental results and suggesting that the electronic factors largely determine the radicals’ stability. Hence, it is possible to perform virtual screening of nitroxides to optimize their stability, which can help to rationally design novel nitroxides for their potential use in vivo.. |
| 40. |
Daisuke Seto, Nobuaki Soh, Koji Nakano, Toshihiko Imato, An Amphiphilic Fluorescent Probe for the Visualization of Histamine in Living Cells, Bioorg. Med. Chem. Lett., doi:10.1016/j.bmcl.2010.09.003, 20, 6708-6711, 2010.11, A novel fluorescent probe composed of two moieties, Nile Red and an iminodiacetic acid–Ni2+ complex,
for the detection of histamine in living cells is described. The probe was successfully applied to visualizing histamine in RAW264 cells, representing the first demonstration of the imaging of histamine itself in
living cells.. |
| 41. |
Daisuke Seto, Nobuaki Soh, Koji Nakano, Toshihiko Imato, Selective Fluorescence Detection of Histamine Based on Ligand Exchange Mechanism and Its Application to Biomonitoring, Anal. Biochem., https://doi.org/10.1016/j.ab.2010.04.038, 404, 2, 135-139, 2010.09, We report on a novel histamine monitoring method by using a fluorescent probe, a complex between Ni2+ and calcein, based on a ligand exchange mechanism. The fluorescence intensity of this probe, which has been reduced due to effective quenching by Ni2+ ion, increases drastically by an addition of histamine. Furthermore, the probe shows high selectivity toward histamine among the various neurotransmitters in 0.1 M phosphate buffer solution (pH 7.4). Biomonitoring studies to detect histamine released from RAW264 cells are successfully represented.. |
| 42. |
Koji Nakano, Hirokazu Yamanouchi, Hisao Yoshinaga, Nobuaki Soh, Toshihiko Imato, Label-free DNA Detection Platform Based on Atomic Force Microscopy Visualisation: Characterising the Molecular-Recognition-Triggered Conformational Changes of an Immobilised Receptor Oligonucleotide Probe, Chem. Commun., https://doi.org/10.1039/C002642E, 46, 13, 5683-5685, 2010.06, Using atomic microscopy imaging, probe DNA sequence self-assemblies developed on Si(100) substrates undergo a conformational transition from an extended stem-loop structure to a double helix; such assemblies readily report on DNA molecular recognition events and should be suitable as a label-free, DNA hybridisation assay platform.. |
| 43. |
Koji Nakano, Yosuke Katsumi, Nobuaki Soh, Toshihiko Imato, An Atomic Force Microscopy Assay of Intercalation Binding, Unwinding and Elongation of DNA, Using a Water-Soluble Psoralen Derivative as a Covalent Binding Probe Molecule, Bull. Chem. Soc. Jpn, https://doi.org/10.1246/bcsj.20090166, 2010, 3, 273-275, 2010.03, A single-molecule strategy using atomic force microscopy has simply yet robustly probed an intercalation binding
related specific structural relaxation of covalently closed
circular pBR322 DNA as well as double-strand elongation in
its linear form by taking advantage of a new psoralen
derivative, N,N,N-trimethyl-1-(2,5,9-trimethyl-7-oxo-7Hfuro[3,2-g]chromen-3-yl)methanaminium chloride, that covalently binds to DNA through a photo-crosslinking reaction.. |
| 44. |
Valéria GUZSVANY, Hizuru NAKAJIMA, Nobuaki SOH, Koji NAKANO, Toshihiko IMATO, Antimony-Film Electrode for the Determination of Trace Metals by Sequential-Injection Analysis/Anodic Stripping Voltammetry, Anal. Chim. Acta, https://doi.org/10.1016/j.aca.2009.10.049, 658, 12-17, 12-17, 2010.01, The possibility of applying antimony-film modified glassy carbon electrode in sequential-injection analysis (SIA) was investigated with the objective of determining Pb(II) and Cd(II) by anodic stripping voltammetry (ASV). The conditions of antimony-film deposition concerning composition of the plating/carrier solutions, concentrations of Sb(III) and hydrochloric acid, effects of different supporting electrolyte salts, and plating potential were optimized. It was found that the antimony-film deposition on glassy carbon substrate in a sample solution consisting of 750 μg L−1 Sb(III), 0.5 mol L−1 HCl at −1.5 V (vs. Ag/AgCl/3 mol L−1 KCl) yielded a modified electrode suitable for the determination of Pb(II) and Cd(II) at the μg L−1 level. The reproducibility of the analytical signals was characterized by a relative standard deviation lower than 2.8%, and the calculated values of detection limits were 1.2 μg L−1 for Pb(II) and 1.4 μg L−1 for Cd(II). The presence of KSCN in the sample solution offers the possibility of detecting ions with more negative oxidation potentials like Zn(II), Mn(II) or Cr(III). The developed SIA-ASV procedure was compared with the commonly used batch method, and its applicability was tested on a spiked tap water sample.. |
| 45. |
Noriho Kamiya, Yoshiaki Shiotari, Masamichi Tokunaga, Hideshi Matsunaga, Hirokazu Yamanouchi, Koji Nakano, Masahiro Goto, Stimuli-responsive nanoparticles composed of naturally occurring amphiphilic proteins, Chem. Commun., DOI https://doi.org/10.1039/B909897F, 2009, 35, 5287-5289, 2010.09, Simple chemical cross-linking of β-casein micelles resulted in the formation of thermally responsive proteinaceous nanoparticles that exhibit lower critical solution temperatures.. |
| 46. |
Mayumi TANAKA, Kazuhira SAKAMOTO, Hizuru NAKAJIMA, Nobuaki SOH, Koji NAKANO, Takashi MASADOME, Toshihiko IMATO, Flow Immunoassay for Nonioinic Surfactants Based on Surface Plasmon Resonance Sensors, Anal.Sci., https://doi.org/10.2116/analsci.25.999, 25, 8, 999-1005, 2009.08, A rapid, sensitive immunoassay based on a surface plasmon resonance sensor in a flow system for the determination of alkylphenol polyethoxylate (APEO) is described. The method is based on an indirect competitive reaction between an anti-APEO antibody in the sample solution and APEO immobilized on a sensor chip and APEO in the same sample solution. A sensor chip was prepared by immobilizing an APEO-horseradish peroxidase (APEO-HRP) conjugate on the thin gold film of the sensor chip. The adsorption constants for the APEO-HRP conjugate on the sensor chip and the surface density of the APEO-HRP adsorbed on the sensor chip at the saturated state were estimated to be 4.7 × 105 M−1 and 5.0 × 10−14 mol/mm2, respectively, using a Langmuir adsorption isotherm equation and results from the adsorption experiments. The affinity constants for the immunocomplexes of the anti-APEO antibody with the APEO conjugate on the sensor chip and for APEO in the sample solution were estimated to 2.0 × 106 and 5.1 × 106 M−1, respectively. A typical sigmoid calibration curve for APEO was obtained in the concentration range from 1 ppb to 1000 ppb. The detection limit, defined as the concentration of APEO, at which 85% of the sensor signal was observed, was ca. 10 ppb. The assay was applied to the determination of APEO in tap water in conjunction with a solid phase extraction pretreatment; APEO levels of approximately 50 ppt were successfully determined.. |
| 47. |
Koji NAKANO, Hideshi MATSUNAGA, Masaharu MURATA, Nobuaki SOH, Toshihiko IMATO, Synthesis Of Circular Double-Stranded DNA Having Single-Stranded Recognition Sequence As Molecular-Physical Probe For Nucleic Acid Hybridization Detection Based On Atomic Force Microscopy Imaging, Anal. Sci., DOI: 10.2116/analsci.25.993, 25, 8, 993-998, 2009.08, A new class of DNA probes having a mechanically detectable tag is reported. The DNA probe, which consists of a
single-stranded recognition sequence and a double-stranded circular DNA entity, was prepared by polymerase reaction.
M13mp18 single strand and a 32mer oligodeoxynucleotide whose 5`-end is decorated with the recognition sequence were
used in combination as template and primer, respectively. We have successfully demonstrated that the DNA probe is
useful for bioanalytical purposes: by deliberately attaching target DNA molecules onto Au(111) substrates and by
mechanically reading out the tag-entity using a high-resolution microscopy including atomic force microscopy,
visualization/detection of the individual target/probe DNA conjugate was possible simply yet straightforwardly. The
present DNA probe can be characterized as a 100%-nucleic acid product material. It is simply available by one-pod
synthesis. A surface topology parameter, image roughness, has witnessed its importance as a quantitative analysis index
with particular usability in the present visualization/detection method.. |
| 48. |
Tomoharu Maki, Tuyoshi Fukaminato, Hizuru Nakajima, Koji Nakano, Toshihiko Imato, Perylenebisimide-linked nitroxide for the detection of hydroxyl radicals, Anal. Chim. Acta, https://doi.org/10.1016/j.aca.2009.02.044, 639, 1-2, 78-82, Vol. 639, No. 1, pp. 78–82, 2009.04, A new type of fluorophore-linked nitroxide for the detection of hydroxyl radical (radical dotOH) was synthesized using perylene-3,4,9,10-tetracarboxyl bisimide and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). This new fluorescent probe, indicated here as Spy-OH (swallow-tailed perylene derivative for detecting radical dotOH) has its natural fluorescence effectively reduced due to the quenching caused by the presence of the nitroxide radical in its structure. In the presence of radical dotOH, in media containing DMSO, a conspicuous increase in the fluorescence intensity was observed. No significant change in the fluorescence intensity was observed upon the addition of other several reactive oxygen species (ROS) except for radical dotOH. Spy-OH maxima excitation (λexc) and emission (λem) wavelengths lie in the visible region (520/530 nm), therefore, this fluorescent probe is expected to be useful for a simple and selective detection of radical dotOH, especially for biosamples.. |
| 49. |
K. Nakano, K. Nakamura, K. Iwamoto, N. Soh, T. Imato, Positive-feedback-mode scanning electrochemical microscopy imaging of redox-active DNA-poly(1,4-benzoquinone) conjugate deposited on carbon electrode for micrometer-sized hybridization biosensor applications, J. Electroanal. Chem., https://doi.org/10.1016/j.jelechem.2009.01.014, 628, 1-2, 113-118, Vol. 628, No. 1, pp. 113–118, 2009.02, Scanning electrochemical microscopy of DNA microdots deposited on carbon fiber microelectrodes (diameter, 33 μm) has been demonstrated. The microdots, which comprised quinone polymer matrices with capture probe (CP) DNA grafted onto them, can report hybridization events via changes in their electrochemical reactivity. Furthermore, the polymer matrices, even after conjugation with CP DNA, possess a certain degree of charge-transport capability and thus allow for positive-feedback-mode imaging. We have successfully obtained well-resolved micrometer-sized dot images (diameter, 60–100 μm) of the microelectrodes: they generate a considerable magnitude of current rise over 10 nA while they gave a current decrease, typically 1 nA, in responding the hybridization event at the CP DNA. The sensor response was found to fall a little larger than the background current (0.6–0.8 nA). However, the particular SECM measurement system represented good signal-to-noise ratio reliably allowing the detection of DNA hybridization feasible. Obtaining these results, we have concluded that the particular DNA-modified electrode with SECM detection should be useful for readout of DNA hybridization sensor coupled with a high-throughput-device such as DNA microarrays.. |
| 50. |
M. Tanaka, Y. Li, H. Nakajima, N. Soh, K. Nakano, K. Sakamot, T. Imato, Sequential Injection Flow Immunoassay Based on Surface Plasmon Resonance Sensors, J. Flow Injection Analysis, https://doi.org/10.24688/jfia.25.2_172, 25, 2, 172-182, \Vol. 25, No. 2, 172–182, 2008.12, Flow immunoassay methods for the determination of several environmental pollutants, such as 2,4-dichlorophenol, bisphenol A, trinitrophenol, pesticides and allergy related compounds, such as histamine and immunoglobulin E (IgE) based on a surface plasmon resonance (SPR) sensor are reviewed from the view point of methodology of immunoassay. In this review, two types of immobilization methods for an antibody or an antigen conjugate for the target molecule on the sensor chip are proposed. One is the immobilization method for the antibody of the target molecule, where the antibody is immobilized on the sensor chip through a gold binding polypeptide and Protein G by taking into account of high orientation of the antibody for an immunoreaction on the sensor chip. The other method is the immobilization of the antigen conjugate in two way, where an antigen conjugate with protein such as bovine serum albumin is immobilized by physical adsorption and an antigen conjugate is immobilized by amino-coupling with an alkane thiol compound, which is preliminary immobilized on the sensor chip as a self-assembled monolayer. In order to enhance the sensitivity of the SPR sensor by increasing the change in the mass on the sensor chip after the immunoreaction, a competitive immunoreactions is adopted for the both immobilization methods, where the antibody or the antigen conjugate is immobilized on the sensor chip. A sandwich immunoassay method for the allergy related compound, IgE, was demonstrated as a sensitive method for enhancement of the SPR sensor signal. In the present flow immunoassay, a sequential injection technique is utilized in order to automate the immunoassay protocol, which consists of many procedures.. |
| 51. |
Y. Li, J. Ren, H. Nakajima, B.-K. Kim, N. Soh, K. Nakano, T. Imato, Flow sandwich immunoassay for specific anti-OVA IgG antibody by use of surface plasmon resonance sensor, Talanta, https://doi.org/10.1016/j.talanta.2008.03.007, 77, 2, 423-478, Vol. 77, No. 2, pp. 423–478, 2008.12, A simple and sensitive method for the determination of a specific IgG antibody against ovalbumin (anti-OVA IgG antibody) for diagnosis of egg allergy by use of a surface plasmon resonance (SPR) immunosensor in a flow system is described. An OVA conjugate was immobilized on a sensor chip via a self-assembled monolayer of 11-mercaptoundecanoic acid through an amino coupling method. The determination of the anti-OVA IgG antibody was based on a kind of sandwich immunoassay using an anti-IgG secondary antibody in order to enhance the sensitivity of the SPR immunosensor. The sensitivity and detection limit of the present method for the anti-OVA IgG antibody were 7 mdeg/ppm and 300 ppb, respectively. The present method showed an enhanced sensitivity and detection limit for the determination of the anti-OVA antibody, compared with a direct immunoassay, by which the sensitivity and detection limit were 3 mdeg/ppm and 1 ppm, respectively. By assuming a Langmuir type of adsorption isotherm, the affinity constants of an anti-OVA IgG antibody immunocomplex with the anti-IgG secondary antibody and of the anti-OVA antibody to the OVA conjugate immobilized on the sensor chip were calculated to be 2.1 × 106 M−1 and 2.0 × 106 M−1, respectively. The present flow immunoassay for the anti-OVA IgG antibody by an SPR sensor has potential applications in both research and diagnosis of egg allergy.. |
| 52. |
K. Nakano, K. Ohkubo, H. Taira, M. Takagi, N. Soh, T. Imato, Synthesis of 1,4-hydroquinone-terminated alkanethiol and self-assembly on gold as characterized by interfacial electrochemistry, electrocatalysis application and ab initio calculation based on comparison with catechol-presenting analogue., J. Electroanal. Chem., https://doi.org/10.1016/j.jelechem.2008.06.016, 623, 1, 49-53, Vol. 623, No. 1, pp. 49-53, 2008.11, Synthesis and self-assembly of a mercaptoundecaneamide derivative having a terminus of 1,4-hydroquinone (QT) are described. Electrochemical measurements on the QT-modified Au electrode revealed that the alkanethiol compound undergoes self-assembly to exhibit specific electrochemical activity originates from the reversible quinone/hydroquinone redox reaction at the terminus. We have achieved to obtain the electrochemical active surface coverage (0.11 nmol cm−2), formal potential (+246 mV, pH 3, Ag/AgCl) that changes pH-dependently (58 mV per pH) and also a set of the electron transfer reaction parameters, all of which were consistent with those of the previously reported structural isomer, catechol-terminated mercaptoundecaneamide (CT). Contrastingly, we found that these alkanethiol monolayers give marked contrast in an elecrocatalysis application: the CT-monolayer electrodes showed electrocatalytic capability in oxidation of NADH solution species while the QT-monolayer electrodes did not at all. By comparing some results of theoretical approach, we have attributed the surface selectivity to the spatiality of particular molecular orbital in the catalysis molecule. This observation should be important as an example of spatiality–reactivity relationships in a molecular design of chemically modified electrode.. |
| 53. |
K. Nakano, K. Ohkubo, H. Taira, M. Takagi, T. Imato, Electrocatalytic oxidation of dihydronicotineamide adenine dinucleotide on gold electrode modified with catechol-terminated alkanethiol self-assembly, Anal. Chim. Acta, https://doi.org/10.1016/j.aca.2008.02.009, 619, 1, 30-36, Vol. 619, No. 1, pp. 30–36, 2008.06, Synthesis of a mercaptoundecaneamide derivative having a terminus of catechol is described. FT-IR spectroscopic characterization showed that the new molecular entry simply undergoes molecular self-assembly on Au substrate surfaces promoting intra- and intermolecular hydrogen bonds to form well-packed monolayers. Cyclic voltammetric (CV) measurements on the monolayer-modified Au electrode revealed that the surface adlayer possesses specific electrochemical activity due to the reversible catechol/o-quinone redox reaction having characteristics of a surface process and also pH-dependence in its formal potential (59 mV per pH). Detailed analysis of CVs gave fundamental electrochemical parameters including the electroactive surface coverage (0.20–0.24 nmol cm−2), the transfer coefficients (0.24 in oxidation and 0.81 in reduction), and also the electron transfer rate constant (1.10–2.76 s−1). These data were almost consistent to those seen in literature. We have also found that the catechol monolayer modified electrode exhibits an electrocatalytic function in NADH oxidation. That is, the faradaic current appeared reinforcingly at around the same potential where catechol function is oxidized in the monolayer and increased with an increase in the NADH concentration from 1 to 5 mM, and then reached to a plateau indicating a catalyzed reaction pathway. Detailed analyses revealed that the present system could be characterized by its weak stability of the intermediate compound formed and prompt reaction rate compared with the previously reported chemically modified electrode (CME) systems. We think this type of achievement should be important for the basics of biosensors that rely on dehydrogenase enzymes.. |
| 54. |
N. Soh, K. Makihara, T. Ariyoshi, D. Seto, T. Maki, H. Nakajima, K. Nakano, T. Imato, Phospholipid-linked Coumarin: A Fluorescent Probe for Sensing Hydroxyl Radicals in Lipid Membrane, Analytica Sciences, https://doi.org/10.2116/analsci.24.293, 24, 2, 293-296, Vol. 24, No. 2, pp. 293–296, 2008.02, A fluorescent probe, DPPEC (1,2-dipalmitoylglycerophosphorylethanolamine labeled with coumarin) was developed for detecting hydroxyl radical (·OH) in lipid membranes. The coumarin moiety contributes to the fluorescent detection of ·OH and the phospholipids moiety gives a driving force to localize the probe in lipid membranes. DPPEC in liposomal membranes rapidly reacted with ·OH and increased the fluorescence intensity, depending on the concentration of ·OH. The increase in the fluorescence intensity induced by ·OH was effectively suppressed by the addition of DMSO. The probe exhibited a higher fluorescence response to ·OH over other reactive oxygen species, such as hydrogen peroxide, nitric oxide, peroxynitrite, alkylperoxyl radical, and hypochlorite. DPPEC would be useful as a new type of fluorescent probe that can localize in lipid membranes and detect ·OH efficiently.. |
| 55. |
N. Soh, K. Yoshida, H. Nakajima, K. Nakano, T. Imato, T. Fukaminato, M. Irie, A fluorescent photochromic compound for labeling biomolecules, Chemical Communications, DOI https://doi.org/10.1039/B713663C, 2007, 28, 5206-5208, Vol. 2007, No. 28, pp. 5206–5208, 2007.12, A fluorescent photochromic compound, composed of diarylethene, fluorescein and succinimidyl ester units, was developed for the controllable fluorescent labeling of biomolecules based on a small molecule.. |
| 56. |
N. Soh, T. Ariyoshi, T. Fukaminato, H. Nakajima, K. Nakano, T. Imato, Swallow-tailed perylene derivative: a new tool for fluorescent imaging of lipid hydroperoxides, Organic Bimolecular Chemistry, https://doi.org/10.1039/B713223A, 5, 23, 3762-3768, Vol. 5, No. 23, pp. 3762–3768, 2007.12, A swallow-tailed perylene derivative including a triphenylphosphine moiety was synthesized and applied to the detection and the live-cell imaging of lipid hydroperoxides. The novel probe, named Spy-LHP, reacted rapidly and quantitatively with lipid hydroperoxides to form the corresponding oxide, Spy-LHPOx, which emits extremely strong fluorescence (Φ ∼ 1) in the visible range (λem = 535 nm, 574 nm). Spy-LHP was highly selective for lipid hydroperoxides, and the addition of other reactive oxygen species (ROS) including hydrogen peroxides, hydroxyl radical, superoxide anion, nitric oxide, peroxynitrite, and alkylperoxyl radical, caused no significant increase in the fluorescence intensity. The probe exhibited good localization to cellular membranes and was successfully applied to the confocal laser scanning microscopy (CLSM) imaging of lipid hydroperoxides in live J774A.1 cells, in which lipid peroxidation was proceeded by the stimulation of 2,2-azobis(2-amidinopropane)dihydrochloride (AAPH). These findings establish Spy-LHP as a promising new tool for investigating the physiology of lipid hydroperoxides.
. |
| 57. |
RuiQi Zhang, Hizuru Nakajima, Nobuaki Soh, Koji Nakano, Takashi Masadome, Kazumi Nagata, Kazuhira Sakamoto, Toshihiko Imato, Sequential Injection Chemiluminescence Immunoassay for Nonionic Surfactants Using Magnetic Microbeads, Analytica Chimica Acta, DOI: 10.1016/j.aca.2007.02.052, 600, 1-2, 105-113, Vol. 600, No. 1, pp. 105–113, 2007.09, A rapid and sensitive immunoassay based on a sequential injection analysis (SIA) using magnetic microbeads for the determination of alkylphenol polyethoxylates (APnEOs) is described. An SIA system was constructed from a syringe pump, a switching valve, a flow-through type immunoreaction cell equipped with a photon counting unit and a neodymium magnet. Magnetic beads, to which an anti-APnEOs monoclonal antibody was immobilized, were used as a solid support in an immunoassay. The introduction, trapping and release of the magnetic beads in and from the immunoreaction cell were controlled by means of a neodymium magnet and adjusting the flow of a carrier solution. The immunoassay was based on an indirect competitive immunoreaction of an anti-APnEOs monoclonal antibody immobilized on the magnetic beads with a sample APnEOs and a horseradish peroxidase (HRP)-labeled APnEOs in the same sample solution, and was based on the subsequent chemiluminscence reaction of HRP on the magnetic microbeads with a luminol solution containing hydrogen peroxide and p-iodophenol. The anti-APnEOs antibody was immobilized on the magnetic microbeads by coupling the antibody with the magnetic beads after activation of a carboxylate moiety on the surface of the magnetic beads that had been coated with a polylactic acid film. The antibody immobilized magnetic beads were introduced in the immunoreaction cell and trapped in it by the neodymium magnet, which was equipped beneath the immunoreaction cell. An APnEOs sample solution containing the HRP-labeled APnEOs at a constant concentration, and a luminol solution containing hydrogen peroxide and p-iodophenol were sequentially introduced into the immunoreaction cell, according to an SIA programmed sequence. Chemiluminescence emission was monitored by means of a photon counting unit located at the upper side of the immunoreaction cell by collecting the emitted light with a lens. A typical sigmoidal calibration curve was obtained, when the logarithm of the concentration of APnEOs was plotted against the chemiluminescence intensity as the number of photons in 100 ms using standard APnEOs sample solutions at various concentrations (0-1000 ppb) under optimum conditions. The lower detection limit defined as IC(80) is ca 10 ppb. The time required for analysis is less than 15 min per a sample. The present method was successfully applied to the determination of APnEOs in river water.. |
| 58. |
Koji Nakano, Tadateru Yoshitake, Yasunori Yamashita, Edmond F. Bowden, Cytochrome c Self-Assembly on Alkanethiol Monolayer Electrodes as Characterized by AFM, IR, QCM, and Direct Electrochemistry, Langmuir, https://doi.org/10.1021/la063697w, 23, 11, 6270-6275, 2007.05, With the advantage of carbodiimide coupling chemistry, horse heart cytochrome c (cyt c) has been covalently immobilized onto self-assembled monolayers (SAMs) from 11-mercaptoundecanoic acid (MUDA) developed on single-crystal or polycrystalline gold substrate surfaces. The cyt c immobilized substrates thus prepared have been characterized by atomic force microscopy (AFM); we have succeeded in obtaining surface topographical images down to single-protein resolution. AFM imaging has also shown densely packed, uniform protein monolayer formation that is highly suggestive of self-assembly of cyt c molecules on MUDA SAMs. Covalent attachment of cyt c has been further evidenced by reflection−absorption FT-IR as well as microgravimetric analysis using a quartz crystal microbalance (QCM). In the latter, the specific MUDA and cyt c surface concentrations were determined to be 0.86 ± 0.11 nmol cm-2 (n = 5) and 28 ± 12 pmol cm-2 (n = 5), both of which agree fairly well with their theoretical counterparts. The obtained QCM chips having the cyt c/MUDA/Au interfacial structure were found to be capable of the direct electrochemistry of the surface-attached cyt c molecules. Cyclic voltammetric measurements on the chips gave particular redox waves showing characteristics of surface process. The electroactive protein surface concentration was determined to be 7.2 ± 4.8 pmol cm-2 (n = 6); it was almost consistent with values found in literature, while it was limited to 26% in magnitude for the QCM data. This was deemed to have arisen from the orientation variation of the surface-confined cyt c molecules and is discussed briefly.. |
| 59. |
Yan LI, Jujie REN, Hizuru NAKAJIMA, Nobuaki SOH, Koji NAKANO, Toshihiko IMATO, Surface Plasmon Resonance Immunosensor for IgE Analysis Using Two Types of Anti-IgE Antibodies with Different Active Recognition Sites, Analytical Sciences, https://doi.org/10.2116/analsci.23.31, 23, 1, 31-38, Vol. 23, No. 1, pp. 31 ? 38., 2007.01, A simple and novel method for the determination of an IgE antibody based on a surface plasmon resonance immunosensor for the diagnosis of an allergy is described. The method involves the use of an anti-IgE(D) antibody and an anti-IgE(H) antibody, which reacts with the Ce2 domain and the Ce3 domain of the IgE antibody. The anti-IgE(D) antibody was immobilized on the gold surface of a sensor chip by physical adsorption. An IgE antibody sample was incubated by adding it to an anti-IgE(H) antibody solution to form an anti-IgE(H) immunocomplex through a reaction of the Ce3 domain of the IgE antibody. The incubated solution was introduced onto the sensor chip and the immunocomplex of the IgE-anti-IgE(H) then reacted with the anti-IgE(D) antibody immobilized on the sensor chip through the Ce2 domain of the IgE antibody part of the IgE-anti-IgE(H) immunocomplex. The detection limit of the present method for the determination of the IgE antibody was about 10 ppb. The affinity constants for the anti-IgE(H) antibody immunocomplex with the IgE antibody in solution and that of the anti-IgE(H) antibody immunocomplex with the IgE antibody immobilized on the sensor chip by a biotin-streptavidin interaction were estimated to be 4.1 × 107 M-1 and 5.8 × 106 M-1, respectively. The affinity constant for the immunocomplex of the anti-IgE(H) antibody with the IgE antibody with the anti-IgE(D) immobilized on the sensor chip was estimated to be 4.9 × 107 M-1, 20-times larger than the affinity constant for the IgE antibody immunocomplex with the anti-IgE(D) antibody immobilized on the sensor chip, based on a direct immunoassay method of the IgE antibody under the same experimental conditions.. |
| 60. |
Koji Nakano, Electrical Transport Through DNA-Ferrocene Conjugate as Characterized by Conductive AFM Measurement, Proceedings of The 2nd International Symposium on Functional Innovation of Molecular Informatics, pp. 27, 2006.11. |
| 61. |
K. Nakano, G. Hirayama, M. Toguchi, K. Nakamura, K. Iwamoto, N. Soh, T. Imato, Poly(hydroquinone)-coated electrode for immobilizing of 5’-amine functioned capture probe DNA and electrochemical response to DNA hybridization, Science and Technology of Advanced Materials, https://doi.org/10.1016/j.stam.2006.06.007, 7, 7, 718-725, Vol. 7, No. 7, pp. 718 - 725., 2006.10, Enzymatically polymerized hydroquinone, PHQ, was applied for polymer-coated electrode whose surface was further modified with 5′-amine dodecamer DNAs (capture probe DNA, CP-DNA) by taking advantage of Michael reaction. The film-forming property of PHQ on graphite substrate surfaces was confirmed to be satisfactory by AFM imaging. Cyclic voltammetric (CV) measurements showed that the PHQ-modified graphite electrode gave well-defined redox waves showing characteristics for surface process. The pH dependence of the formal potential, E1/2, suggested that the electrode reaction occurred by two-proton and two-electron mechanism (−59 mV per a pH decade). CVs also gave the specific amount of PHQ adsorption of 0.52 or 0.83 nmol cm−2 (monomer unit) for the different electrode preparations. This was indicative of two- or three-monolayer adsorption of PHQ. For applications of gene detection, the immobilization reaction including the CP-DNA hybridization was studied by microgravimetric analysis using a quartz-crystal microbalance (QCM). Summaries for the two different runs were 1.01 and 0.69 nmol cm−2 (monomer unit) for PHQ adsorption on gold surfaces, 0.19 and 0.15 nmol cm−2 for CP-DNA attachment on the PHQ/Au, and 0.14 and 0.11 nmol cm−2 for hybridization with the complementary DNA on the CP-DNA/PHQ/Au, respectively. Importantly, monitoring of the series of the experiments were possible by measuring the voltammetric properties of the electrode; the distinct redox waves due to PHQ-electrode reaction are suppressed upon immobilizing of the CP-DNA, and its hybridization further suppressed the redox activity. Neither treating of the PHQ-electrode with native DNAs nor treating of CP-DNA/PHQ-electrode with non-target DNA gave no noticeable responses. A possible mechanism for the electrode response was discussed briefly based on electrochemical QCM measurements. We think these observations are important as the basis of DNA hybridization sensor that enables totally, label-free electrochemical detection of the target DNA.. |
| 62. |
K. Nakano, H. Matsunaga, K. Sai, N. Soh, T. Imato, Photoactive, covalent attachment of DNA on gold with double-strand specificity using self-assembled monolayers containing psoralen, Anal. Chim. Acta, https://doi.org/10.1016/j.aca.2006.04.085, 578, 1, 93-99, Vol. 578, No. 1, pp.93 - 99, 2006.09, Taking advantages of psoralen photochemistry, we have developed a new method of immobilizing DNA on gold substrate surfaces. A psoralen derivative having an alkylamine function was synthesized, and was self-assembled on gold substrate surfaces in a combined use of a thiol-derivatized molecule, 3,3′-dithiobis(succinimidyl propionate) forming amide bonds on the surface. We found that by irradiating with long wavelength ultraviolet light (320–400 nm), DNA molecules added in the solution phase were covalently immobilized on the monolayer surface through the photoadduct formation of the psoralen molecules with the DNA nucleobases. The present method has its advantage that is applicable to native DNAs, no chemically modifying DNAs, in spite of its covalent immobilization principle. We have examined 12 mer synthetic oligonucleotide immobilizations and have found that the surface concentration thus attained was to be 20 pmol cm−2, which is consistent with saturated surface coverage. Interestingly, the immobilization occurred double-stranded-DNA-preferentially; no immobilization for single-stranded DNAs. Characterization of the immobilization chemistry has been achieved using atomic force microscopic imaging, infrared absorption, X-ray photoelectron spectroscopy, electrochemistry, and quartz-crystal microbalance and their results were described.. |
| 63. |
Y. LI, M. KOBAYASHI, K. FURUI, N. SOH, K. NAKANO, T. IMATO, Surface plasmon resonance immunosensor for histamine based on an indirect competitive immunoreaction, Analytica Chimica Acta, https://doi.org/10.1016/j.aca.2006.01.078, 576, 1, 77-83, Vol. 576, No. 1, pp. 77 - 83, 2006.08, he use of a surface plasmon resonance immunosensor for the analysis of histamine (β-imidazole ethylamine) is described. The method is based on an indirect competitive reaction of an anti-histamine antibody in a sample solution with histamine immobilized on a sensor chip and with histamine in the sample solution. A sensor chip immobilized with histamine was prepared using a self-assembly monolayer of 11-mercaptoundecanoic acid (11-MUA) as an anchor membrane, followed by an amino-coupling reaction with histamine after activation of the 11-MUA layer on the sensor chip by treatment with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide. The sensor chip can be reused, after regeneration with a 10 mM HCl solution, which dissociates the anti-histamine antibody complex from histamine on the sensor chip. The affinity constants for the immunocomplex of the anti-histamine antibody with histamine in the solution and for that of the anti-histamine antibody with histamine immobilized on the sensor chip were calculated to be 1.5 × 107 and 7.2 × 105 M−1, respectively, by assuming a Langmuir-type adsorption of the anti-histamine antibody to histamine immobilized on the sensor chip. The detection limit of the method was determined to be 3 ppb.. |
| 64. |
Nobuaki Soh, Daisuke Seto, Koji Nakano, Toshihiko Imato, Novel fuorescent probe for detecting hydroperoxides with strong emission in the visible range, Molecular Biosystems, https://doi.org/10.1016/j.bmcl.2006.02.078, 16, 11, 81-84, Vol. 2, No. 2, pp. 81 - 84, 2006.06, A novel fluorescent probe, a swallow-tailed perylene derivative for detecting hydroperoxides (Spy-HP), containing perylene 3,4,9,10-tetracarboxyl bisimide as the main skeleton in the structure, was developed. Spy-HP reacted rapidly with hydroperoxides such as m-chloroperbenzoic acid (MCPBA) and cumene hydroperoxide to form its oxidized derivative, Spy-HPOx, and emitted an extremely strong fluorescence (Φ ∼ 1) in the visible range (λex = 524 nm and λem = 535 nm), as the result of canceling the photoinduced electron transfer (PET) effect. The reaction between Spy-HP and hydroperoxides proceeded quantitatively in strict stoichiometry, without being affected by autoxidation or photobleaching. Because of these prominent properties, Spy-HP is expected to be a novel and useful fluorescent probe to ‘spy’ on hydroperoxides in biosamples.. |
| 65. |
K. Hirakawa, M. Katayama, N. Soh, K. Nakano, H. Ohura, S. Yamasaki, T. Imato, Electrochemical Sandwich Immunoassay for Vitellogenin by Sequential Injection Analysis Using Antibody Immobilized Magnetic Microbeads, Electroanalysis, https://doi.org/10.1002/elan.200603529, 18, 13-14, 1297-1305, Vol. 18, No. 13-14, pp. 1297 - 1305, 2006.06, A rapid and sensitive sandwich immunoassay based on a sequential injection analysis (SIA) for the determination of carp vitellogenin (Vg) is described. The SIA system was constructed from a syringe pump, a multiposition valve, a flow-through type immunoreaction cell equipped with a magnet and an amperometric detector. Magnetic microbeads immobilized with an anti-Vg monoclonal antibody (primary antibody) were used as a solid support. The primary antibody was immobilized on magnetic microbeads by coupling the primary antibody with a polylactic acid-layer, which was coated on the surface of the magnetic beads, after activated with N-hydroxysuccinimide. The introduction, trapping and flushing out of the magnetic microbeads in the immunoreaction cell were controlled by the magnet and the flow of the carrier solution. After the primary antibody-immobilized magnetic beads were introduced and trapped in the immunoreaction cell, a Vg sample solution, an alkaline phosphatase (AP)-labeled anti-Vg polyclonal antibody (secondary antibody) solution and a p-aminophenyl phosphate (PAPP) solution were sequentially introduced into the immunoreaction cell based on an SIA programmed sequence. Vg was determined by the electrochemical detection of p-aminophenol (PAP), an enzymatic product of PAPP via the action by AP labeled on the secondary antibody. A solution containing PAP, which was generated in the immunoreaction cell and transiently held in a holding coil, was transported to the amperometric detector and the oxidation current of PAP on a working electrode applied at +0.20 V was measured. A sigmoidal calibration curve was obtained in the concentration range from 1 ppb to 500 ppb in a plot of oxidation current against the logarithm of the Vg concentration. The lower detection limit of the immunoassay was about 2–3 ppb. The time required for an analysis was ca. 15 min/sample.. |
| 66. |
N. SOH, D. SETO, K. NAKANO, T. IMATO, Methodology of reversible protein labeling for ratiometric fluorescent measurement, Molecular BioSystems, DOI https://doi.org/10.1039/B515777C, 2, 2, 128-131, Vol. 2, No. 2, pp. 128 - 131, 2006.02, The first fluorescent labeling technology, which can induce not only an increase in the fluorescence intensity but also a shift in the fluorescence spectrum, has been developed for “ratiometric” measurements for a protein by utilizing a newly designed “field-sensitive” fluorescent probe and its corresponding unique amino acid tag.. |
| 67. |
K. HIRAKAWA, M. KATAYAMA, N. SOH, K. NAKANO, T. IMATO, Electrochemical Immunoassay for Vitellogenin Based on Sequential Injection Using Antigen-immobilized Magnetic Microbeads, Analytical Sciences, https://doi.org/10.2116/analsci.22.81, 22, 1, 81-86, Vol 22, No. 2, pp.81 - 86, 2006.01, A rapid and sensitive immunoassay for the determination of vitellogenin (Vg) is described. The method involves a sequential injection analysis (SIA) system equipped with an amperometric detector and a neodymium magnet. Magnetic beads, onto which an antigen (Vg) was immobilized, were used as a solid support in an immunoassay. The introduction, trapping and release of magnetic beads in an immunoreaction cell were controlled by means of the neodymium magnet and by adjusting the flow of the carrier solution. The immunoassay was based on an indirect competitive immunoreaction of an alkaline phosphatase (ALP) labeled anti-Vg monoclonal antibody between the fraction of Vg immobilized on the magnetic beads and Vg in the sample solution. The immobilization of Vg on the beads involved coupling an amino group moiety of Vg with the magnetic beads after activation of a carboxylate moiety on the surface of magnetic beads that had been coated with a polylactate film. The Vg-immobilized magnetic beads were introduced and trapped in the immunoreaction cell equipped with the neodymium magnet; a Vg sample solution containing an ALP labeled anti-Vg antibody at a constant concentration and a p-aminophenyl phosphate (PAPP) solution were sequentially introduced into the immunoreaction cell. The product of the enzyme reaction of PAPP with ALP on the antibody, p-aminophenol, was transported to an amperometric detector, the applied voltage of which was set at +0.2 V vs. an Ag/AgCl reference electrode. A sigmoid calibration curve was obtained when the logarithm of the concentration of Vg was plotted against the peak current of the amperometric detector using various concentrations of standard Vg sample solutions (0 - 500 ppb). The time required for the analysis is less than 15 min.. |
| 68. |
Koji NAKANO, Hideshi MATSUNAGA, Keisuke SAI, Covalent attachment of DNA with double-strand specificity using self-assembled monolayers from psoralen, Proceedings of The 2005 International Chemical Congress of Pacific Basin Societies, pp. 366, 2005.12. |
| 69. |
Hideshi MATSUNAGA, Koji NAKANO, Nobuaki SOH, Toshihiko IMATO, Preparation, Characterization and Atomic Force Microscopic Imaging of New DNA Ligand for Single Molecular Hybridization Assay, Proceedings of The 2005 International Chemical Congress of Pacific Basin Societies, pp. 968, 2005.12. |
| 70. |
Koji NAKANO, Go HIRAYAMA, Mikiko TOGUCHI, Kaori NAKAMURA, Kaori IWAMOTO, Nobuaki SOH, Toshihiko IMATO, DNA Conjugate Electrode Having DNA/Oligo(1,4-hydroquinone)/PG Interfacial Structure for Biosensor Applications: Characterization by Electrochemical Measurements, QCM Analysis, and AFM Imaging, Program & Abstracts for the 8th Asian Conference on Analytical Sciences, pp. 138, 2005.10. |
| 71. |
R-Q. Zhang, K. Hirakawa, D. Seto, N. Soh, K. Nakano, T. Masadome, K. Nagata, K. Sakamoto, T. Imato, Sequential injection chemiluminescence immunoassay for anionic surfactants using magnetic microbeads immobilized with an antibody., Talanta, 10.1016/j.talanta.2005.07.012, 68, 2, 231-238, VOL. 68, No. 2, pp. 231 - 238, 2005.10, A rapid and sensitive immunoassay for the determination of linear alkylbenzene sulfonates (LAS) is described. The method involves a sequential injection analysis (SIA) system equipped with a chemiluminescence detector and a neodymium magnet. Magnetic beads, to which an anti-LAS monoclonal antibody was immobilized, were used as a solid support in an immunoassay. The introduction, trapping and release of the magnetic beads in the flow cell were controlled by means of a neodymium magnet and adjusting the flow of the carrier solution. The immunoassay was based on an indirect competitive immunoreaction of an anti-LAS monoclonal antibody on the magnetic beads and the LAS sample and horseradish peroxidase (HRP)-labeled LAS, and was based on the subsequent chemiluminscence reaction of HRP with hydrogen peroxide and p-iodophenol, in a luminol solution. The anti-LAS antibody was immobilized on the beads by coupling the antibody with the magnetic beads after activation of a carboxylate moiety on the surface of magnetic beads that had been coated with a polylactic acid film. The antibody immobilized magnetic beads were introduced, and trapped in the flow cell equipped with the neodymium magnet, an LAS solution containing HRP-labeled LAS at constant concentration and the luminol solution were sequentially introduced into the flow cell based on an SIA programmed sequence. Chemiluminescence emission was monitored by means of a photon counting unit located at the upper side of the flow cell by collecting the emitted light with a lens. A typical sigmoid calibration curve was obtained, when the logarithm of the concentration of LAS was plotted against the chemiluminescence intensity using various concentrations of standard LAS samples (0–500 ppb) under optimum conditions. The time required for analysis is less than 15 min.. |
| 72. |
T. TSURUTA, Y. KATSUMI, S. SHIRAKAWA, S. TAGUCHI, K. NAKANO, Synthesis of New Psoralen Derivatives for Chemical Modification and Functionalization of DNA Duplexes as Characterized by Gel Electrophoresis, IR, QCM, Electrochemistry, and AFM, Abstract Book of International Symposium on Nano-organization and Function, 2004.11. |
| 73. |
H. MATSUNGAE, K. SAI, K. NAKANO, Covalent Attachment of Double-Stranded DNA using Self-Assembled Monolayers Containing Psoralen as Characterized by XPS, IR, QCM, Electrochemistry, and AFM, Abstract Book of International Symposium on Nano-organization and Function, pp. 48, 2004.11. |
| 74. |
K. NAKANO, K. DOI, K. TAMURA, Y. KATSUMI, Monolayer Formation of Glucose Oxidase Covalently Attached on ω-Aminoalkanethiol/Au via Activation of Carbohydrate Residue of GOx as Characterized by AFM, IR, QCM, and Biosensor Applications, Abstract of The 7th Asian Conference on Analytical Sciences, pp. 308, 2004.10. |
| 75. |
T. Anada, H. Matsunaga, R. Karinaga, K. Koumoto, M. Mizu, K. Nakano, S. Shinkai, and K. Sakuraia, Proposal of new modification technique for linear double-stranded DNAs using the polysaccharide schizopyllan, Bioorganic & Medicinal Chemistry Letters, 10.1016/j.bmcl.2004.08.043, 14, 22, 5655-5659, Vol.14, pp.5655 - 5659, 2004.09. |
| 76. |
K. Nakano, S. Shirakawa, S. Taguchi, A psoralen Derivative Containing Ferrocene for Redox-labeling of DNA and Electrochemical Gene Sensor Applications, Chemcial Sensors, Vol. 20, Supplement B, pp. 778 - 779., 2004.07. |
| 77. |
Koji Nakano, DNA-Ferrocene Conjugate for Nanoelectronic Material Applications. Atomic Force Microscope-Based, Direct Measurement of Electrical Transport through DNA Molecules, Second 21st Century COE “Towards Creating New Industries Based on Inter-Nanoscience” and 7th SANKEN International Symposium on “Hybridization of Chemistry, Biology, and Material Science”, pp. 38 - 39, 2004.01. |
| 78. |
K. Nakano, K. Doi, K. Tamura, Y. Katsumi, Self-Assembling Monolayer Formation of Glucose Oxidase and Cytochrome c Covalently Attached on Alkanethiol Monolayers on Gold, Biomolecular Chemistry. Proceedings of the ISBC 2003, pp. 284 - 285, 2003.12. |
| 79. |
K. NAKANO, K. DOI, K. TAMURA, Y. KATSUMI, Self-assembling Monolayer Formation of Glucose Oxidase Covalently Attached on 11-Aminoundecanethiol Monolayers on Gold, Chemical Communications, 10.1039/b303298a, 13, 1544-1545, Vol. 2003, No. 13, pp. 1544 - 1545, 2003.06, Glucose oxidase (GOx) has been attached covalently to form uniform enzyme monolayers on self-assembled monolayers (SAMs) from 11-aminoundecanethiol (AUDT) by taking advantage of chemical oxidation of GOx carbohydrate residues followed by coupling the resulting ‘aldehydic’ enzyme with the terminal amino group in the SAM as characterized by AFM imaging, IR, QCM, and electrochemical measurements.
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