研究者詳細 - 金田　隆

論文 - 金田　隆

分割表示 133 件中 41 - 60 件目／全件表示 >>

Enhanced collection efficiency of vesicles in a suspension by optical pressure using gold nanoparticles 査読

Takashi Kaneta, Mai Kuboi, Nobuyuki Takeyasu

OPTICAL MANIPULATION CONFERENCE 10712 2018年

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING

We developed a method to collect micro- and nano-vesicles on a glass substrate using the optical pressure of a laser beam. The laser beam was focused on the glass substrate which sandwiches a suspension containing micro- or nano-sized vesicles prepared by a phospholipid. The optical pressure generated at the interface of the medium and the vesicles accelerated the vesicles to form aggregates on the glass surface. Two types of glass substrates, hydrophilic and aminated ones, showed no difference in the adsorption property of the vesicles. Time to be required for collecting a certain amount of the vesicles was inversely proportional to the concentration of the vesicles. To enhance the collection efficiency, gold nanoparticles were added to the suspension of the vesicles. We found that gold nanoparticles reduced the collection time as short as 1/10-times.

DOI： 10.1117/12.2317724

Paper-based analytical devices

Daniel Citterio, Takashi Kaneta

Analytical Sciences 34 ( 1 ) 5 - 6 2018年

Simultaneous Determination of Manganese Peroxidase and Lignin Peroxidase by Capillary Electrophoresis Enzyme Assays 査読

Sumire Kudo, Airi Harada, Hiroe Kubota, Keiko Sasaki, Takashi Kaneta

ACS OMEGA 2 ( 10 ) 7329 - 7333 2017年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Here, we developed an enzyme assay of manganese peroxidase (MnP) by capillary electrophoresis using an in-capillary reaction and applied it to a simultaneous assay of MnP and lignin peroxidase (LiP). The enzyme activity of MnP was determined from the peak area corresponding to Mn(III)-malonate produced by the plug-plug reaction between MnP and Mn(II) in a separation capillary. A background electrolyte containing 250 mM malonate buffer (pH 4.5) and 5 mM cetyltrimethylammonium bromide was employed for the separation of Mn(III)-malonate from MnP at-10 kV after a plug-plug reaction for 5 min. Although the assay permitted the determination of purified MnP, we found that both LiP and MnP have similar activities against their substrates, that is, LiP catalyzed the oxidation reaction of Mn(II) as well as MnP, whereas MnP catalyzed the oxidation reaction of veratryl alcohol which was the substrate used in the LiP assay developed previously. Thus, we proposed a method to discriminate MnP from LiP based on the difference in the activities of these enzymes to each substrate. Amounts of MnP and LiP in a mixture were successfully evaluated by the proposed method.

DOI： 10.1021/acsomega.7b00998

Temperature-induced Coalescence of Droplets Manipulated by Optical Trapping in an Oil-in-Water Emulsion 査読

Manami Mitsunobu, Sakurako Kobayashi, Nobuyuki Takeyasu, Takashi Kaneta

ANALYTICAL SCIENCES 33 ( 6 ) 709 - 713 2017年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPAN SOC ANALYTICAL CHEMISTRY

Coalescence of oil droplets in an oil-in-water (O/W) emulsion was achieved with heating and optical trapping. Three types of O/W emulsions were prepared by adding a mixture of butanol and n-decane to an aqueous solution containing a cationic surfactant (cetyltrimethylammonium bromide, CTAB), an anionic surfactant (sodium dodecyl sulfate, SDS), or a neutral hydrophilic polymer (polyethylene glycol, PEG) as an emulsifier. Two oil droplets in the emulsions were randomly trapped in a square capillary tube by two laser beams in order to induce coalescence. Coalescence of the droplets could not be achieved at room temperature (25 degrees C) regardless of the type of emulsifier. Conversely, the droplets prepared with PEG coalesced at a temperature higher than 30 degrees C, although the droplets with ionic surfactants CTAB and SDS did not coalesce even at the elevated temperature due to their electrostatic repulsion. The size of the resultant coalesced droplet was consistent with that calculated from the size of the two droplets of oil, which indicated successful coalescence of the two droplets. We also found that the time required for the coalescence could be correlated with the temperature using an Arrhenius plot.

DOI： 10.2116/analsci.33.709

Bio-modification of carbonaceous matter in gold ores: Model experiments using powdered activated carbon and cell-free spent medium of Phanerochaete chrysosporium 査読

Kojo T. Konadu, Keiko Sasaki, Takashi Kaneta, Grace Ofori-Sarpong, Kwadwo Osseo-Asare

HYDROMETALLURGY 168 76 - 83 2017年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Carbonaceous matter in refractory gold ore is known to be one of the primary causes of gold recovery loss. Model experiments were conducted to simulate the bio-modification of carbonaceous matter using powdered activated carbon (PAC) as a surrogate and cell-free spent medium (CFSM) of Phanerochaete chrysosporium. The CFSM was used because of the lignin peroxidase and manganese peroxidase secreted by the microbe during its incubation. In the present work, an investigation was conducted to determine the physical and chemical alterations in PAC after enzymatic treatment and its effect on Au(CN)(2)(-) uptake. Characterization of the solid residues of PAC by C-13 NMR and N-2 adsorption after bio-modification revealed that the treatment had decomposed poly-aromatic carbons into aliphatic carbons and also reduced the specific surface area from 1430 m(2)/g to 697 m(2)/g in 14 days. As a result, Au(CN)(2)(-) uptake decreased from 100% (0.048 mmol/g) to 43% within 12 h primarily due to the enzyme treatment and adsorption of CFSM components. It further decreased to 26% due to surface passivation by bio-chemicals derived from CFSM and/or decomposed aliphatic hydrocarbons from aromatic carbons between 7 days and 14 days. These findings may contribute to efforts to decrease preg-robbing in hydrometallurgical processing of refractory gold ores. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.hydromet.2016.08.003

Enzymatic pre-treatment of carbonaceous matter in preg-robbing gold ores: Effect of ferrous ion additives 査読

Kojo T. Konadu, Keiko Sasaki, Kwadwo Osseo-Asare, Takashi Kaneta

Solid State Phenomena 262 43 - 47 2017年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Trans Tech Publications Ltd

The bio-treatment of double refractory gold ores (DRGO) to reduce preg-robbing needs to account for the heterogeneity of the ore so as to acquire a much more complete picture of the system. To this end, the effects of ferrous ion additives on the degradation of powdered activated carbon (PAC) by cell-free spent medium (CFSM) was studied. Au(CN)2- adsorption and Raman spectrometric results suggest that the ferrous salt could have possibly reacted with some biogenic hydrogen peroxide to aid in the degradation of PAC. The bio-treatment produced mixed solid residues containing some partially degraded aromatic compounds which were soluble in alkaline solutions. Ultimately, biodegradation of PAC using CFSM in the presence of 50 µM FeSO4.7H2 O for 7 days followed by washing with 3 mM NaOH reduced Au(CN)2- uptake by 80%.

DOI： 10.4028/www.scientific.net/SSP.262.43

Chelate titrations of Ca2+ and Mg2+ using microfluidic paper-based analytical devices 査読

Shingo Karita, Takashi Kaneta

ANALYTICA CHIMICA ACTA 924 60 - 67 2016年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

We developed microfluidic paper-based analytical devices (mu PADs) for the chelate titrations of Ca2+ and Mg2+ in natural water. The mu PAD consisted of ten reaction zones and ten detection zones connected through narrow channels to a sample zone located at the center. Buffer solutions with a pH of 10 or 13 were applied to all surfaces of the channels and zones. Different amounts of ethylenediaminetetraacetic acid (EDTA) were added to the reaction zones and a consistent amount of a metal indicator (Eriochrome Black T or Calcon) was added to the detection zones. The total concentrations of Ca2+ and Mg2+ (total hardness) in the water were measured using a mu PAD containing a buffer solution with a pH of 10, whereas only Ca2+ was titrated using a mu PAD prepared with a potassium hydroxide solution with a pH of 13. The mu PADs permitted the determination of Ca2+ and Mg2+ in mineral water, river water, and seawater samples within only a few minutes using only the naked eye-no need of instruments. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.aca.2016.04.019

Direct determination of lignin peroxidase released from Phanerochaete chrysosporium by in-capillary enzyme assay using micellar electrokinetic chromatography 査読

Airi Harada, Keiko Sasaki, Takashi Kaneta

JOURNAL OF CHROMATOGRAPHY A 1440 145 - 149 2016年4月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Here we describe the application of an in-capillary enzyme assay using micellar electrokinetic chromatography (MEKC) in the determination of enzyme activity in a crude culture medium containing lignin peroxidase released from Phanerochaete chrysosporium (P. chrysosporium). The method consists of a plug-plug reaction between lignin peroxidase and its substrate, veratryl alcohol, the separation of the product, veratraldehyde, from the other components including the enzyme and the culture medium, and the determination of the enzyme activity from the peak area of veratraldehyde produced by the plug-plug reaction. This method is more sensitive than conventional spectrophotometry since the background originates from the enzyme and the culture medium can be removed via MEKC separation. Veratraldehyde was separated at-10 kV in a background electrolyte containing 50mM tartrate buffer (pH 2.5) and 50 mM sodium dodecyl sulfate (SDS) after a plug-plug reaction in the capillary for 5 min. The calibration curve of veratraldehyde was linear up to 4pmol (500 mu M) with a limit to quantification of 0.026 pmol (3.211 mu M) (SN = 10). The activity of lignin peroxidase was directly measured from the peak area of veratraldehyde. The activity of lignin peroxidase released from P. chrysosporium into the medium for 7 days was successfully determined to be 3.40 UL-1. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chroma.2016.02.062

Determination of Iron Ion in the Water of a Natural Hot Spring Using Microfluidic Paper-based Analytical Devices 査読

Kazuma Ogawa, Takashi Kaneta

ANALYTICAL SCIENCES 32 ( 1 ) 31 - 34 2016年1月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPAN SOC ANALYTICAL CHEMISTRY

Microfluidic paper-based analytical devices (mu PADs) were used to detect the iron ion content in the water of a natural hot spring in order to assess the applicability of this process to the environmental analysis of natural water. The mu PADs were fabricated using a wax printer after the addition of hydroxylamine into the detection reservoirs to reduce Fe3+ to Fe2+, 1,10-phenanthroline for the forming of a complex, and poly(acrylic acid) for ion-pair formation with an acetate buffer (pH 4.7). The calibration curve of Fe3+ showed a linearity that ranged from 100 to 1000 ppm in the semi-log plot whereas the color intensity was proportional to the concentration of Fe3+ and ranged from 40 to 350 ppm. The calibration curve represented the daily fluctuation in successive experiments during four days, which indicated that a calibration curve must be constructed for each day. When freshly prepared mu PADs were compared with stored ones, no significant difference was found. The mu PADs were applied to the determination of Fe3+ in a sample of water from a natural hot spring. Both the accuracy and the precision of the mu PAD method were evaluated by comparisons with the results obtained via conventional spectrophotometry. The results of the mu PADs were in good agreement with, but less precise than, those obtained via conventional spectrophotometry. Consequently, the mu PADs offer advantages that include rapid and miniaturized operation, although the precision was poorer than that of conventional spectrophotometry.

DOI： 10.2116/analsci.32.31

A miniaturized chemiluminescence detection system for a microfluidic paper-based analytical device and its application to the determination of chromium(III) 査読

Waleed Alahmad, Kanchana Uraisin, Duangjai Nacapricha, Takashi Kaneta

ANALYTICAL METHODS 8 ( 27 ) 5414 - 5420 2016年

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

A miniaturized detection system for chemiluminescence that is generated on a microfluidic paper-based analytical device (mu PAD) was developed using optical fibers and was applied to the determination of Cr(III). The mPAD was fabricated by wax printing and consisted of 6 separate channels in a parallel alignment. Each channel was composed of an injection zone for a reagent solution, a reaction zone, and a waste zone. The mu PAD was placed on a plastic holder equipped with 6 optical fibers to collect chemiluminescence (CL). The other ends of the optical fibers were bundled and introduced into a small photomultiplier tube module to obtain the CL signals. The CL reaction was based on luminol oxidation by hydrogen peroxide in the presence of Cr(III), which catalyzed the reaction in an alkaline medium. The reaction conditions, including the use of an enhancer and a masking agent, were optimized to obtain high sensitivity and selectivity. Under the optimal conditions, a linear range was obtained at 0.05 to 1.00 ppm with a detection limit of 0.02 ppm. The analysis time was less than 1 min per one mu PAD in order to obtain 6 measurements of differing concentrations with a precision of < 6.5%. This method was successfully applied to the determination of Cr(III) spiked into natural water samples at the sub-ppm range.

DOI： 10.1039/c6ay00954a

Capillary Electrophoresis with Laser-induced Fluorescence Detection for Application in Intracellular Investigation of Anthracyclines and Multidrug Resistance Proteins 査読

Julius Mbuna, Takashi Kaneta

ANALYTICAL SCIENCES 31 ( 11 ) 1121 - 1128 2015年11月

記述言語：英語出版者・発行元：JAPAN SOC ANALYTICAL CHEMISTRY

Capillary electrophoresis (CE) coupled with laser-induced fluorescence (LIF) is a powerful method for the trace analysis of cellular components. This review presents a summary of topics for the direct analysis of anthracyclines and multidrug resistance proteins in cancerous cells. A micellar electrokinetic chromatography (MEKC) method that does not use organic solvents, and hence prevents the precipitation of proteins in cellular samples, was shown to be a reliable method for the determination of several anthracyclines including the epimeric doxorubicin and epirubicin. A fast CE-based immunoassay for investigating transporter multidrug resistance associated protein (MRP1) was also developed for routine or explorative analysis of the levels of transporter proteins in cancerous cells. A combination of the developed MEKC-LIF method and the CE immunoassay (CEIA) method has permitted the analysis of anthracyclines and MRP1 in a cell line to show the relationship between the levels of MRP1 and amount of anthracyclines in cancerous cells.

DOI： 10.2116/analsci.31.1121

Capillary Electrophoresis with Laser-induced Fluorescence Detection for Application in Intracellular Investigation of Anthracyclines and Multidrug Resistance Proteins 査読

Julius Mbuna, Takashi Kaneta

ANALYTICAL SCIENCES 31 ( 11 ) 1121 - 1128 2015年11月

記述言語：英語出版者・発行元：JAPAN SOC ANALYTICAL CHEMISTRY

Capillary electrophoresis (CE) coupled with laser-induced fluorescence (LIF) is a powerful method for the trace analysis of cellular components. This review presents a summary of topics for the direct analysis of anthracyclines and multidrug resistance proteins in cancerous cells. A micellar electrokinetic chromatography (MEKC) method that does not use organic solvents, and hence prevents the precipitation of proteins in cellular samples, was shown to be a reliable method for the determination of several anthracyclines including the epimeric doxorubicin and epirubicin. A fast CE-based immunoassay for investigating transporter multidrug resistance associated protein (MRP1) was also developed for routine or explorative analysis of the levels of transporter proteins in cancerous cells. A combination of the developed MEKC-LIF method and the CE immunoassay (CEIA) method has permitted the analysis of anthracyclines and MRP1 in a cell line to show the relationship between the levels of MRP1 and amount of anthracyclines in cancerous cells.

DOI： 10.2116/analsci.31.1121

Investigation of surface-enhanced Raman scattering spectra of p-ATP at different laser excitation powers

Nobuyuki Takeyasu, Ryusuke Kagawa, Takashi Kaneta

Optics InfoBase Conference Papers 2019 2015年

Acid-Base Titrations Using Microfluidic Paper-Based Analytical Devices 査読

Shingo Karita, Takashi Kaneta

ANALYTICAL CHEMISTRY 86 ( 24 ) 12108 - 12114 2014年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Rapid and simple acid-base titration was accomplished using a novel microfluidic paper-based analytical device (mu PAD). The mu PAD was fabricated by wax printing and consisted of ten reservoirs for reaction and detection. The reaction reservoirs contained various amounts of a primary standard substance, potassium hydrogen phthalate (KHPth), whereas a constant amount of phenolphthalein was added to all the detection reservoirs. A sample solution containing NaOH was dropped onto the center of the mu PAD and was allowed to spread to the reaction reservoirs where the KHPth neutralized it. When the amount of NaOH exceeded that of the KHPth in the reaction reservoirs, unneutralized hydroxide ion penetrated the detection reservoirs, resulting in a color reaction from the phenolphthalein. Therefore, the number of the detection reservoirs with no color change determined the concentration of the NaOH in the sample solution. The titration was completed within 1 min by visually determining the end point, which required neither instrumentation nor software. The volumes of the KHPth and phenolphthalein solutions added to the corresponding reservoirs were optimized to obtain reproducible and accurate results for the concentration of NaOH. The mu PADs determined the concentration of NaOH at orders of magnitude ranging from 0.01 to 1 M. An acid sample, HCl, was also determined using Na2CO3 as a primary standard substance instead of KHPth. Furthermore, the mu PAD was applicable to the titrations of nitric acid, sulfuric acid, acetic acid, and ammonia solutions. The mu PADs were stable for more than 1 month when stored in darkness at room temperature, although this was reduced to only 5 days under daylight conditions. The analysis of acidic hot spring water was also demonstrated in the field using the mu PAD, and the results agreed well with those obtained by classic acid-base titration.

DOI： 10.1021/ac5039384

Method development for the determination of mercury(II) by sequential injection/anodic stripping voltammetry using an in situ gold-film screen-printed carbon electrode 査読

Eakkasit Punrat, Suchada Chuanuwatanakul, Takashi Kaneta, Shoji Motomizu, Orawon Chailapakul

JOURNAL OF ELECTROANALYTICAL CHEMISTRY 727 78 - 83 2014年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE SA

A computer-controlled system, included a sequential injection system and an electrochemical detector, was developed for the determination of mercury(II) ion (Hg2+) concentrations. The screen-printed carbon electrode (SPCE), a well-known low-cost electrode, was modified by overlaying in situ with a gold film (Au-SPCE). Square wave anodic stripping voltammetry (SWASV) using the Au-SPCE was performed with a two-step deposition potential of an initial -0.5 V vs Ag/AgCl for the preparation of the gold film and then a deposition potential of +0.2 V vs Ag/AgCl for the preconcentration of mercury. An on-line medium exchange method was included in the injection step to reduce the effect of chloride ions, whilst a solid phase extraction cartridge was used to remove interference for copper(II) ions. The flow pattern of the sequentially injected solutions with the synchronized two-step deposition potentials did not significantly affect the detection of Hg2+. Square wave parameters of a 4 mV step potential, 150 Hz frequency and 30 mV amplitude gave an optimal Hg2+ detection sensitivity with a limit of detection of 0.22 mu g L-1 (sample volume of 0.9 mL) without any significant interference effect. This method was successfully applied to determine Hg2+ concentrations in real water samples, including in the chloride-rich samples of sea water and table salt, with very good accuracy (recovery in the range of 96.0-101%). (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jelechem.2014.05.026

Speciation of arsenic in a thermoacidophilic iron-oxidizing archaeon, Acidianus brierleyi, and its culture medium by inductively coupled plasma-optical emission spectroscopy combined with flow injection pretreatment using an anion-exchange mini-column 査読国際誌

Naoki Higashidani, Takashi Kaneta, Nobuyuki Takeyasu, Shoji Motomizu, Naoko Okibe, Keiko Sasaki

TALANTA 122 240 - 245 2014年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER

The thermoacidophilic iron-oxidizing archaeon Acidianus brierleyi is a microorganism that could be useful in the removal of inorganic As from wastewater, because it simultaneously oxidizes As(III) and Fe(II) to As(V) and Fe(III) in an acidic culture medium, resulting in the immobilization of As(V) as FeAsO4. To investigate the oxidation mechanism, speciation of the As species in both the cells and its culture media is an important issue. Here we describe the successive determination of As(III), As(V), and total As in A. brierleyi and its culture medium via a facile method based on inductively coupled plasma-optical emission spectroscopy (ICP-OES) with a flow injection pretreatment system using a mini-column packed with an anion-exchange resin. The flow-injection pretreatment system consisted of a syringe pump, a selection valve, and a switching valve, which were controlled by a personal computer. Sample solutions with the pH adjusted to 5 were flowed into the mini-column to retain the anionic As(V), whereas As(III) was introduced into ICP-OES with no adsorption on the mini-column due to its electrically neutral form. An acidic solution (I M HNO3) was then flowed into the mini-column to elute As(V) followed by ICP-OES measurement. The same sample was also subjected to ICP-OES without being passed through the mini-column in order to determine the total amounts of As(III) and As(V). The method was verified by comparing the results of the total As with the sum of As(III) and As(V). The calibration curves showed good linearity with limits of detection of 158, 86, and 211 ppb for As(III), As(V), and total As, respectively. The method was successfully applicable to the determination of the As species contained in the pellets of A. brierleyi and their culture media. The results suggested that the oxidation of As(III) was influenced by the presence of Fe(II) in the culture medium, i.e., Fe(II) enhanced the oxidation of As(III) in A. brierleyi. In addition, we found that no soluble As species was contained in the cell pellets and more than 60% of the As(III) in the culture medium was oxidized by A. brierleyi after a 6-day incubation. (c) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.talanta.2014.01.057

Method development for the determination of arsenic by sequential injection/anodic stripping voltammetry using long-lasting gold-modified screen-printed carbon electrode 査読

Eakkasit Punrat, Suchada Chuanuwatanakul, Takashi Kaneta, Shoji Motomizu, Orawon Chailapakul

TALANTA 116 1018 - 1025 2013年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

An automated method has been developed for determining the concentration of inorganic arsenic. The technique uses sequential injection/anodic stripping voltammetry with a long-lasting gold-modified screen-printed carbon electrode. The long-lasting gold electrode was electrochemically deposited onto a screen-printed carbon electrode at a potential of -0.5 V vs. Ag/AgCl in a supporting electrolyte solution of 1 M hydrochloric acid. Under optimal conditions and the applied potentials, the electrode demonstrated that it can be used for a long time without a renewal process. The linear range for the determination of arsenic(III) was 1-100 mu g L-1, and the limit of detection (LOD) in standard solutions was as low as 0.03 mu g L-1 for a deposition time of 120 s and sample volume of 1 mL. This method was used to determine the concentration of arsenic(III) in water samples with satisfactory results. The LOD in real samples was found to be 0.5 mu g L-1. In addition, speciation between arsenic(III) and arsenic(V) has been achieved with the proposed method using deposition potentials of -0.5 V and -1.5 V for the determination of the arsenic(III) concentration and the total arsenic concentration, respectively; the results were acceptable. The proposed method is an automated system that offers a less expensive alternative for determining trace amounts of inorganic arsenic. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.talanta.2013.08.030

Discrimination of glycoproteins via two-color laser-induced fluorescence detection coupled with postcolumn derivatization in capillary electrophoresis 査読

Ayumi Tabara, Takashi Kaneta

ELECTROPHORESIS 34 ( 16 ) 2316 - 2322 2013年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY

Here, we report a novel method consisting of capillary electrophoretic separation followed by two-color LIF detection with postcolumn derivatization. The method can be used to discriminate glycoproteins in a protein mixture containing both glycosylated and unglycosylated proteins. The detector permitted simultaneous measurements of two electropherograms obtained by 450 nm (diode laser) and 532 nm (Nd:YAG laser) lasers excited native proteins following postcolumn derivatization with naphthalene-2,3-dicarboxaldehyde and concanavalin A (Con A) labeled with tetramethylrhodamine (rhodamine-labeled Con A), respectively. So, a protein can be assigned as glycosylated if it shows a peak at the same migration time in both electropherograms. According to the proposed principle, in a single run we discriminated a glycosylated protein (thyroglobulin) from an unglycosylated protein (albumin) in the presence of rhodamine-labeled Con A. Because the methodology permits the simultaneous detection of native proteins and their complexes with a fluorescently labeled probe, it should have broad applicability to binding assays.

DOI： 10.1002/elps.201300149

Determination of Acid Dissociation Constant of Degradable Tetrabromophenolphthalein Ethyl Ester by Capillary Zone Electrophoresis 査読

Toshio Takayanagi, Ayumi Tabara, Takashi Kaneta

ANALYTICAL SCIENCES 29 ( 5 ) 547 - 552 2013年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPAN SOC ANALYTICAL CHEMISTRY

An acid dissociation constant of tetrabromophenolphthalein ethyl ester (TBPE) was determined through the measurement of electrophoretic mobility by capillary zone electrophoresis (CZE). Although TBPE is degradable in acidic pH region and it gradually degraded at pH conditions around and below its pK(a) values in the time scale of the CZE measurement, equilibrium species of interest were detected as a peak-shaped signal with tailing of the degraded species. Changes in electrophoretic mobility of the equilibrium species of TBPE were analyzed at its detectable pH range in the presence of phenol red as a mobility standard. An acid dissociation constant of 3.47 +/- 0.06 (pK(a), I = 0.01, 25 degrees C, standard error) was determined for TBPE.

DOI： 10.2116/analsci.29.547

Determination of association constants between 5 '-guanosine monophosphate gel and aromatic compounds by capillary electrophoresis 査読

Kaori Yamaguchi, Nobuyuki Takeyasu, Takashi Kaneta

JOURNAL OF CHROMATOGRAPHY A 1288 149 - 154 2013年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER

Hydro gel formed by 5'-guanosine monophosphate (GMP) in the presence of a potassium ion is expected to exhibit interesting selectivity in capillary electrophoretic separations. Here, we estimated the conditional association constants between the hydro gel (G-gel) and aromatic compounds by capillary electrophoresis in order to investigate the separation selectivity that is induced by the G-gel. Several aromatic compounds were separated in a solution containing GMP and potassium ion at different concentrations. The association constants were calculated by correlating the electrophoretic mobilities of the analytes obtained experimentally using a concentration of G-gel. During semi-quantitative estimation, naphthalene derivatives had larger association constants (K-ass = 10.3-16.8) compared with those of benzene derivatives (K-ass = 3.91-5.31), which means that the binding sites of G-gel match better to a naphthalene ring than to a benzene ring. A hydrophobic interaction was also found when the association constants for alkyl resorcinol were compared with those of different hydrocarbon chains. The association constants of nucleobases and tryptophan ranged from 6.05 to 12.6, which approximated the intermediate values between benzene and naphthalene derivatives. Consequently, the selective interaction between G-gel and aromatic compounds was classified as one of three types: (1) an intercalation into stacked planar GMP tetramers; (2) a hydrophobic interaction with a long alkyl chain; or, (3) a small contribution of steric hindrance and/or hydrogen bonding with functional groups such as amino and hydroxyl groups. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chroma.2013.02.090

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