| 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. |
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.. |
| 3. |
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. |
| 4. |
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.. |
| 5. |
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. |
| 6. |
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. |
| 7. |
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. |
| 8. |
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. |
| 9. |
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.. |
| 10. |
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.. |
| 11. |
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.. |
| 12. |
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.. |
| 13. |
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.. |
| 14. |
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.. |
| 15. |
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.. |
| 16. |
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.. |
| 17. |
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.
. |
| 18. |
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.. |
| 19. |
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.. |
| 20. |
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.. |
| 21. |
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. |
| 22. |
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.. |
| 23. |
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.. |
| 24. |
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.. |
| 25. |
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.. |
| 26. |
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.. |
| 27. |
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.. |
| 28. |
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.. |
| 29. |
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. |
| 30. |
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. |
| 31. |
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. |
| 32. |
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..  |
| 33. |
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. |
| 34. |
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. |
| 35. |
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. |
| 36. |
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. |
| 37. |
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. |
| 38. |
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. |
| 39. |
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. |
| 40. |
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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