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工学教育研究部 工学科応用物質化学プログラム担当 |
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Preparation of Nanochitin from Crickets and Comparison with That from Crab Shells 査読あり
Kishida K., Mizuta T., Izawa H., Ifuku S.
Journal of Composites Science 6 ( 10 ) 2022年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Composites Science
Crickets are gaining worldwide attention as a nutrient source with a low environmental impact. We considered crickets as a new source of chitin raw material. Chitin isolated from crickets was successfully converted to nanochitin by pulverization. First, chitin was obtained from cricket powder in a 2.6% yield through a series of chemical treatments. Chitin identification was confirmed by FT-IR and 13C NMR. The chitin had an α-type crystal structure and a deacetylation degree of 12%. Next, it was pulverized in a disk mill to obtain nanochitin. Cricket nanochitin was of a whisker shape, with an average fiber width of 10.1 nm. It was larger than that of crab shells, while the hydrodynamic diameter and crystal size were smaller. Such differences in shape affected the physical properties of the dispersion. The transmittance was higher than that of crab nanochitin due to the size effect, and the viscosity was smaller. Moreover, the dry non-woven cricket nanochitin sheets were more densely packed, and their modulus and breaking strength were greater.
DOI： 10.3390/jcs6100280
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Izawa H., Ishisaka S., Saimoto H., Ifuku S.
Bulletin of the Chemical Society of Japan 95 ( 9 ) 1289 - 1295 2022年9月
担当区分：筆頭著者, 責任著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Bulletin of the Chemical Society of Japan
The effects of the physical properties of skin layers and substrates on drying-induced surface wrinkling are investigated with a system using chitosan films having polyion complex (PIC) skin layers. The PIC layers are fabricated with diverse anionic polymers having similar molecular weights on a chitosan (CS) film surface, and the films are dried. In all cases, surface wrinkles form but their sizes vary widely depending on the molecular structure. In particular, wrinkles formed with ligninsulfonate are much larger than those formed with the others. The skin layers differ significantly in surface hardness but not in thickness, indicating that wrinkle sizes induced by PIC skin layers are predominately determined by the hardness of the layers or by physical properties affected by hardness, such as shrinkage volume. The effects of the elastic moduli and shrinkage volume of the substrates are evaluated with higher molecular weight CS and surface-deacetylated chitin nanofiber composite CS films that have different elastic moduli but show very similar swellingdrying behaviors. The wrinkle sizes and skin layer thicknesses also suggest that wrinkle size in this system depends on the hardness of the skin layers or on the physical properties affecting the hardness.
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Optimization of Chitin Nanofiber Preparation by Ball Milling as Filler for Composite Resin 査読あり
Zewude D.A., Izawa H., Ifuku S.
Journal of Composites Science 6 ( 7 ) 2022年7月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Composites Science
Chitin nanofiber is a nanomaterial produced by pulverizing chitin, the main component of crab shells. Since it has excellent mechanical properties, it is expected to be used as a reinforcing material to strengthen materials. Chitin was mechanically ground in water using a ball mill to prepare nanofibers. The ball size, total ball weight, and milling time were varied, and the resulting water dispersion and the cast film were analyzed to optimize the conditions for efficient preparation. The length and width of the nanofibers were also measured by SEM and AFM observations. The size of the balls affected the level of grinding and the intensity of impact energy on the chitin. The most efficient crushing was achieved when the diameter was 1 mm. The total ball weight directly affects the milling frequency, and milling proceeds as the total weight increases. However, if too many balls occupy the container, the grinding efficiency decreases. Therefore, a total ball weight of 300 g was optimal. Regarding the milling time, the chitin becomes finer depending on the increase of that time. However, after a specific time, the shape did not change much. Therefore, a milling time of approximately 150 min was appropriate.
DOI： 10.3390/jcs6070197
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Izawa H., Yasufuku F., Matsumoto T., Ifuku S., Saimoto H., Sumita M.
Tetrahedron Letters 100 2022年6月
担当区分：筆頭著者, 責任著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Tetrahedron Letters
Here we show a novel colorimetric sensor system with a photo-induced colorimetric reaction of N,N'-bis[2-(trimethylammonium)ethyl]-1,8:4,5-naphthalenetetracarboxdiimide (TENDI) to detect and quantify carboxylate derivatives. In the presence of CH3COONa, TENDI aqueous solution under UV irradiation shows a photo-induced colorimetric reaction, which is due to the production of naphthalenediimide (NDI)-based radical anions whose absorbance peaks appear at around 400–600 nm. In contrast, no color changes are observed in the cases of diverse inorganic salts. In addition, TENDI shows another ability to discriminate the structural features of carboxylate derivatives by color tone. Moreover, interestingly, the Hill equation can approximate the relationship between carboxylate concentrations and absorbance values on the maximum absorbance wavelengths of the absorbance peaks due to the NDI-radical anions.
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Production of chitin nanoparticles by bottom-up approach from alkaline chitin solution 査読あり
Dagmawi Abebe Zewude, Takako Noguchi, Kimihiko Sato, Hironori Izawa, Shinsuke Ifuku
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES 210 123 - 127 2022年6月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：ELSEVIER
Most of the series of nanochitins have been produced by the break-down process. In this study, chitin nanoparticles were prepared by a bottom-up process. Chitin was treated with sodium hydroxide to obtain an alkaline chitin aqueous solution. The alkaline chitin was regenerated by neutralization and then vigorously stirred to obtain chitin nanoparticles. The average particle size of the chitin nanoparticles was 7 nm. The individual particles were stably dispersed in water. Chitin nanoparticles had lower crystallinity than the raw material chitin and the surface of the chitin nanoparticles regenerated in water were presumed to be hydrophilic. The low crystallinity and the high hydrophilicity of the surface contributed to the high dispersibility of the chitin nanoparticles in water. Chitin nanoparticles had higher heat resistance than the raw material chitin, suggesting a large change in the higher-order structure associated with dissolution and subsequent regeneration of chitin. Since chitin nanoparticles interact with each other less than chitin nanofibers produced by mechanical treatment, the viscosity of nanoparticles was smaller than that of nanofibers. Therefore, it can be prepared at a high concentration. In addition, the chitin nanoparticles can be easily redispersed in water after being concentrated by centrifugation.
科研費（文科省・学振・厚労省）獲得実績 【 表示 ／ 非表示 】
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微細構造表面を誘起するスキン層の科学の開拓
研究課題/領域番号：19K05616 2019年04月 - 2022年03月
日本学術振興会 科学研究費助成事業 基盤研究(C) 基盤研究(C)
井澤 浩則
担当区分：研究代表者