論文発表
Masato Saito, Natsuko Uchida, Shunsuke Furutani, Mizuho Murahashi, Wilfred Espulgar, Naoki Nagatani, Hidenori Nagai, Yuki Inoue, Tomohiko Ikeuchi, Satoshi Kondo, Hirotaka Uzawa, Yasuo Seto, Eiichi Tamiya, Field-deployable rapid multiple biosensing system for detection of chemical and biological warfare agents, Microsyst. Nanoeng., 4, 17083, 2018
The threat of biological and chemical terror acts remains a growing worldwide concern. There is therefore a need to develop appropriate technology for the detection of chemical and biological warfare agents, with early identification intended for use by first responders. Here, we disclose the developed autonomous air sampling and detection system for evaluation of the presence of chemical and biological warfare agents that can be harmful to the population. The current device utilizes the designed mist generator-assisted air collection system (338 l min−1) and biosensing chip technologies, such as electrochemical measurement, Au nanoparticle-based localized surface plasmon resonance, and rapid microfluidic chip PCR for detection of minute concentrations lower than the mean lethal dose (LD50) of nerve gases (sarin and VX), toxic proteins (BTX/A/Hc and ricin), and pathogens (anthrax simulant). An operation time of only 5–15 min is needed for the collection and detection; sample preparation is already integrated into the system without the need for direct human intervention. In addition to the system’s sensitivity and ease of use, its portability makes it highly beneficial for first responders, which could aid in immediate risk assessment and mitigation of on-site events.
Naoki Nagatani, Yuki Inoue, Akiko Araki, Hiromi Ushijima, Gen Hattori, Yasuhiro Sakurai, Yutaka Ogidou, Masato Saito, Eiichi Tamiya, Rapid sensing of antioxidant capacity based on electrochemiluminescence induced by electrochemically generated reactive oxygen species, Electrochimica Acta, 222, 580, 2016
A simple and rapid electrochemiluminescence (ECL) method for the measurement of antioxidant capacity using a portable ECL device with a screen-printed electrode is described. The ECL method is based on the luminous reaction of reactive oxygen species (ROS), luminol radicals and antioxidants. ROS are generated by the electrochemical reduction of dissolved oxygen and competitively react with the luminol and antioxidants. The ECL intensity depends on the antioxidant capacity because the radicals are neutralized by the antioxidants, suppressing the luminous reaction. An antioxidant standard curve was generated using different concentrations of known amounts of Trolox by ECL measurement and the detection limit for antioxidant capacity was found to be 0.06 mM of Trolox. An antioxidant capacity of beverages (22 types) was evaluated by comparing with the standard curve of Trolox. The time necessary for the ECL measurement of antioxidant capacity is only two minutes after combining the sample solution with luminol on a screen-printed electrode.
Daisuke Uesugi, Hiroki Hamada, Kei Shimoda, Naoji Kubota, Shin-ichi Ozaki, Naoki Nagatani, Synthesis, oxygen radical absorbance capacity, and tyrosinase inhibitory activity of glycosides of resveratrol, pterostilbene, and pinostilbene, Bioscience, Biotechnology, and Biochemistry, 81, 226, 2016
The stilbene compound resveratrol was glycosylated to give its 4′-O-β-D-glucoside as the major product in addition to its 3-O-β-D-glucoside by a plant glucosyltransferase from Phytolacca americana expressed in recombinant Escherichia coli. This enzyme transformed pterostilbene to its 4′-O-β-D-glucoside, and converted pinostilbene to its 4′-O-β-D-glucoside as a major product and its 3-O-β-D-glucoside as a minor product. An analysis of antioxidant capacity showed that the above stilbene glycosides had lower oxygen radical absorbance capacity (ORAC) values than those of the corresponding stilbene aglycones. The 3-O-β-D-glucoside of resveratrol showed the highest ORAC value among the stilbene glycosides tested, and pinostilbene had the highest value among the stilbene compounds. The tyrosinase inhibitory activities of the stilbene aglycones were improved by glycosylation; the stilbene glycosides had higher activities than the stilbene aglycones. Resveratrol 3-O-β-D-glucoside had the highest tyrosinase inhibitory activity among the stilbene compounds tested.
Ampornphan Siriviriyanun, Toyoko Imae, Naoki Nagatani, Electrochemical biosensors for bio contaminant detection consisting of carbon nanotubes, platinium nanoparticles, dendrimers, and enzymes, Analytical Biochemistry, 443,169, 2013
The presented approach provides the advanced development of effective, rapid, and versatile electrochemical sensors for a small amount of analytes on potential, cheap, and disposable printed chips. The electrocatalytic activity of this biosensor revealed the feasible detection of hydrogen peroxide at low potential (∼0.09 V) and the detection of a biocontaminant inhibitor (organophosphorus pesticide) in a wide range of concentrations. This efficiency comes from the chemical immobilization of catalysts (Pt nanoparticles) and electron transfer-enlarging materials (carbon nanotubes) on an electrode. Especially, dendrimers raise the stable conjugation of enzymes (acetylcholinesterase/choline oxidase/peroxidase) as well as nanoparticles and carbon nanotubes on an electrode.
Naoki Nagatani, Keiichiro Yamanaka, Hiromi Ushijima, Ritsuko Koketsu, Tadahiro Sasaki, Kazuyoshi Ikuta, Masato Saito, Toshiro Miyahara, Eiichi Tamiya, Detection of influenza virus using a lateral flow immunoassay for amplified DNA by a microfluidic RT-PCR chip, Analyst, 137, 3422, 2012
Influenza virus RNA was amplified by a continuous-flow polydimethylsiloxane microfluidic RT-PCR chip within 15–20 min. The amplified influenza virus RNA was observed with the naked eye, as the red color at the test line, using a lateral flow immunoassay within 1 min.
Keiichiro Yamanakaa, Tomohiko Ikeuchi, Masato Saito, Naoki Nagatani, Eiichi Tamiya, Electrochemical detection of specific DNA and respiratory activity of Escherichia coli, Electrochimica Acta, 62, 132, 2012
We present two rapid and simplified detection methods for Escherichia coli involving the use of a hand-held potentiostat and a disposable screen-printed carbon electrode. E. coli is one of the indicator organisms used to access for food safety. Commonly, microbiological culture techniques take more than one day to yield results and therefore, a simple, cost-effective, in situ detection system is required for testing food safety. This report describes two complementary techniques for high- and low-sensitivity detection of E. coli. High-sensitivity detection relies upon quantification of DNA amplification by using polymerase chain reaction (PCR), while the simplified, low-sensitivity detection can be obtained through measurement of oxygen consumption due to respiration; importantly, both techniques utilize the same type of electrode. The former entails mixing the PCR mixture with Hoechst, an electro-active DNA intercalator, and then, measuring the oxidation current. Binding of Hoechst molecules to the amplified DNA causes the peak current to decrease because of the slow diffusion of the Hoechst-amplified DNA complex to the electrode surface. The results showed that the oxidation peak current of Hoechst decreased depending on the number of E. coli cells added to the PCR mixture as the template for amplification, and the sensitivity of the method was as low as a single bacterium. Oxygen consumption was detected by direct measurement of the cell-containing culture medium. This method required only 10 μL to be applied on the screen-printed electrode, and the reduction in oxygen current was clearly observed within 30 min when a minimum of 1 × 105 cells were present. These results were obtained without purifying the culture, and the samples were applied onto the electrode without any surface modifications. The techniques describes in this report are versatile, because they require the same type of electrode, have simplistic nature, use a hand-held potentiostat, and have potential to provide an in situ system for assessing food safety.
他59報
学会発表
尚紀, 後藤 香秋, 肥塚 莉菜, 紙ベース酵素センサを用いたチロシナーゼ活性阻害検出, 第75回日本生物工学会大会, 2023/09/03
尚紀 肥塚 梨菜, 酵素活性阻害を利用した紙ベースセンサ, 日本分析化学会第71年会, 2022/09/14
永谷尚紀，岡本雅史，佐野翔子，藤原拓音, 紙をベースとしたセンサによる酵素活性測定, 日本生物工学会西日本支部大会, 2020/11/14
永谷 尚紀・寺本 尚矢・木下 誠也, 紙製マイクロ流体デバイスを用いたセンサの開発, 第13回バイオ関連化学シンポジウム, 2019/09/06