189 results on '"Kiyoshi Toko"'
Search Results
2. Reusability Enhancement of Taste Sensor Using Lipid Polymer Membranes by Surfactant Cleaning Treatment
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Kiyoshi Toko, Yusuke Tahara, Hidekazu Ikezaki, Yapeng Yuan, Xiao Wu, and Masaaki Habara
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Taste ,Chemistry ,Hydrochloride ,010401 analytical chemistry ,Combined use ,Synthetic membrane ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Residue (chemistry) ,Adsorption ,Pulmonary surfactant ,Chemical engineering ,Electrical and Electronic Engineering ,Instrumentation ,Reusability - Abstract
The aim of our study was to enhance the reusability of a taste sensor by increasing the efficiency of the cleaning process. In this paper, we proposed a surfactant cleaning method for two types of bitterness sensor using lipid polymer membranes with high hydrophobicity. To select suitable surfactants for cleaning, the usability of four types of surfactant with different polarities and ionicities was evaluated. Among these surfactants, the anionic surfactant linear alkylbenzene sulfonate (LAS) showed no impact on the initial membrane potential and completely removed residue substances of high-concentration quinine hydrochloride adsorbed on the bitterness sensor used for hydrochloride salts. On the other hand, the amphoteric surfactant lauryl dimethylaminoacetic acid (LDA) showed no impact on the initial membrane potential and almost completely removed residue substances of high-concentration iso- $\alpha $ acid adsorbed on the bitterness sensor used for acidic bitter materials. Moreover, we found that the combined use of the conventional cleaning solution and LDA acid solution in turn greatly improved the reusability of an astringency sensor in multiple measurements of black tea.
- Published
- 2020
3. Taste Sensor: Electronic Tongue with Lipid Membranes
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Rui Yatabe, Yusuke Tahara, Xiao Wu, and Kiyoshi Toko
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Taste ,Chemistry ,Electronic tongue ,010401 analytical chemistry ,Biosensing Techniques ,02 engineering and technology ,Umami ,Sweetness ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Membrane Lipids ,Membrane ,Biomimetics ,Humans ,Gustatory system ,Electronic Nose ,0210 nano-technology ,Biological system - Abstract
Taste is of five basic types, namely, sourness, saltiness, sweetness, bitterness and umami. In this review, we focus on a potentiometric taste sensor that we developed and fabricated using lipid polymer membranes. The taste sensor can measure the taste perceived by humans and is called an electronic tongue with global selectivity, which is the property to discriminate taste qualities and quantify them without discriminating each chemical substance. This property is similar to the gustatory system; hence, the taste sensor is a type of biomimetic device. In this paper, we first explain the sensing mechanism of the taste sensor, its application to beer evaluation and the measurement mechanism. Second, results recently obtained are introduced; i.e., the application of the senor to high-potency sweeteners and the improvement of the bitterness sensor are explained. Last, quantification of the bitterness-masking effect of high-potency sweeteners is explained using a regression analysis based on both the outputs of bitterness and sweetness sensors. The taste sensor provides a biomimetic method different from conventional analytical methods.
- Published
- 2019
4. Potentiometric electronic tongue using lipid/polymer membrane
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Kiyoshi Toko, Hidekazu Ikezaki, Yusuke Tahara, and Masaaki Habara
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chemistry.chemical_classification ,Membrane ,Chemistry ,Electronic tongue ,Inorganic chemistry ,Potentiometric titration ,Polymer - Published
- 2021
5. Odor Recognition of Thermal Decomposition Products of Electric Cables Using Odor Sensing Arrays
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Hidekazu Takeda, Nobuyuki Fujiwara, Yuanchang Liu, Takeshi Onodera, Shintaro Furuno, Seiichi Uchida, Sosuke Akagawa, Kiyoshi Toko, and Rui Yatabe
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Thermogravimetric analysis ,safety devices ,artificial olfaction ,Materials science ,carbon black ,GC materials ,QD415-436 ,sensor array ,Biochemistry ,Analytical Chemistry ,law.invention ,chemistry.chemical_compound ,decomposition of electric cable ,Sensor array ,law ,odor discrimination ,Thermal ,Physical and Theoretical Chemistry ,Composite material ,Thermal decomposition ,Polyethylene ,odor sensor ,Polyvinyl chloride ,machine learning ,chemistry ,Odor ,chemical sensing ,Resistor - Abstract
An odor sensing system with chemosensitive resistors was used to identify the gases generated from overheated cables to prevent fire. Three different electric cables for a distribution cabinet were used. The cables had an insulation layer made of polyvinyl chloride (PVC) or cross-linked polyethylene (XLPE). The heat resistance of the cables was tested by differential thermal and thermogravimetric analyses. The thermal decomposition products of the cables were investigated by gas chromatography-mass spectrometry (GC-MS). For the odor sensing system, two types of 16-channel array were used to detect the generated gases. One contains high-polarity GC stationary phase materials and the other contains GC stationary phase materials of high to low polarity. The system could distinguish among three cable samples at 270 °C with an accuracy of about 75% through both arrays trained with machine learning. Furthermore, the system could achieve a recall rate of 90% and a precision rate of 70% when the abnormal temperature was set above the cables’ allowable conductor temperature at 130 °C. The odor sensing system could effectively detect the abnormal heating of the cables before the occurrence of fire. Therefore, it is helpful for fire prediction and detection systems in factories and substations.
- Published
- 2021
6. Detection of Catecholamine Metabolite in Urine Using Surface Plasmon Resonance Sensor
- Author
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Hideto Sonoda, Toshiro Matsui, Takuya Eda, Takeshi Onodera, and Kiyoshi Toko
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Chromatography ,Surface plasmon resonance sensor ,Chemistry ,Mechanical Engineering ,Catecholamine metabolite ,Urine ,Electrical and Electronic Engineering - Published
- 2019
7. Quantification of Pharmaceutical Bitterness Using a Membrane Electrode Based on a Hydrophobic Tetrakis [3,5-Bis (trifluoromethyl) phenyl] Borate
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Takeshi Shiino, Yusuke Tahara, Hidekazu Ikezaki, Kiyoshi Toko, and Xiao Wu
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tetrakis [3,5-bis (trifluoromethyl) phenyl] borate ,Hydrochloride ,surface charge density ,Synthetic membrane ,Ether ,02 engineering and technology ,01 natural sciences ,bitterness ,Analytical Chemistry ,lcsh:Biochemistry ,chemistry.chemical_compound ,lcsh:QD415-436 ,Physical and Theoretical Chemistry ,Phosphoric acid ,adsorption amount ,hydrophobicity ,Trifluoromethyl ,Chemistry ,010401 analytical chemistry ,Plasticizer ,021001 nanoscience & nanotechnology ,Combinatorial chemistry ,0104 chemical sciences ,Membrane ,Chemical stability ,0210 nano-technology ,fully dissociated - Abstract
Technologies for quantifying bitterness are essential for classifying medicines. As previously reported, taste sensors with lipid polymer membranes can respond to bitter hydrochloride substances in pharmaceuticals. However, the acid hydrolysis reaction between the lipid phosphoric acid di-n-decyl ester (PADE) and the plasticizer tributyl o-acetylcitrate (TDAB) led to a deterioration in sensor responses during storage. Given the cost of transportation and preservation for commercialization, membrane components that maintain physical and chemical stability during long-term storage are needed. Here we present a membrane electrode based on hydrophobic tetrakis [3,5-bis (trifluoromethyl) phenyl] borate (TFPB) and a plasticizer 2-nitrophenyl octyl ether (NPOE) for the quantification of pharmaceutical bitterness, they maintain a stable response before and after accelerated deterioration, as well as high selectivity and sensitivity. It is a first attempt to use a completely dissociative substance to replace non-completely dissociative lipids. Our work offsets the long-term stability issue of a bitterness sensor with a negatively charged hydrophobic membrane. Meanwhile, we provide the opportunity to select surface charge modifiers for a membrane surface using ester plasticizers containing oppositely charged impurities.
- Published
- 2021
8. Visualization of flavor of sake using taste sensor and gas chromatography‐mass spectrometry
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Miyo Hirata, Keiichi Mitani, Kiyoshi Toko, Yoichiro Kanno, Takeshi Onodera, and Shiho Shirota
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Taste ,Chromatography ,Computer Networks and Communications ,Chemistry ,Applied Mathematics ,Signal Processing ,General Physics and Astronomy ,Statistical analysis ,Electrical and Electronic Engineering ,Gas chromatography–mass spectrometry ,Flavor ,Visualization - Published
- 2020
9. Development of Taste Sensor to Detect Non-Charged Bitter Substances
- Author
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Masaaki Habara, Yusuke Tahara, Kiyoshi Toko, Hidekazu Ikezaki, Jumpei Yoshimatsu, Misaki Ishida, Takahiro Uchida, Honami Kojima, Miyako Yoshida, and Saeri Ikegami
- Subjects
Taste ,Carboxylic acid ,030303 biophysics ,Potentiometric titration ,Synthetic membrane ,Biosensing Techniques ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,bitterness ,Article ,Analytical Chemistry ,Membrane Potentials ,03 medical and health sciences ,chemistry.chemical_compound ,lipid/polymer membrane ,Caffeine ,medicine ,Humans ,Theophylline ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,Theobromine ,chemistry.chemical_classification ,0303 health sciences ,allostery ,010401 analytical chemistry ,bitterness sensor ,Combinatorial chemistry ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,non-charged substances ,Membrane ,chemistry ,taste sensor ,medicine.drug - Abstract
A taste sensor with lipid/polymer membranes is one of the devices that can evaluate taste objectively. However, the conventional taste sensor cannot measure non-charged bitter substances, such as caffeine contained in coffee, because the taste sensor uses the potentiometric measurement based mainly on change in surface electric charge density of the membrane. In this study, we aimed at the detection of typical non-charged bitter substances such as caffeine, theophylline and theobromine included in beverages and pharmaceutical products. The developed sensor is designed to detect the change in the membrane potential by using a kind of allosteric mechanism of breaking an intramolecular hydrogen bond between the carboxy group and hydroxy group of aromatic carboxylic acid (i.e., hydroxy-, dihydroxy-, and trihydroxybenzoic acids) when non-charged bitter substances are bound to the hydroxy group. As a result of surface modification by immersing the sensor electrode in a modification solution in which 2,6-dihydroxybenzoic acid was dissolved, it was confirmed that the sensor response increased with the concentration of caffeine as well as allied substances. The threshold and increase tendency were consistent with those of human senses. The detection mechanism is discussed by taking into account intramolecular and intermolecular hydrogen bonds, which cause allostery. These findings suggest that it is possible to evaluate bitterness caused by non-charged bitter substances objectively by using the taste sensor with allosteric mechanism.
- Published
- 2020
10. Identification of characteristic compounds of moderate volatility in breast cancer cell lines
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Yoshihiko Maehara, Yusuke Tahara, Keisuke Sanematsu, Toshiro Matsui, Eiji Oki, Takeshi Onodera, Kiyoshi Toko, Hideto Sonoda, Tomotsugu Rikitake, Kurebayashi Rintaro, Weilin Shen, Mitsuru Tanaka, Asuka Goda, Chung Hsuan, Masataka Oeki, and Yuzo Ninomiya
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Nonanal ,Cell Lines ,Biochemistry ,Mass Spectrometry ,Analytical Chemistry ,chemistry.chemical_compound ,Spectrum Analysis Techniques ,0302 clinical medicine ,Breast Tumors ,Tumor Cells, Cultured ,Medicine and Health Sciences ,Extraction Techniques ,0303 health sciences ,Multidisciplinary ,Fatty Acids ,Chromatographic Techniques ,Lipids ,Laboratory Equipment ,Chemistry ,Oncology ,030220 oncology & carcinogenesis ,Physical Sciences ,Engineering and Technology ,Medicine ,Female ,Biological Cultures ,Oxidation-Reduction ,Decenoic Acid ,Research Article ,Science ,Equipment ,Breast Neoplasms ,Research and Analysis Methods ,Gas Chromatography-Mass Spectrometry ,03 medical and health sciences ,Breast cancer ,Diagnostic Medicine ,Breast Cancer ,Cancer Detection and Diagnosis ,medicine ,Humans ,Solid-Phase Extraction ,Solid Phase Microextraction ,030304 developmental biology ,Volatile Organic Compounds ,Chromatography ,Cancers and Neoplasms ,Biology and Life Sciences ,Cancer ,Cell Cultures ,Decanal ,medicine.disease ,Culture Media ,Heptanal ,Octanal ,chemistry ,Cultured Fibroblasts ,Gas chromatography–mass spectrometry - Abstract
In this study, we were challenging to identify characteristic compounds in breast cancer cell lines. GC analysis of extracts from the culture media of breast cancer cell lines (MCF-7, SK-BR-3, and YMB-1) using a solid-phase Porapak Q extraction revealed that two compounds of moderate volatility, 1-hexadecanol and 5-(Z)-dodecenoic acid, were detected with markedly higher amount than those in the medium of fibroblast cell line (KMST-6). Furthermore, LC-TOF/MS analysis of the extracts clarified that in addition to the above two fatty acids, the amounts of five unsaturated fatty acids [decenoic acid (C10:1), decadienoic acid (C10:2), 5-(Z)-dodecenoic acid (C12:1), 5-(Z)-tetradecenoic acid (C14:1), and tetradecadienoic acid (C14:2)] in MCF-7 medium were higher than those in medium of KMST-6. Interestingly, H2O2-oxidation of 5-(Z)-dodecenoic acid and 5-(Z)-tetradecenoic acid produced volatile aldehydes that were reported as specific volatiles in breath from various cancer patients, such as heptanal, octanal, nonanal, decanal, 2-(E)-nonenal, and 2-(E)-octenal. Thus, we concluded that these identified compounds over-produced in breast cancer cells in this study could serve as potential precursors producing reported cancer-specific volatiles.
- Published
- 2020
11. Effects of Manufacturing Processing Conditions on Retronasal-Aroma Odorants from a Milk Coffee Drink
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Yuta Hirano, Michio Ikeda, Yasunori Sugawara, Hisakatsu Iwabuchi, Kazuhiro Miyaji, Yuriko Imayoshi, Takeshi Onodera, Masayuki Akiyama, and Kiyoshi Toko
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Coffee Flavor ,biology ,Chemistry ,010401 analytical chemistry ,Flavour ,food and beverages ,04 agricultural and veterinary sciences ,Sterilization (microbiology) ,biology.organism_classification ,040401 food science ,01 natural sciences ,0104 chemical sciences ,0404 agricultural biotechnology ,Milk products ,Odor ,Food science ,Aroma ,Food Science - Abstract
To develop a ready-to-drink (RTD) milk coffee that retains the original coffee flavor, the effects of manufacturing processing conditions on retronasal-aroma (RA) odorants were investigated by gas chromatography-olfactometry (CharmAnalysis™) using an RA simulator (RAS). Twenty-nine of 33 odorants detected in the RAS effluent (RAS odorants) were identified. The detected odorants were classified into 19 odor-description groups. The total odor intensity (charm value, CMV) of all coffee RAS odorants decreased approximately 68% following pH adjustment, whereas the total CMV increased 6% to 7% following ultra-high-temperature sterilization. The total CMV ratio (about 83%) of the milk coffee produced using a new blending-after-sterilization (BAS) process without pH adjustment of the coffee was greater than that (approximately 56%) prepared using a conventional blending-before-sterilization (BBS) process with pH adjustment. In BAS-processed milk coffees, the total CMV ratio (91%) with infusion (INF)-sterilized reconstituted milk (r-milk) was greater than that (83%) of plate (PLT)-sterilized r-milk. Principal component analysis of odor-description CMVs indicated that the effect of coffee pH adjustment on odor characteristics was greater than that of sterilization, that BAS and BBS samples differed, and that BAS milk coffee prepared using INF sterilization was more similar to homemade milk coffee (blending unsterilized coffee without pH adjustment with PLT-sterilized milk) than milk coffee prepared using PLT sterilization. In conclusion, the BAS process using INF sterilization is superior for manufacturing RTD milk coffee that retains odor characteristics similar to targeted homemade milk coffee. PRACTICAL APPLICATION: Ready-to-drink milk coffee beverages produced using conventional blending-before-sterilization methods do not retain their original coffee flavor following adjustment of the pH of the coffee during manufacturing. The use of newly developed blending-after-sterilization methods, by contrast, produces ready-to-drink milk coffee with an aroma more similar to that of homemade milk coffee, as demonstrated using an analytical system for characterizing food product aromas. The blending-after-sterilization process is now being used in Japan to produce ready-to-drink milk coffee beverages.
- Published
- 2018
12. A Quantitative Method for Acesulfame K Using the Taste Sensor
- Author
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Yuanchang Liu, Yusuke Tahara, Xiao Wu, Kiyoshi Toko, and Hidekazu Ikezaki
- Subjects
Taste ,high-potency sweeteners ,acesulfame K ,030303 biophysics ,Analytical chemistry ,Acesulfame potassium ,sweetness sensor ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,Analysis method ,0303 health sciences ,010401 analytical chemistry ,food and beverages ,lipid polymer membrane ,Sweetness ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,chemistry ,taste sensor ,Nonlinear regression - Abstract
We have developed a method to quantify the sweetness of negatively charged high-potency sweeteners coexisting with other taste substances. This kind of sweetness sensor uses lipid polymer membranes as the taste-sensing part. Two types of outputs have been defined in the measurement of the taste sensor: one is the relative value and the other is the CPA (the change in membrane potential caused by adsorption) value. The CPA value shows a good selectivity for high-potency sweeteners. On the other hand, the relative value is several times higher than the CPA value, but the relative value is influenced by salty substances. In order to obtain both high sensitivity and selectivity, we established a model for predicting the concentration of sweeteners with a nonlinear regression analysis method using the relative values of both the sweetness sensor and the saltiness sensor. The analysis results showed good correlations with the estimated concentration of acesulfame potassium coexisting with salty substances, as represented by R2 = 0.99. This model can correspond well to the prediction of acesulfame K in a concentration of 0.2&ndash, 0.7 mM, which is commonly used in food and beverages. The results obtained in this paper suggest that this method is useful for the evaluation of acesulfame K using the taste sensors.
- Published
- 2019
13. Highly Selective Rational Design of Peptide-Based Surface Plasmon Resonance Sensor for Direct Determination of 2,4,6-trinitrotoluene (TNT) Explosive
- Author
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Mina Okochi, Jin Wang, Masayoshi Tanaka, Rui Yatabe, Kiyoshi Toko, Takeshi Onodera, Masaki Muto, and Yusuke Tahara
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chemistry.chemical_classification ,Chemistry ,010401 analytical chemistry ,Metals and Alloys ,Rational design ,Peptide ,02 engineering and technology ,Complementarity determining region ,musculoskeletal system ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Combinatorial chemistry ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Materials Chemistry ,Trinitrotoluene ,Amine gas treating ,Electrical and Electronic Engineering ,Surface plasmon resonance ,0210 nano-technology ,Instrumentation ,Peptide sequence ,Conjugate - Abstract
In this study, 2,4,6-trinitrotoluene (TNT) binding peptide was synthesized and screened for TNT specific detection using surface plasmon resonance (SPR) sensor. The TNT binding peptide was rational design and synthesized through amino acid sequence from complementarity determining region (CDR) in the anti-TNT monoclonal antibody, which was produced from hybridoma cell using TNP-KLH conjugate as antigen. Three TNT binding peptide sequences were obtained from the heavy chain of CDR1 named TNTHCDR1, TNTHCDR2 from CDR2 and TNTHCDR3 from CDR3 of anti-TNT antibody. Screening process of three candidate peptides were carried out by using the SPR sensor with direct determination, which the peptide was directly immobilized on the sensor chip CM7 surface through amine coupling reaction. The results demonstrated that peptide TNTHCDR3 was determined as TNT binding peptide and no non-specific binding was observed. The selectivity of TNT binding peptide TNTHCDR3 was also testified by six kinds of TNT analogues. The results indicated the specific binding between TNT and peptide TNTHCDR3.
- Published
- 2018
14. Effects of Processing Conditions During Manufacture on Retronasal-Aroma Compounds from a Milk Coffee Drink
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Kono Masaya, Kazuhiro Miyazi, Masayuki Akiyama, Yuta Hirano, Takeshi Onodera, Michio Ikeda, Yuriko Imayoshi, Hisakatsu Iwabuchi, and Kiyoshi Toko
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0106 biological sciences ,Coffee Flavor ,biology ,Chemistry ,Manufacturing process ,education ,Flavour ,Sterilized milk ,food and beverages ,04 agricultural and veterinary sciences ,Sterilization (microbiology) ,biology.organism_classification ,040401 food science ,01 natural sciences ,0404 agricultural biotechnology ,Milk products ,010608 biotechnology ,Food science ,Effluent ,Aroma ,Food Science - Abstract
To develop a ready‐to‐drink (RTD) milk coffee retaining the original coffee flavor, the effects of processing conditions during manufacture on retronasal‐arma (RA) compounds from the milk coffee were investigated by gas chromatography‐mass spectrometry using an RA simulator (RAS). Thirteen of 46 detected compounds in the RAS effluent (RAS compounds) decreased significantly following pH adjustment of coffee (from pH 5.1 to 6.8) and 5 compounds increased. RAS compounds from coffee tended to decrease through the pH adjustment and subsequent sterilization. Significantly higher amounts of 13 RAS compounds were released from the milk coffee produced using a blending‐after‐sterilization (BAS) process without the pH adjustment than from that using a blending‐before‐sterilization (BBS) process with the pH adjustment. In BAS‐processed milk coffee, significantly lower amounts of 8 high‐volatility compounds and 1H‐pyrrole were released from coffee containing infusion‐sterilized (INF) milk than from coffee containing plate‐sterilized (PLT) milk, whereas 3 low‐volatility compounds were released significantly more from coffee using PLT milk. Principal component analysis revealed that the effect of the manufacturing process (BAS, BBS, or homemade (blending unsterilized coffee without pH adjustment with sterilized milk)) on milk coffee volatiles was larger than that of the sterilization method (INF or PLT) for milk, and that the sterilization method could result in different RAS volatile characteristics in BAS and homemade processes. In conclusion, a BAS process was found to be superior to a BBS process for the manufacture of an RTD milk coffee that retains volatile characteristics similar to that of a homemade milk coffee. Ready‐to‐drink (RTD) milk coffee manufactured using the conventional blending‐before‐sterilization process does not retain its original coffee flavor due to pH adjustment of the coffee during the process. The new blending‐after‐sterilization (BAS) process enabled the production of RTD milk coffee whose volatiles are closer to that of homemade milk coffee, as demonstrated by the results of RAS‐GC‐MS analysis. The BAS process has already been applied to the manufacture of RTD milk coffees in Japan.
- Published
- 2018
15. Quantitative prediction of bitterness masking effect of high-potency sweeteners using taste sensor
- Author
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Yusuke Tahara, Tamami Haraguchi, Hidekazu Ikezaki, Miyako Yoshida, Rui Yatabe, Xiao Wu, Hideya Onitake, Takahiro Uchida, and Kiyoshi Toko
- Subjects
Masking (art) ,Taste ,Aspartame ,Chemistry ,digestive, oral, and skin physiology ,010401 analytical chemistry ,Metals and Alloys ,food and beverages ,02 engineering and technology ,Sweetness ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Quinine Hydrochloride ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,stomatognathic system ,Materials Chemistry ,Food science ,Electrical and Electronic Engineering ,0210 nano-technology ,Instrumentation ,psychological phenomena and processes - Abstract
A taste sensor based on lipid/polymer membranes has been reported being possible to detect the masking of bitter substances or masking on bitterness receptors (physical masking or biochemical masking). However, it was difficult to express the bitterness suppression by sweeteners, which is decided by the balance of substances produced in human’s brain (functional masking). High-potency sweeteners are one of the sweeteners used for bitterness-masking in food and pharmaceutical industry. The objective of this study is to evaluate the bitterness-masking effect of high-potency sweeteners using the taste sensor. A bitterness sensor was used to evaluate the bitterness of quinine hydrochloride, and sweetness sensors for high-potency sweeteners were used to evaluate the sweetness of aspartame and saccharine sodium. The sensory evaluation was also carried out to examine the bitterness suppression effect of high-potency sweeteners. The bitterness-prediction formulas were proposed with the aid of a model regression analysis using two outputs from the bitterness sensor and the sweetness sensor for high-potency sweeteners. As a result, the predicted bitterness showed a good correlation with the human taste when aspartame or saccharine sodium was added to quinine hydrochloride. Thus, this study provided an effective method to evaluate the bitterness suppressed by high-potency sweeteners.
- Published
- 2016
16. Surfactant cleaning of lipid polymer membranes of bitterness sensor
- Author
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Hidekazu Ikezaki, Yapeng Yuan, Xiao Wu, Rui Yatabe, Kiyoshi Toko, and Yusuke Tahara
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Cleaning agent ,chemistry.chemical_classification ,High concentration ,Chemistry ,Synthetic membrane ,food and beverages ,Polymer ,Linear alkylbenzene sulfonate ,Membrane ,stomatognathic system ,Pulmonary surfactant ,Chemical engineering ,Selectivity ,psychological phenomena and processes - Abstract
The bitterness sensor with negatively charged lipid polymer membrane has been reported to perform high sensitivity and selectivity to bitterness of medicines. However, the conventional cleaning solution cannot completely remove residual substances after measuring high concentration bitter samples. Surfactant is an important cleaning agent used for membrane materials. This paper reported the effects of four kinds of surfactants in cleaning the lipid polymer membrane of the bitterness sensor. Among these surfactants, anionic surfactant linear alkylbenzene sulfonate (LAS) showed no detectable impact on membrane integrity and a good cleaning effect for the bitterness sensor.
- Published
- 2019
17. An SPR Sensor Chip Based on Peptide-Modified Single-Walled Carbon Nanotubes with Enhanced Sensitivity and Selectivity in the Detection of 2,4,6-Trinitrotoluene Explosives
- Author
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Jin Wang, Takeshi Onodera, Mina Okochi, Kiyoshi Toko, Sanyang Du, Rui Yatabe, and Masayoshi Tanaka
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π-stacking ,Materials science ,SPR ,Peptide ,02 engineering and technology ,Carbon nanotube ,010402 general chemistry ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,law.invention ,Matrix (chemical analysis) ,law ,SWCNTs ,Trinitrotoluene ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Surface plasmon resonance ,Instrumentation ,TNT analogues ,TNTHCDR3 ,Detection limit ,chemistry.chemical_classification ,021001 nanoscience & nanotechnology ,Chip ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Chemical engineering ,chemistry ,0210 nano-technology ,Selectivity - Abstract
In this study, we developed a surface plasmon resonance (SPR) sensor chip based on 2,4,6-trinitrotoluene (TNT) recognition peptide-modified single-walled carbon nanotubes (SWCNTs). The carboxylic acid-functionalized SWCNTs were immobilized on a 3-aminopropyltriethoxysilane (APTES)-modified SPR Au chip surface. Through &pi, stacking between the aromatic amino acids and SWCNTs, the TNT recognition peptide TNTHCDR3 was immobilized onto the surface of the SWCNTs. The peptide&ndash, SWCNTs-modified sensor surface was confirmed and evaluated by atomic force microscope (AFM) observation. The peptide&ndash, SWCNTs hybrid SPR sensor chip exhibited enhanced sensitivity with a limit of detection (LOD) of 772 ppb and highly selective detection compared with commercialized carboxymethylated dextran matrix sensor chips.
- Published
- 2018
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18. Bitterness compounds in coffee brew measured by analytical instruments and taste sensing system
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Misako Kakiuchi, Kazunari Miyake, Kazuya Iwai, Hidekazu Ikezaki, Yusuke Tahara, Tsukasa Kobayashi, Yusaku Narita, Shingo Ariki, Xiao Wu, Taku Hanzawa, Hirofumi Fujimoto, Taiji Fukunaga, and Kiyoshi Toko
- Subjects
Taste ,Nicotinamide ,Chemistry ,010401 analytical chemistry ,technology, industry, and agriculture ,food and beverages ,04 agricultural and veterinary sciences ,General Medicine ,Coffee ,040401 food science ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,chemistry.chemical_compound ,0404 agricultural biotechnology ,stomatognathic system ,Multivariate Analysis ,Food science ,Latent structure ,Sensing system ,Food Analysis ,Food Science - Abstract
We investigated the bitter compounds in coffee brews using multivariate analysis of the data obtained from analytical instrument and electronic taste sensor experiments. Coffee brews were prepared from coffee beans roasted to four different degrees. Each brew was fractionated into four fractions by liquid-liquid extraction. The relative amounts of 30 compounds in each fraction were analyzed by analytical instruments, and the bitterness response value of each fraction was analyzed by a taste sensor. Candidate bitter compounds in the coffee brews were identified with reference to their variable importance in projection and by coefficient of projection to latent structure regression (PLS-R) analysis. PLS-R analysis suggested that nicotinic acid, l-lactic acid, and nicotinamide contributed to the bitterness of the coffee brews. In fact, the coffee brews with added nicotinic acid, l-lactic acid, and nicotinamide had an increased bitterness response value compared to those without.
- Published
- 2021
19. Detection of Capsaicinoids in Capsicum Fruit Using Surface Plasmon Resonance Immunosensor
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Shengxi Tian, Takeshi Onodera, Rui Yatabe, and Kiyoshi Toko
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business.industry ,Chemistry ,Mechanical Engineering ,010401 analytical chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,Surface plasmon resonance ,010402 general chemistry ,business ,01 natural sciences ,0104 chemical sciences - Published
- 2016
20. Taste and Odor Sensors
- Author
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Kiyoshi Toko
- Subjects
Taste ,Odor ,Chemistry ,Food science - Published
- 2016
21. A bioinspired peptide matrix for the detection of 2,4,6-trinitrotoluene (TNT)
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Kiyoshi Toko, Takumi Komikawa, Kevin Critchley, Mina Okochi, Takeshi Onodera, Kentaro Yanai, Benjamin R. G. Johnson, Masayoshi Tanaka, and Stephen D. Evans
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Surface Properties ,Aptamer ,Biomedical Engineering ,Biophysics ,Peptide ,02 engineering and technology ,Binding, Competitive ,01 natural sciences ,Matrix (chemical analysis) ,Molecular recognition ,Explosive Agents ,Limit of Detection ,Electrochemistry ,Explosive detection ,Molecule ,Amino Acid Sequence ,Cysteine ,Disulfides ,Surface plasmon resonance ,Solid-Phase Synthesis Techniques ,chemistry.chemical_classification ,Molecular Structure ,Chemistry ,010401 analytical chemistry ,Antibodies, Monoclonal ,Equipment Design ,General Medicine ,Surface Plasmon Resonance ,021001 nanoscience & nanotechnology ,Combinatorial chemistry ,0104 chemical sciences ,Thermodynamics ,ATP-Binding Cassette Transporters ,Paratope ,Peptides ,0210 nano-technology ,Aptamers, Peptide ,Trinitrotoluene ,Biotechnology - Abstract
A novel peptide-based three-dimensional probe called “peptide matrix,” inspired by the antibody paratope region, was fabricated on a surface plasmon resonance (SPR) sensor chip to enhance the sensitivity of detecting the explosive 2,4,6-trinitrotoluene (TNT). Although peptide aptamer is an attractive candidate for a molecular recognition probe because of its ease of synthesis and chemical stability, it still has difficulty in applying to highly sensitive (i.e. parts-per-billion (ppb) or sub-ppb level) detections. Thus, we developed the concept of peptide matrix structure, which is constructed by consecutive disulfide bond formation between a large number of peptide fragments. This robust three-dimensional structure displays multiple binding sites which can efficiently associate with each TNT molecule. The peptide matrix lowered the dissociation constant (KD) by two orders of magnitude compared to the linear peptide aptamer, estimating KD as 10.1 nM, which is the lowest concentration reported by using peptide-based TNT probe. Furthermore, the concentration limit of detection of peptide matrix modified SPR sensor was 0.62 ppb, and hence comparable to single-chain variable fragment (scFv)-based TNT sensors. To our knowledge, this is the first report demonstrating peptide matrix fabrication and its application for small explosive molecule detection. This peptide matrix-based approach, which has the advantage of simple synthesis and high sensitivity, will be applicable to many other small-molecule label-free detections.
- Published
- 2020
22. Quantification of bitterness of coffee in the presence of high-potency sweeteners using taste sensors
- Author
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Xiao Wu, Yusuke Tahara, Taiji Fukunaga, Shingo Ariki, Kazuya Iwai, Kazunari Miyake, Hirofumi Fujimoto, Taku Hanzawa, Hidekazu Ikezaki, Yusaku Narita, Misako Kakiuchi, Kiyoshi Toko, and Tsukasa Kobayashi
- Subjects
Taste ,Metals and Alloys ,Acesulfame potassium ,food and beverages ,02 engineering and technology ,Sweetness ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,stomatognathic system ,chemistry ,Materials Chemistry ,Potency ,Food science ,Electrical and Electronic Engineering ,0210 nano-technology ,Instrumentation ,psychological phenomena and processes ,Roasting - Abstract
Electronic tongues have been identified as useful tools for quantifying the taste of food and beverages. However, the bitterness evaluation of coffee in the presence of high-potency sweeteners has not been performed yet. In this study, we investigated an approach to quantify the bitterness of coffee with different roasting degrees and the sweetness of acesulfame potassium (Ace K) added to the coffee using taste sensors with lipid polymer membranes. A formula for predicting coffee bitterness with the addition of Ace K was proposed using the responses of a bitterness sensor and a sweetness sensor. We found that the predicted coffee bitterness showed a good correlation with human taste.
- Published
- 2020
23. Development of a Sensor with a Lipid/Polymer Membrane Comprising Na+ Ionophores to Evaluate the Saltiness Enhancement Effect
- Author
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Hiroyuki Sano, Kiyoshi Toko, Xiao Wu, Yusuke Tahara, Hidekazu Ikezaki, Futa Nakatani, Tomofumi Ienaga, Yuki Muto, and Yuya Kaneda
- Subjects
saltiness sensor ,Taste ,Sodium ,Synthetic membrane ,Ionophore ,chemistry.chemical_element ,Salt (chemistry) ,02 engineering and technology ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,chemistry.chemical_compound ,lipid/polymer membrane ,Electrical and Electronic Engineering ,Instrumentation ,ionophore ,chemistry.chemical_classification ,Chromatography ,Chemistry ,saltiness enhancement effect ,010401 analytical chemistry ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Membrane ,Tartaric acid ,taste sensor ,0210 nano-technology ,Citric acid - Abstract
The saltiness enhancement effect is the effect whereby saltiness is enhanced by adding specific substances to salt (sodium chloride). Since this effect can be used in the development of salt-reduced foods, a method to objectively evaluate the saltiness with this effect is required. A taste sensor with lipid/polymer membranes has been used to quantify the taste of food and beverages in recent years. The sensor electrodes of this taste sensor have the feature of selectively responding to each of the five basic tastes, which is realized by the lipid/polymer membranes. In this study, we developed a new saltiness sensor based on the lipid/polymer membrane with the aim of quantifying the saltiness enhancement effect. In addition to the conventional components of a lipid, plasticizer, and polymer supporting reagent, the membrane we developed comprises ionophores, which selectively capture sodium ions. As a result, the response of the sensor increased logarithmically with the activity of NaCl in measured samples, similarly to the taste response of humans. In addition, all of the sensor responses increased upon adding saltiness-enhancing substances, such as citric acid, tartaric acid and branched-chain amino acids (BCAAs), to NaCl samples. These findings suggest that it is possible to quantify the saltiness enhancement effect using a taste sensor with lipid/polymer membranes.
- Published
- 2019
24. Laser-induced damage threshold test for interfacial analysis of lipid polymer membrane
- Author
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Kiyoshi Toko, Yusuke Tahara, Masatoshi Kozaki, Satoshi Ikezawa, and Rui Yatabe
- Subjects
chemistry.chemical_classification ,Materials science ,Threshold test ,010401 analytical chemistry ,Synthetic membrane ,020206 networking & telecommunications ,02 engineering and technology ,Polymer ,Laser ,Polarization (waves) ,01 natural sciences ,0104 chemical sciences ,law.invention ,Membrane ,chemistry ,Chemical engineering ,law ,0202 electrical engineering, electronic engineering, information engineering ,Molecule ,Spectroscopy - Abstract
This paper describes a preliminary test for sum-frequency generation (SFG) spectroscopy analysis of lipid polymer membranes. The SFG technique is used to analyze surface and structural information of molecules at gas-solid, gas-liquid, liquid-solid interfaces. A specially designed SFG system, which allows to analyze orientational polarization of polymer molecules at interfaces between a lipid polymer membrane and liquid/gas/solid, is being developed in our laboratory. A laser-induced damage threshold test of lipid polymer membranes was conducted in an early stage of this work.
- Published
- 2017
25. Improved Durability and Sensitivity of Bitterness-Sensing Membrane for Medicines
- Author
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Kiyoshi Toko, Takeshi Shiino, Yusuke Tahara, Rui Yatabe, Xiao Wu, Hideya Onitake, Hidekazu Ikezaki, and Zhiqin Huang
- Subjects
Polymers ,quinine hydrochloride ,02 engineering and technology ,lcsh:Chemical technology ,taste sensor ,bitterness sensor ,response deterioration ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,Membrane Potentials ,Contact angle ,chemistry.chemical_compound ,Hydrolysis ,Adsorption ,Adipate ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,Phosphoric acid ,chemistry.chemical_classification ,Chromatography ,Chemistry ,010401 analytical chemistry ,Plasticizer ,Polymer ,021001 nanoscience & nanotechnology ,Lipids ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Membrane ,Chemical engineering ,Taste ,0210 nano-technology - Abstract
This paper reports the improvement of a bitterness sensor based on a lipid polymer membrane consisting of phosphoric acid di-n-decyl ester (PADE) as a lipid and bis(1-butylpentyl) adipate (BBPA) and tributyl o-acetylcitrate (TBAC) as plasticizers. Although the commercialized bitterness sensor (BT0) has high sensitivity and selectivity to the bitterness of medicines, the sensor response gradually decreases to almost zero after two years at room temperature and humidity in a laboratory. To reveal the reason for the deterioration of the response, we investigated sensor membranes by measuring the membrane potential, contact angle, and adsorption amount, as well as by performing gas chromatography-mass spectrometry (GC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS). We found that the change in the surface charge density caused by the hydrolysis of TBAC led to the deterioration of the response. The acidic environment generated by PADE promoted TBAC hydrolysis. Finally, we succeeded in fabricating a new membrane for sensing the bitterness of medicines with higher durability and sensitivity by adjusting the proportions of the lipid and plasticizers.
- Published
- 2017
- Full Text
- View/download PDF
26. From Idea Generation to Development of Taste Sensor
- Author
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Kiyoshi Toko
- Subjects
Cognitive science ,Taste ,Chemistry ,Mechanical Engineering ,Electrical and Electronic Engineering ,Ideation - Published
- 2015
27. Array-Based Rational Design of Short Peptide Probe-Derived from an Anti-TNT Monoclonal Antibody
- Author
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Hiroshi Ueda, Kentaro Yanai, Kiyoshi Toko, Jin Wang, Takeshi Onodera, Mina Okochi, Masaki Muto, and Masayoshi Tanaka
- Subjects
medicine.drug_class ,Peptide ,02 engineering and technology ,Complementarity determining region ,Monoclonal antibody ,Sensitivity and Specificity ,01 natural sciences ,medicine ,Humans ,Amino Acid Sequence ,Immunoassay ,chemistry.chemical_classification ,Binding Sites ,biology ,Chemistry ,010401 analytical chemistry ,Antibodies, Monoclonal ,General Chemistry ,General Medicine ,Surface Plasmon Resonance ,musculoskeletal system ,021001 nanoscience & nanotechnology ,Complementarity Determining Regions ,0104 chemical sciences ,Amino acid ,Dissociation constant ,Biochemistry ,Docking (molecular) ,biology.protein ,Isoleucine ,Antibody ,Peptides ,0210 nano-technology ,Protein Binding ,Trinitrotoluene - Abstract
Complementarity-determining regions (CDRs) are sites on the variable chains of antibodies responsible for binding to specific antigens. In this study, a short peptide probe for recognition of 2,4,6-trinitrotoluene (TNT), was identified by testing sequences derived from the CDRs of an anti-TNT monoclonal antibody. The major TNT-binding site in this antibody was identified in the heavy chain CDR3 by antigen docking simulation and confirmed by an immunoassay using a spot-synthesis based peptide array comprising amino acid sequences of six CDRs in the variable region. A peptide derived from heavy chain CDR3 (RGYSSFIYWF) bound to TNT with a dissociation constant of 1.3 μM measured by surface plasmon resonance. Substitution of selected amino acids with basic residues increased TNT binding while substitution with acidic amino acids decreased affinity, an isoleucine to arginine change showed the greatest improvement of 1.8-fold. The ability to create simple peptide binders of volatile organic compounds from sequence information provided by the immune system in the creation of an immune response will be beneficial for sensor developments in the future.
- Published
- 2017
28. Rational Design of Peptide-Functionalized Surface Plasmon Resonance Sensor for Specific Detection of TNT Explosive
- Author
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Rui Yatabe, Jin Wang, Takeshi Onodera, Mina Okochi, Kiyoshi Toko, Masaki Muto, and Masayoshi Tanaka
- Subjects
Surface plasmon resonance sensor ,Explosive material ,Specific detection ,Peptide ,02 engineering and technology ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Surface plasmon resonance ,Instrumentation ,Peptide sequence ,TNT binding peptides ,chemistry.chemical_classification ,rationally designed ,Communication ,010401 analytical chemistry ,Rational design ,021001 nanoscience & nanotechnology ,musculoskeletal system ,Combinatorial chemistry ,APTES ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,amino acid sequence ,chemistry ,N-γ-maleimidobutyryl-oxysuccinimide ester ,0210 nano-technology ,Selectivity ,surface plasmon resonance - Abstract
In this study, a rationally-designed 2,4,6-trinitrotoluene (TNT) binding peptide derived from an amino acid sequence of the complementarity-determining region (CDR) of an anti-TNT monoclonal antibody was used for TNT detection based on a maleimide-functionalized surface plasmon resonance (SPR) sensor. By antigen-docking simulation and screening, the TNT binding candidate peptides were obtained as TNTHCDR1 derived from the heavy chain of CDR1, TNTHCDR2 derived from CDR2, and TNTHCDR3 from CDR3 of an anti-TNT antibody. The binding events between candidate peptides and TNT were evaluated using the SPR sensor by direct determination based on the 3-aminopropyltriethoxysilane (APTES) surface. The TNT binding peptide was directly immobilized on the maleimide-functionalized sensor chip surface from N-γ-maleimidobutyryl-oxysuccinimide ester (GMBS). The results demonstrated that peptide TNTHCDR3 was identified and selected as a TNT binding peptide among the other two candidate peptides. Five kinds of TNT analogues were also investigated to testify the selectivity of TNT binding peptide TNTHCDR3. Furthermore, the results indicated that the APTES-GMBS-based SPR sensor chip procedure featured a great potential application for the direct detection of TNT.
- Published
- 2017
29. Development of sweetness sensor for high-potency sweeteners using lipid polymer membrane
- Author
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Kiyoshi Toko, Xiao Wu, Yusuke Tahara, Masaaki Habara, Hidekazu Ikezaki, Tomohiro Hattori, and Rui Yatabe
- Subjects
chemistry.chemical_compound ,Taste ,Membrane ,Chromatography ,chemistry ,Sodium ,Potassium ,Plasticizer ,Acesulfame potassium ,Synthetic membrane ,chemistry.chemical_element ,Sweetness - Abstract
High-potency sweeteners are applied to low-calorie diets and bitterness-masking ingredients in pharmaceutical products. We have studied taste sensors with lipid polymer membranes based on potentiometric measurement system for high-potency sweeteners. However, the sensor also responds to astringency substances because of hydrophobic characteristics of the lipid polymer membrane. In this study, we developed a new taste sensor using a lipid polymer membrane for saccharin sodium and acesulfame potassium as negatively charged high-potency sweeteners. We optimized the quantities and types of lipids and plasticizers for the fabrication of the sensor with high selectivity and sensitivity. We succeeded in the fabrication of the new sensor, the output of which could be suppressed under −5 mV for astringency substances. Moreover, the sensor has a good sensitivity and selectivity for saccharin sodium and acesulfame potassium.
- Published
- 2017
30. Molecularly Imprinted Sol-Gel-Based QCM Sensor Arrays for the Detection and Recognition of Volatile Aldehydes
- Author
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Rui Yatabe, Kenshi Hayashi, Kiyoshi Toko, Bartosz Wyszynski, and Chuanjun Liu
- Subjects
Nonanal ,sensor array optimization ,Nonanoic acid ,02 engineering and technology ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Hexanal ,Aldehyde ,Article ,Analytical Chemistry ,Molecular Imprinting ,Matrix (chemical analysis) ,chemistry.chemical_compound ,aldehyde biomarker ,Organic chemistry ,lcsh:TP1-1185 ,molecularly imprinted sol-gel ,Electrical and Electronic Engineering ,Electrodes ,Instrumentation ,Sol-gel ,chemistry.chemical_classification ,Aldehydes ,Chromatography ,QCM sensor array ,Chemistry ,010401 analytical chemistry ,Quartz crystal microbalance ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Tetraethyl orthosilicate ,Quartz Crystal Microbalance Techniques ,0210 nano-technology ,Gels - Abstract
The detection and recognition of metabolically derived aldehydes, which have been identified as important products of oxidative stress and biomarkers of cancers; are considered as an effective approach for early cancer detection as well as health status monitoring. Quartz crystal microbalance (QCM) sensor arrays based on molecularly imprinted sol-gel (MISG) materials were developed in this work for highly sensitive detection and highly selective recognition of typical aldehyde vapors including hexanal (HAL); nonanal (NAL) and bezaldehyde (BAL). The MISGs were prepared by a sol-gel procedure using two matrix precursors: tetraethyl orthosilicate (TEOS) and tetrabutoxytitanium (TBOT). Aminopropyltriethoxysilane (APT); diethylaminopropyltrimethoxysilane (EAP) and trimethoxy-phenylsilane (TMP) were added as functional monomers to adjust the imprinting effect of the matrix. Hexanoic acid (HA); nonanoic acid (NA) and benzoic acid (BA) were used as psuedotemplates in view of their analogous structure to the target molecules as well as the strong hydrogen-bonding interaction with the matrix. Totally 13 types of MISGs with different components were prepared and coated on QCM electrodes by spin coating. Their sensing characters towards the three aldehyde vapors with different concentrations were investigated qualitatively. The results demonstrated that the response of individual sensors to each target strongly depended on the matrix precursors; functional monomers and template molecules. An optimization of the 13 MISG materials was carried out based on statistical analysis such as principle component analysis (PCA); multivariate analysis of covariance (MANCOVA) and hierarchical cluster analysis (HCA). The optimized sensor array consisting of five channels showed a high discrimination ability on the aldehyde vapors; which was confirmed by quantitative comparison with a randomly selected array. It was suggested that both the molecularly imprinting (MIP) effect and the matrix effect contributed to the sensitivity and selectivity of the optimized sensor array. The developed MISGs were expected to be promising materials for the detection and recognition of volatile aldehydes contained in exhaled breath or human body odor.
- Published
- 2017
- Full Text
- View/download PDF
31. Fabrication of taste sensor for education
- Author
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Yusuke Tahara, Xiao Wu, Kiyoshi Toko, and Hisao Kuriyaki
- Subjects
Taste ,Fabrication ,Taste quality ,Trioctylmethylammonium chloride ,Chemistry ,Science teaching ,Science class ,Teflon membrane ,Nanotechnology - Abstract
In order to solve the unconcern to usefulness of learning science among high school students in Japan, we developed a simple fabricated taste sensor with sensitivity and selectivity to each taste quality, which can be applied in science class. A commercialized Teflon membrane was used as the polymer membrane holding lipids. In addition, a non-adhesive method is considered to combine the membrane and the sensor electrode using a plastic cap which is easily accessible. The taste sensor for education fabricated in this way showed a good selectivity and sensitivity. By adjusting the composition of trioctylmethylammonium chloride (TOMA) and phosphoric acid di(2-ethylhexyl) ester (PAEE) included in lipid solution, we improved the selectivity of this simple taste sensor to saltiness and sourness. To verify this taste sensor as a useful science teaching material for science class, we applied this taste sensor into a science class for university students. By comparing the results between the sensory test and the s...
- Published
- 2017
32. Development of sweetness sensor with selectivity to negatively charged high-potency sweeteners
- Author
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Yusuke Tahara, Hirotaka Okazaki, Masato Yasuura, Hidekazu Ikezaki, and Kiyoshi Toko
- Subjects
Taste ,Chromatography ,Electronic tongue ,Sodium ,digestive, oral, and skin physiology ,Potentiometric titration ,Metals and Alloys ,Acesulfame potassium ,food and beverages ,chemistry.chemical_element ,Umami ,Sweetness ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Membrane ,chemistry ,Materials Chemistry ,Food science ,Electrical and Electronic Engineering ,Instrumentation - Abstract
Objective taste evaluation has been much in demand in the food, beverage and pharmaceutical industries. A taste-sensing system, which is an electronic tongue with “global selectivity,” is one of the methods used for objective taste evaluation. A taste sensor electrode responds to only one of the basic tastes (saltiness, sourness, sweetness, bitterness and umami) as a change in membrane potential caused by interactions with tastants. Sweet substances are compounds with diverse chemical structures and sizes. Since the taste-sensing system is a potentiometric measurement system using a change in membrane potential, three types of sweetness sensors are required, one for sweeteners with each type of electric charge (uncharged, positively charged and negatively charged). A sweetness sensor for uncharged sweeteners has been developed. Therefore, negatively charged sweeteners, such as saccharine sodium and acesulfame potassium, were chosen as the target substances in this study. We investigated the responses of various sensor membranes using a lipid and nine kinds of plasticizers to each basic taste sample. Furthermore, not only the selectivity of the membranes but also the concentration dependence of their response to sweeteners was investigated. As a result, one of the developed sensors showed responses of over 20 mV to 5 mM saccharine sodium and 10 mM acesulfame potassium in CPA value measurement (CPA: change in membrane potential caused by adsorption). On the other hand, the sensor also showed nearly zero responses to other basic taste samples. In addition, saltiness was the only interfering taste, and the responses to target substances in relative value measurement were over 140 mV. The developed sweetness sensor had high selectivity and concentration-dependent responses. Hence, we concluded that the sensor is suitable for use as a sweetness sensor for high-potency sweeteners with a negative electric charge.
- Published
- 2014
33. Towards an Electronic Dog Nose: Surface Plasmon Resonance Immunosensor for Security and Safety
- Author
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Takeshi Onodera and Kiyoshi Toko
- Subjects
Safety Management ,Materials science ,Explosive material ,education ,Nanotechnology ,Review ,Nose ,lcsh:Chemical technology ,Biochemistry ,Security Measures ,Analytical Chemistry ,chemistry.chemical_compound ,Hydrophilic polymers ,Dogs ,Explosive Agents ,Dendrimer ,antibody ,Monolayer ,electronic dog nose ,Animals ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Surface plasmon resonance ,security and safety ,Instrumentation ,immunosensor ,Immunoassay ,explosives ,Equipment Design ,Surface Plasmon Resonance ,Atomic and Molecular Physics, and Optics ,Equipment Failure Analysis ,Smell ,chemistry ,Ethylene glycol - Abstract
This review describes an “electronic dog nose” based on a surface plasmon resonance (SPR) sensor and an antigen–antibody interaction for security and safety. We have concentrated on developing appropriate sensor surfaces for the SPR sensor for practical use. The review covers different surface fabrications, which all include variations of a self-assembled monolayer containing oligo(ethylene glycol), dendrimer, and hydrophilic polymer. We have carried out detection of explosives using the sensor surfaces. For the SPR sensor to detect explosives, the vapor or particles of the target substances have to be dissolved in a liquid. Therefore, we also review the development of sampling processes for explosives, and a protocol for the measurement of explosives on the SPR sensor in the field. Additionally, sensing elements, which have the potential to be applied for the electronic dog nose, are described.
- Published
- 2014
34. Examination of Amount of Astringent Substances Adsorbed Onto Lipid/Polymer Membrane Used in Taste Sensor
- Author
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Daichi Hara, Yusuke Tahara, Takuro Fukagawa, Kiyoshi Toko, and Masato Yasuura
- Subjects
chemistry.chemical_classification ,Taste ,Membrane ,Adsorption ,Astringent ,chemistry ,Organic chemistry ,Polymer ,Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics - Published
- 2014
35. Development of a Sweetness Sensor for Aspartame, a Positively Charged High-Potency Sweetener
- Author
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Yusuke Tahara, Masato Yasuura, Hidekazu Ikezaki, and Kiyoshi Toko
- Subjects
Taste ,High selectivity ,Synthetic membrane ,Biosensing Techniques ,sweetness sensor ,lcsh:Chemical technology ,Biochemistry ,Article ,aspartame ,Analytical Chemistry ,Membrane Potentials ,taste sensor ,high-potency sweetener ,lipid/polymer membrane ,chemistry.chemical_compound ,Sensory tests ,Plasticizers ,Negative charge ,lcsh:TP1-1185 ,Food science ,Electrical and Electronic Engineering ,Instrumentation ,Electrodes ,Chromatography ,Aspartame ,Chemistry ,digestive, oral, and skin physiology ,food and beverages ,Esters ,Sweetness ,Lipids ,Atomic and Molecular Physics, and Optics ,Membrane ,Sweetening Agents ,Adsorption - Abstract
Taste evaluation technology has been developed by several methods, such as sensory tests, electronic tongues and a taste sensor based on lipid/polymer membranes. In particular, the taste sensor can individually quantify five basic tastes without multivariate analysis. However, it has proven difficult to develop a sweetness sensor, because sweeteners are classified into three types according to the electric charges in an aqueous solution; that is, no charge, negative charge and positive charge. Using membrane potential measurements, the taste-sensing system needs three types of sensor membrane for each electric charge type of sweetener. Since the commercially available sweetness sensor was only intended for uncharged sweeteners, a sweetness sensor for positively charged high-potency sweeteners such as aspartame was developed in this study. Using a lipid and plasticizers, we fabricated various lipid/polymer membranes for the sweetness sensor to identify the suitable components of the sensor membranes. As a result, one of the developed sensors showed responses of more than 20 mV to 10 mM aspartame and less than 5 mV to any other taste. The responses of the sensor depended on the concentration of aspartame. These results suggested that the developed sweetness sensor had high sensitivity to and high selectivity for aspartame.
- Published
- 2014
36. Taste and Other Sensors
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Chemistry ,Food science ,Electrical and Electronic Engineering - Published
- 2014
37. Taste sensor using strongly hydrophobic membranes to measure hydrophobic substances
- Author
-
Kiyoshi Toko, Yusuke Tahara, Rixin Wang, Rui Yatabe, Xiao Wu, and Ke Ji
- Subjects
Absorption (pharmacology) ,Taste ,Chromatography ,Chemistry ,Monosodium glutamate ,010401 analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Hydrophobe ,chemistry.chemical_compound ,Adsorption ,Membrane ,Pulmonary surfactant ,Sodium dodecyl sulfate ,0210 nano-technology - Abstract
A taste sensor using a lipid/polymer membrane, i.e., an electronic tongue with global selectivity, has been developed for objective evaluation of the taste of foods and beverages. Moreover, the taste sensor has been also contributing to safety of foods, e.g., the sensor membrane with strong hydrophobicity was used to detect sodium dodecyl sulfate (SDS), a negatively charged surfactant, which was generally added into the pesticide because of its strongly melting effect. An immersion process in monosodium glutamate (MSG) solution, called “MSG preconditioning” was needed to obtain the change in membrane electric potential caused by adsorption (CPA) for sensor membrane before measurement. However, what happened to sensor membrane during MSG preconditioning is unclear. In this paper, we examined the relationship between the CPA value and the period of MSG preconditioning. The amount of adsorbed SDS and MSG was measured to figure out whether the CPA value is related to the amount of adsorption. As a result, with the precondition process progressed, the CPA values showed concentration dependence on SDS concentration, and increased to a peak by preconditioning for one day then decreased to a stable state after that. The amount of adsorbed SDS depended on the SDS concentration but did not change with the increasing of preconditioning time. In conclusion, we revealed that the most suitable time of MSG preconditioning for the membrane for SDS was one day. The CPA value was affected by both the surface charge density and the amount of absorption.
- Published
- 2016
38. Peptide-modified Microelectrode-based Potentiometric Device for 2,4,6-trinitrotoluene Molecule Detection
- Author
-
Jin Wang, Rui Yatabe, Masayoshi Tanaka, Mina Okochi, Takeshi Onodera, and Kiyoshi Toko
- Subjects
chemistry.chemical_classification ,Microelectrode ,chemistry ,Potentiometric titration ,Molecule ,Trinitrotoluene ,General Materials Science ,Peptide ,Instrumentation ,Combinatorial chemistry - Published
- 2019
39. Prediction of Glycogen and Moisture Contents in Japanese Wagyu Beef by Fourier Transform Near-infrared Spectroscopy for Quality Evaluation
- Author
-
Zhifeng Yao, Kiyoshi Toko, Xiao Ye, Rui Yatabe, Toshiaki Oe, Ken Iwao, Yusuke Tahara, Masami Nishimura, Takeshi Onodera, and Naruhiko Tanaka
- Subjects
chemistry.chemical_compound ,symbols.namesake ,Quality (physics) ,Materials science ,Fourier transform ,Moisture ,Glycogen ,chemistry ,Near-infrared spectroscopy ,Analytical chemistry ,symbols ,General Materials Science ,Instrumentation - Published
- 2019
40. Sensitive Detection of Capsaicinoids Using a Surface Plasmon Resonance Sensor with Anti-Homovanillic Acid Polyclonal Antibodies
- Author
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Rui Yatabe, Takeshi Onodera, Kiyoshi Toko, and Shingo Nakamura
- Subjects
Detection limit ,immunosensor ,Vanillyl group ,Chromatography ,Immunogen ,biology ,Hydrochloride ,lcsh:Biotechnology ,Clinical Biochemistry ,capsaicinoids ,surface plasmon resonance ,homovanillic acid ,Analytical chemistry ,General Medicine ,Article ,Dihydrocapsaicin ,chemistry.chemical_compound ,chemistry ,Polyclonal antibodies ,lcsh:TP248.13-248.65 ,biology.protein ,Surface plasmon resonance ,Biosensor - Abstract
Recently, highly functional biosensors have been developed in preparation for possible large-scale terrorist attacks using chemical warfare agents. Practically applicable sensors are required to have various abilities, such as high portability and operability, the capability of performing rapid and continuous measurement, as well as high sensitivity and selectivity. We developed the detection method of capsaicinoids, the main component of some lachrymators, using a surface plasmon resonance (SPR) immunosensor as an on-site detection sensor. Homovanillic acid, which has a vanillyl group similar to capsaicinoids such as capsaicin and dihydrocapsaicin, was bound to Concholepas concholepas hemocyanin (CCH) for use as an immunogen to generate polyclonal antibodies. An indirect competitive assay was carried out to detect capsaicinoids using SPR sensor chips on which different capsaicin analogues were immobilized. For the sensor chip on which 4-hydroxy-3-methoxybenzylamine hydrochloride was immobilized, a detection limit of 150 ppb was achieved. We found that the incubation time was not required and the detection can be completed in five minutes.
- Published
- 2013
41. Fabrication of an SPR Sensor Surface with Antifouling Properties for Highly Sensitive Detection of 2,4,6-Trinitrotoluene Using Surface-Initiated Atom Transfer Polymerization
- Author
-
Takeshi Onodera, Rui Yatabe, and Kiyoshi Toko
- Subjects
Polymers ,Surface Properties ,Transducers ,Inorganic chemistry ,Analytical chemistry ,trinitrotoluene ,lcsh:Chemical technology ,Biochemistry ,Article ,Analytical Chemistry ,chemistry.chemical_compound ,Adsorption ,nonspecific adsorption ,Explosive Agents ,Monolayer ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Surface plasmon resonance ,Instrumentation ,Immunoassay ,chemistry.chemical_classification ,Detection limit ,immunosensor ,Self-assembled monolayer ,Equipment Design ,Polymer ,musculoskeletal system ,Atomic and Molecular Physics, and Optics ,Equipment Failure Analysis ,Monomer ,surface initiated atom transfer polymerization ,chemistry ,Polymerization ,self-assembled monolayer ,Equipment Contamination ,Terrorism ,surface plasmon resonance - Abstract
In this study, we modified a surface plasmon resonance immunosensor chip with a polymer using surface-initiated atom transfer polymerization (SI-ATRP) for the highly sensitive detection of 2,4,6-trinitrotoluene (TNT). To immobilize a TNT analogue on the polymer, mono-2-(methacryloyloxy)ethylsuccinate (MES), which has a carboxyl group, was used in this study. However, the anti-TNT antibody may adsorb non-specifically on the polymer surface by an electrostatic interaction because MES is negatively charged. Therefore, a mixed monomer with MES and diethylaminoethylmethacrylate (DEAEM), which has a tertiary amino group and is positively charged, was prepared to obtain electroneutrality for suppressing the nonspecific adsorption. The detection of TNT was performed by inhibition assay using the polymer surface. To ensure high sensitivity to TNT, the affinity between the surface and the antibody was optimized by controlling the density of the initiator for ATRP by mixing two types of self-assembled monolayer reagents. As a result, a limit of detection of 5.7 pg/mL (ppt) for TNT was achieved using the optimized surface.
- Published
- 2013
42. Quantification of tastes of amino acids using taste sensors
- Author
-
Yoshikazu Kobayashi, Yusuke Tahara, Masato Yasuura, Kiyoshi Toko, Hiroki Akitomi, and Hidekazu Ikezaki
- Subjects
chemistry.chemical_classification ,Taste ,Arginine ,Metals and Alloys ,food and beverages ,Sweetness ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Amino acid ,Simple linear regression analysis ,stomatognathic system ,chemistry ,Materials Chemistry ,Food science ,Electrical and Electronic Engineering ,Instrumentation ,psychological phenomena and processes - Abstract
In this study, we quantified the tastes of branched-chain amino acids (BCAAs) and demonstrated the bitterness suppression effect using taste sensors that can selectively evaluate two basic taste qualities. Bitterness and sweetness sensors with a lipid/polymer membrane were used to quantity bitterness and sweetness of amino acids, respectively. Simple linear regression analysis revealed that the response values obtained from the corresponding taste sensor (bitterness, sweetness) and the scores obtained in the sensory test showed a strong correlation, demonstrating that the intensity of bitterness and sweetness of amino acids can be estimated. Moreover, a significant decrease in the response value of the bitterness sensor was observed when l -arginine ( l -Arg) was added to bitter amino acids, indicating that the bitterness suppression effect perceivable by humans can be demonstrated.
- Published
- 2013
43. Taste Sensor
- Author
-
Yoshikazu Kobayashi, Yusuke Tahara, Masaaki Habara, Kiyoshi Toko, and Hidekazu Ikezaki
- Subjects
Communication ,Taste ,Chemistry ,business.industry ,Electronic tongue ,010401 analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,business ,Selectivity ,01 natural sciences ,0104 chemical sciences - Published
- 2016
44. Odor Recorder and Olfactory Display
- Author
-
Kiyoshi Toko
- Subjects
Odor ,Chemistry ,Neuroscience - Published
- 2016
45. Evaluation of Water Quality Using Taste Sensor
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Chemistry ,Water quality ,Food science - Published
- 2016
46. Evaluating the Reduced Hydrophobic Taste Sensor Response of Dipeptides by Theasinensin A by Using NMR and Quantum Mechanical Analyses
- Author
-
Yuji Miyata, Takashi Tanaka, Toshiro Matsui, Jian Guo, Yusuke Tahara, Kazunari Tanaka, Xiao Wu, Naoto Hirasaki, and Kiyoshi Toko
- Subjects
Models, Molecular ,Magnetic Resonance Spectroscopy ,Indoles ,Physiology ,Lipid Bilayers ,Analytical chemistry ,lcsh:Medicine ,Social Sciences ,Biosensing Techniques ,Spectrum analysis techniques ,01 natural sciences ,Physical Chemistry ,Catechin ,Diffusion ,Heterocyclic Compounds ,Medicine and Health Sciences ,Psychology ,lcsh:Science ,Membrane potential ,Multidisciplinary ,Chemistry ,Organic Compounds ,Physics ,Absorption Spectroscopy ,04 agricultural and veterinary sciences ,Nuclear magnetic resonance spectroscopy ,Dipeptides ,040401 food science ,Sensory Systems ,Partition coefficient ,Solutions ,Electrophysiology ,Membrane ,Taste ,Physical Sciences ,Thermodynamics ,Sensory Perception ,Protons ,Hydrophobic and Hydrophilic Interactions ,Protein Binding ,Research Article ,Surface Chemistry ,Absorption spectroscopy ,Membrane Potential ,0404 agricultural biotechnology ,NMR spectroscopy ,Phenols ,Humans ,Benzopyrans ,Spectroscopy ,Nuclear Physics ,Nucleons ,Chemical shift ,010401 analytical chemistry ,lcsh:R ,Organic Chemistry ,Chemical Compounds ,Resonance ,Biology and Life Sciences ,0104 chemical sciences ,Research and analysis methods ,Artificial Membranes ,Quantum Theory ,lcsh:Q ,Neuroscience - Abstract
The current study demonstrated that theasinensin A (TSA) had a potential to form the complex with hydrophobic Trp-containing dipeptides, and to reduce their membrane potential by artificial-lipid membrane taste sensor. At a 1:3 molar ratio of the 6 Trp-containing dipeptides together with TSA, we observed a significant chemical shift of the protons of the dipeptides (Δδ) to a high magnetic field, when analyzed using 1H-nuclear-magnetic resonance (NMR) spectroscopy. The Δδ values were correlated with the hydrophobicity (log P) of the dipeptides and significant correlations were obtained (P = 0.022, R2 = 0.77); e.g., Trp-Leu with the highest log P value of 1.623 among the tested dipeptides showed the highest Δδ value of 0.105 ppm for the H7 proton of Trp-Leu, while less chemical shifts were observed in theasinensin B and epigallocatechin-3-O-gallate. Diffusion-ordered NMR spectroscopy revealed that the diffusion coefficient of 3 mM of Trp-Leu (7.6 × 10−11 m2/s) at a pulse field gradient in the range 0.05–0.3 T/m decreased in the presence of 3 mM TSA (6.6 × 10−11 m2/s), suggesting that Trp-Leu forms a complex with TSA. Quantum mechanical calculations and rotating frame nuclear Overhauser effect-NMR spectroscopy provided configuration information on the geometry of the complex that Trp-Leu formed with TSA (1:1 complex) with a ΔG energy of –8.7 kJ/mol. A sensor analysis using artificial-lipid membranes demonstrated that the changes in membrane potential of 1 mM Trp-Leu (21.8 ± 1.3 mV) and Leu-Trp (5.3 ± 0.9 mV) were significantly (P < 0.001) reduced by 1 mM TSA (Trp-Leu, 13.1 ± 2.4 mV; Leu-Trp, 3.5 ± 0.5 mV; TSA alone, 0.2 ± 0.01 mV), indicating the effective suppression of hydrophobicity of dipeptides by TSA-formed complex.
- Published
- 2016
47. Development of Sensor Surfaces Using Poly-(N-vinylformamide) for Sensitive Detection of 2,4,6-Trinitrotoluene by Displacement Method on a Surface Plasmon Resonance Sensor
- Author
-
Ryosuke Ishii, Kiyoshi Toko, Rui Yatabe, and Takeshi Onodera
- Subjects
Detection limit ,biology ,010401 analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Matrix (chemical analysis) ,Hydrolysis ,chemistry.chemical_compound ,Acetic acid ,chemistry ,Succinic acid ,biology.protein ,General Materials Science ,Amine gas treating ,Surface plasmon resonance ,Bovine serum albumin ,0210 nano-technology ,Instrumentation ,Nuclear chemistry - Abstract
To detect 2,4,6-trinitrotoluene (TNT) using a displacement method over a surface plasmon resonance immunosensor, we developed sensor surfaces modified with a poly-(N-vinylformamideco-vinylamine), which was synthesized from a monomer, N-vinylformamide, and was hydrolyzed to produce amine groups, and TNT analogs. Poly-(N-vinylformamide-co-vinylamine) that reacted with succinic acid was used as a matrix of a sensor surface for increasing the number of antibody binding sites. 2,4-Dinitrophenyl glycine, 3-nitrophenyl acetic acid, and 4-nitrophenyl acetic acid were immobilized on the polymer-modified sensor surfaces. We evaluated the suppression ability of the sensor surface for nonspecific adsorption and determined the limit of detection (LOD) for TNT. As a result, a sensor chip suppressed nonspecific adsorption for 1 mg/mL bovine serum albumin and lysozyme. TNT was measured by the displacement method, and the LOD achieved over a 3-nitrophenyl acetic acid-modified sensor chip was 0.9 ng/mL (ppb).
- Published
- 2016
48. Beer Analysis Using an Electronic Tongue
- Author
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Kiyoshi Toko and Yusuke Tahara
- Subjects
Taste ,Tongue map ,Chemistry ,Electronic tongue ,food and beverages ,Gustatory system ,Food science - Abstract
A taste sensor is an electronic tongue with global selectivity, which means the characteristics to decompose a chemical substance into taste qualities and to quantify each of them. It comprises several kinds of electrodes, on which a lipid/polymer membrane is pasted, and can discriminate, identify, and quantify the taste of foods or medicines. It is now commercialized, and has been applied to many kinds of foods and medicines. The composition of the membrane is designed by considering the membrane electric charge density and the hydrophobicity on the basis of physicochemical properties of taste substances. The taste is evaluated using the linear transformation of sensor output, and it provides a “scale of taste.” The obtained taste pattern for beer is constructed from five axes of five basic taste qualities. A taste map expressed by 2 axes of bitterness and sourness is obtained for 40 brands of beer. These results enable us to discuss and compare taste characteristics of beer.
- Published
- 2016
49. Au nanoparticles decorated polyaniline nanofiber sensor for detecting volatile sulfur compounds in expired breath
- Author
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Kenshi Hayashi, Kiyoshi Toko, and Chuanjun Liu
- Subjects
Materials science ,Metals and Alloys ,chemistry.chemical_element ,Nanoparticle ,Nanotechnology ,Condensed Matter Physics ,Sulfur ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Breath gas analysis ,Nanosensor ,Colloidal gold ,Nanofiber ,Polyaniline ,Electrode ,Materials Chemistry ,Electrical and Electronic Engineering ,Instrumentation - Abstract
A chemiresistive sensor based on polyaniline (PANI) nanofibers decorated with highly dispersed gold nanoparticles (AuNPs) is developed to detect the volatile sulfur compounds (VSCs) of human expired breath. The PANI nanofibers with a characteristic of horizontal orientation on the insulating gap area of an interdigitated electrode are prepared by a temple-free electrochemical polymerization. The formation of the fine AuNPs on the PANI nanofibers is realized by the redox reaction between HAuCl 4 and PANI in the form of emeraldine. The PANI/AuNPs sensors exhibit good sensing responses to H 2 S and CH 3 SH gases. The sensing ability of the fabricated electrodes on VSCs contained in human breath is confirmed by their response upon exposure to the expired breath of a healthy volunteer after ingesting raw garlic. The developed nanosensors, together with a multichannel sensing system, are expected to be used in breath analysis and disease diagnose related to malodor biomarker gases.
- Published
- 2012
50. Detection of Furfural Using Surface Plasmon Resonance Sensor with Indirect Competitive Method
- Author
-
Rui Yatabe, Miaomiao Ma, Kiyoshi Toko, Takeshi Onodera, and Haoyu Luo
- Subjects
010309 optics ,chemistry.chemical_compound ,Surface plasmon resonance sensor ,Materials science ,chemistry ,Mechanical Engineering ,010401 analytical chemistry ,0103 physical sciences ,Analytical chemistry ,Electrical and Electronic Engineering ,Furfural ,01 natural sciences ,0104 chemical sciences - Published
- 2017
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