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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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Homogeneous microscopic bumps generated on λ-carrageenan cast film surface
Izawa H., Toyoshima Y., Fujiwara N., Kawakami M., Tajima W., Ifuku S.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 690 2024年6月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Colloids and Surfaces A: Physicochemical and Engineering Aspects
Here we investigate the phenomenon of bump formation on λ-carrageenan (CG). In this phenomenon, microscopic bumps (ca. 2.8 µm wide and ca. 0.4 µm high) form on the surface of λ-CG cast film created by evaporating a 1.0 wt% λ-CG solution in a PTFE petri dish at 60 ºC. We observe that the size of the bumps can be controlled by adjusting the concentration and volume of the λ-CG solution, and this is correlated with the film thickness. Specifically, as the film thickness increases, the size of the bumps also increases with strong correlation. We also investigate the mechanism underlying bump formation. We find that bumps form by complete drying and that the λ-CG film exhibits less-adhered inner layers with periodic curves resembling the bumps. These results suggest the curved layer structure is related to the formation mechanism. In other words, the drying shrinkage strain is relieved on each layer through curving, leading to the generation of bumps on the free surface. Therefore, we hypothesize that the fundamental mechanism behind the formation of these bumps lies in the self-organization of λ-CG, which results in the creation of an adhesion-less layered structure during the cast film formation process.
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Melanin Upcycling: Creation of Polymeric Materials from Melanin Decomposition Products
Morita T., Matsuura T., Izawa H., Kishikawa K., Kohri M.
ACS Sustainable Chemistry and Engineering 12 ( 18 ) 7115 - 7125 2024年5月
掲載種別：研究論文（学術雑誌） 出版者・発行元：ACS Sustainable Chemistry and Engineering
Melanin is a widely occurring biopolymer and has been the subject of much research, especially in dermatology. However, from a resource perspective, melanin is still an unutilized biomass because of its complex three-dimensional cross-linked structure, which makes it challenging to handle. Here, we demonstrate melanin upcycling by decomposing melanin and preparing polymeric materials from its products. A detailed study of the chemical decomposition products of artificial melanin, i.e., polydopamine, reveals that the melanin decomposition products are mainly oligomeric pyrrole derivatives containing carboxylic acids. Furthermore, decomposition experiments using natural melanin extracted from cuttlefish ink revealed that the composition of melanin decomposition products is almost identical regardless of the melanin source. We proposed a melanin decomposition mechanism and demonstrated the preparation of biobased polymer films and particles from melanin decomposition products. The use of melanin decomposition products as building blocks for material preparation is expected to lead to the development of new biodegradable polymers from biomass.
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Khan N.F., Nakamura H., Izawa H., Ifuku S., Kadowaki D., Otagiri M., Anraku M.
Journal of Functional Biomaterials 14 ( 7 ) 2023年7月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Functional Biomaterials
Arginine-rich membrane-permeable peptides (APPs) can be delivered to cells by forming complexes with various membrane-impermeable bioactive molecules such as proteins. We recently reported on the preparation of guanidinylated chitosan (GCS) that mimics arginine peptides, using chitosan, a naturally occurring cationic polysaccharide, and confirmed that it enhances protein permeability in an in vitro cell system. However, studies on the in vivo safety of GCS are not available. To address this, we evaluated the in vivo safety of GCS and its translocation into the gastrointestinal tract in rats after a single oral administration of an excessive dose (500 mg/kg) and observed changes in body weight, major organ weights, and organ tissue sections for periods of up to 2 weeks. The results indicated that GCS causes no deleterious effects. The results of an oral administration of rhodamine-labeled chitosan and an evaluation of its migration in the gastrointestinal tract suggested that the disappearance of rhodamine-labeled GCS from the body appeared to be slower than that of the non-dose group and pre-guanidinylated chitosan due to its mucoadhesive properties. In the future, we plan to investigate the use of GCS to improve absorption using Class III and IV drugs, which are poorly water-soluble as well as poorly membrane-permeable.
DOI： 10.3390/jfb14070340
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Water-soluble guanidinylated chitosan: a candidate material for protein delivery systems 査読あり
Izawa H., Yagi A., Umemoto R., Ifuku S.
Polymer Journal 55 ( 8 ) 885 - 895 2023年
掲載種別：研究論文（学術雑誌） 出版者・発行元：Polymer Journal
Here, we introduce water-soluble guanidinylated chitosan (WGCS) as a candidate material for protein delivery systems to enhance the cellular internalization of protein/peptide drugs. A WGCS composed of 48.2% guanidinylated chitosan, 20.6% chitosan, and 31.2% chitin units was prepared with a low-molecular-weight chitosan (CS) lactate via a guanidinylation reaction with 1-amidinopyrazole hydrochloride. The Mn of WGCS was estimated by gel permeation chromatography analysis to be 7.6 × 103 (Mw /Mn = 1.5). The higher chitin content in WGCS than in common CS (<20%) is an important factor in achieving water solubility. WGCS showed ca. 2.5-fold higher internalization into HeLa cells than CS does. This clearly indicated that guanidinylation enhances internalization. In addition, endocytic pathways were suggested as a mechanism underlying internalization. Moreover, WGCS significantly enhanced the internalization of bovine serum albumin (BSA) in transport medium at pH 7.4 containing BSA: the internalized amount of BSA in the presence of WGCS was ca. 2-fold higher than in the presence of CS. This higher internalization was caused by efficient binding between WGCS and BSA via electrostatic interactions owing to the guanidino groups. Indeed, the affinity of the binding sites of WGCS is more than 10-fold higher than that of the binding sites of CS.
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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
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
その他競争的資金獲得実績 【 表示 ／ 非表示 】
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グアニジル化キトサンライブラリの構築
2024年08月 - 2026年03月
国立研究開発法人新エネルギー・産業技術総合開発機構 （NEDO） 官民による若手研究者発掘支援事業／マッチングサポートフェーズ（NEDO）
担当区分：研究代表者