論文 - 臼井 健二
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One-Pot Synthesis and Immobilization of Gold Nanoparticles Using Peptidyl Microbeads 査読あり 国際誌
Shuhei Yoshida, Koki Yoshida, Taichi Isozaki, Maho Oura, Makoto Ozaki, Takaaki Tsuruoka, Kenji Usui
Molecules 30 1689 2025年4月
Gold nanoparticles (AuNPs) have surface plasmon resonance (SPR) and catalytic activity that are not found in bulk gold and have been studied in various fields. Among these, immobilization of AuNPs on various solid-phase substrates is known to produce stable catalytic activity and specific SPRs and research on the immobilization of AuNPs has been conducted actively. However, the conventional method requires the preparation and immobilization of AuNPs in separate processes, making it difficult to prepare immobilized AuNPs in a one-pot process. In this study, we attempted to synthesize and immobilize AuNPs using peptidyl beads, which are microbeads having immobilized a peptide capable of reducing gold ions. We successfully reduced Au ions from 0.5 to 1000 µM of HAuCl4 and immobilized them on peptidyl beads in the form of AuNPs. The immobilized AuNPs have a constant particle size independent of the HAuCl4 concentration. Furthermore, the peptidyl beads with AuNPs have catalytic activity. The quantity of the AuNPs on the peptidyl beads and, subsequently, the catalytic reaction rate of the sample, could be controlled. This study would also be expected to be applied to the immobilization of metallic nanomaterials other than AuNPs by modifying the peptide sequence.
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Development of detection system for lead ions in mixture solutions using UV-Vis measurements with peptide immobilized microbeads 査読あり 国際誌
Shuhei Yoshida, Koki Yoshida, Yoshio Hamada, Takaaki Tsuruoka, Kenji Usui
Scientific Reports 15 3249 2025年1月
Environmental pollution caused by heavy metals are problems worldwide. In particular, pollution and poisoning by lead ions (Pb2+) continue to be common and serious problems. Hence, there is a need for a widely usable method to easily detect Pb2+ from solutions containing organic materials from environmental water such as seas, ponds, etc. Here, we established a system to easily detect Pb2+ from such mixture solutions using Pb2+ binding peptide immobilized beads (peptidyl beads) and ultraviolet (UV) absorption measurements. This method could detect Pb2+ at low concentrations equivalent to inductively coupled plasmon-atomic emission spectroscopy (ICP-AES). Using the detected values to create a calibration curve, it was found that there was a positive correlation between the concentration of Pb2+ and absorbance, which also made it possible to quantify sub-µM Pb2+ in the solutions. Furthermore, Pb2+ was detected and quantified under mixed conditions of environmental water such as seas, rivers, and ponds. This method is expected to become a versatile and easy-to-use Pb2+ detection method for end-users worldwide.
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Complex and Non-sequential Current Signatures of a β-Hairpin Peptide Confined in a Nanopore 国際共著 国際誌
Misa Yamaji, Mauro Chinappi, Blasco Morozzo della Rocca, Kenji Usui, Ryuji Kawano
Analytical Chemistry 97 2044 - 2051 2025年1月
出版者・発行元：American Chemical Society (ACS)
Nanopore sensing is widely used for single-molecule detection, originally applied to nucleic acids and now extended to protein sensing. Our study focuses on the complex conformational changes of peptides in nanopores, which may have implications for peptide fingerprinting and protein identification. Specifically, we investigated the interaction of a β-hairpin peptide (SV28) within an α-hemolysin (αHL) nanopore. Our experiments revealed that SV28 is captured via dielectrophoresis and exhibits long dwell times within the nanopore, leading to multiple current blockade levels. Unlike DNA hairpins, the peptide showed non-sequential transitions among four distinct blockade levels. This complex behavior indicates that the peptide dynamics in nanopores cannot be simply modeled along a single reaction coordinate. Our findings provide insights into peptide-nanopore interactions, which are potentially useful for developing nanopore-based peptide identification technologies.
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Development of a CaCO3 Precipitation Method Using a Peptide and Microwaves Generated by a Magnetron 査読あり
Fumihiro Kayamori, Hiroyuki Togashi, Natsumi Endo, Makoto Ozaki, Kan Hirao, Yonejiro Arimoto, Ryuji Osawa, Takaaki Tsuruoka, Takahito Imai, Kin-ya Tomizaki, Tomohiro Umetani, Nobuhiro Nakanishi, Kenji Usui
Processes 12 1327 - 1327 2024年6月
出版者・発行元：MDPI AG
Microwave applications, such as microwave ovens and mobile phones, are ubiquitous and indispensable in modern society. As the utilization of microwave technology is becoming more widespread, the effects of microwaves on living organisms and physiological processes have received increased attention. This study aimed to investigate the effects of microwaves on calcium carbonate biomineralization as a model biochemical process. A magnetron oscillator was used to generate 2450 MHz microwaves because magnetrons are relatively inexpensive and widespread. We conducted transmission electron microscopy (TEM), atomic force microscopy (AFM), TEM-electron energy-loss spectroscopy (EELS), dynamic light scattering (DLS), and high-performance liquid chromatography (HPLC) measurements to analyze the calcium carbonate precipitates. Our findings showed the formation of string-like precipitates of calcium carbonate upon microwave irradiation from one direction, similar to those obtained using a semiconductor oscillator, as reported previously. This implied that the distribution of the frequency had little effect on the morphology. Furthermore, spherical precipitates were obtained upon microwave irradiation from two directions, indicating that the morphology could be controlled by varying the direction of microwave irradiation. Magnetrons are versatile and also used in large-scale production; thus, this method has potential in medical and industrial applications.
DOI： 10.3390/pr12071327
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Effect of linearly polarized microwaves on nanomorphology of calcium carbonate mineralization using peptides 査読あり
Kenji Usui, Makoto Ozaki, Kan Hirao, Tsubasa Kosaka, Natsumi Endo, Shuhei Yoshida, Shin-ichiro Yokota, Yonejiro Arimoto, Ryuji Osawa, Nobuhiro Nakanishi, Kin-ya Tomizaki, Tomohiro Umetani, Fumihiro Kayamori
Scientific Reports 13 12027 2023年7月
Microwaves are used for diverse applications such as mobile phones, ovens, and therapy devices. However, there are few reports on the effects of microwaves on diseases other than cancer, and on physiological processes. Here, we focused on CaCO3 mineralization as a model of biomineralization and attempted to elucidate the effect of microwaves on CaCO3 mineralization using peptides. We conducted AFM, ζ potential, HPLC, ICP-AES, and relative permittivity measurements. Our findings show that microwaves alter the nanomorphology of the CaCO3 precipitate, from sphere-like particles to string-like structures. Furthermore, microwaves have little effect on the mineralization when the mineralization ability of a peptide is high, but a large effect when the precipitation ability is low. Our findings may be applicable to not only the treatment of teeth and bones but also the development of organic–inorganic nanobiomaterials. This methodology can be expanded to other molecular/atomic reactions under various microwave conditions to alter reaction activity parameters.
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Construction of a Method to Design Fibril-Forming Peptides Applied to Biomaterials from 20 Beta-Sheet Peptides by Statistical Analysis 査読あり
Kazuya Iwata, Taisei Terao, Akira Takekawa, Tomohiro Umetani, Kenji Usui
Peptide Science 2022 141 - 142 2023年3月
担当区分：最終著者, 責任著者
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De novo design of a nanopore for single-molecule detection that incorporates a β-hairpin peptide. 査読あり 国際共著 国際誌
Keisuke Shimizu, Batsaikhan Mijiddorj, Masataka Usami, Ikuro Mizoguchi, Shuhei Yoshida, Shiori Akayama, Yoshio Hamada, Akifumi Ohyama, Kenji Usui, Izuru Kawamura, Ryuji Kawano
Nature nanotechnology 17 67 - 75 2022年1月
The amino-acid sequence of a protein encodes information on its three-dimensional structure and specific functionality. De novo design has emerged as a method to manipulate the primary structure for the development of artificial proteins and peptides with desired functionality. This paper describes the de novo design of a pore-forming peptide, named SV28, that has a β-hairpin structure and assembles to form a stable nanopore in a bilayer lipid membrane. This large synthetic nanopore is an entirely artificial device for practical applications. The peptide forms multidispersely sized nanopore structures ranging from 1.7 to 6.3 nm in diameter and can detect DNAs. To form a monodispersely sized nanopore, we redesigned the SV28 by introducing a glycine-kink mutation. The resulting redesigned peptide forms a monodisperse pore with a diameter of 1.7 nm leading to detection of a single polypeptide chain. Such de novo design of a β-hairpin peptide has the potential to create artificial nanopores, which can be size adjusted to a target molecule.
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ウォッシャーディスインフェクターのすすぎ排水中に含まれる洗浄剤残留量の測定によるすすぎ性能評価 査読あり
三軒隼人、藤田敏、川田原瑠勇、武川公、臼井健二、原田陽滋
医療機器学 91 315 - 332 2021年8月
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Ozaki, M., Yoshida, S., Tsuruoka, T., Usui, K.
Chemical Communications 57 2021年
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Ozaki, M., Imai, T., Tsuruoka, T., Sakashita, S., Tomizaki, K.-Y., Usui, K.
Communications Chemistry 4 2021年
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Miyazaki H , Hamada Y , Takaishi H , Minamino Y , Ikeda H , Mekata H , Takaishi M , Yamashita K , Usui K
Analyst 145 3211 - 3216 2020年5月
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Novel purification process for amyloid beta peptide(1-40) 招待あり 査読あり
Usui, K., Yokota, S.-I., Iwata, K., Hamada, Y.
Processes 8 2020年
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Miyazaki, H., Takaishi, H., Ikeda, H., Ariumi, H., Hamada, Y., Yamashita, K., Usui, K.
Processes 8 2020年
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Miyazaki, H., Samejima, Y., Iwata, K., Minamino, Y., Hikida, S., Ariumi, H., Ikeda, H., Hamada, Y., Yamashita, K., Usui, K.
International Journal of Molecular Sciences 21 2020年
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Effect of tryptophan residues on gold mineralization by a gold reducing peptide 査読あり 国際誌
Ozaki, M., Yoshida, S., Oura, M., Tsuruoka, T., Usui, K.
RSC Advances 10 2020年
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Kenji Usui, Shin-ichiro Yokota, Makoto Ozaki, Shungo Sakashita, Takahito Imai, Kin-ya Tomizaki
Protein & Peptide Letters 25 42 - 47 2018年4月
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Yuki Tominaga, Kenji Usui, Akiyoshi Hirata, Hiro-O Ito, Kiyoshi Nokihara
Bioorganic & Medicinal Chemistry 26 3210 - 3216 2018年4月
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Editorial: Organic-Inorganic Hybrid Materials and Their Applications 査読あり
Kin-ya Tomizaki, Yoshio Hamada, Kenji Usui
Protein & Peptide Letters 25 2 - 3 2018年4月
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Peptides for Silica Precipitation: Amino Acid Sequences for Directing Mineralization 査読あり
Makoto Ozaki, Shungo Sakashita, Yoshio Hamada, Kenji Usui
Protein & Peptide Letters 25 15 - 24 2018年4月
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Design of Anti-Alzheimer's Disease Agents Focusing on a Specific Interaction with Target Biomolecules 査読あり
Yoshio Hamada, Kenji Usui
Neuromethods 132 207 - 228 2018年