Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

We prepared network polysaccharide nanoscopic hydrogels by crosslinking water-soluble chitosan (WSCS) with a carboxylate-terminated maltooligosaccharide crosslinker via condensation. In this study, the enzymatic elongation of amylose chains on chitosan-based network polysaccharides by glucan phosphorylase (GP) catalysis was performed to obtain assembly materials. Maltoheptaose (Glc7) primers for GP-catalyzed enzymatic polymerization were first introduced into WSCS by reductive amination. Crosslinking of the product with the above-mentioned crosslinker by condensation was then performed to produce Glc7-modified network polysaccharides. The GP-catalyzed enzymatic polymerization of the α-d-glucose 1-phosphate monomer from the Glc7 primers on the network polysaccharides was conducted, where the elongated amylose chains formed double helices. Enzymatic disintegration of the resulting network polysaccharide assembly successfully occurred by α-amylase-catalyzed hydrolysis of the double helical amyloses. The encapsulation and release of a fluorescent dye, Rhodamine B, using the CS-based network polysaccharides were also achieved by means of the above two enzymatic approaches.

DOI： 10.3390/molecules29081804

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PubMed

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1038/s41428-024-00911-y

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Other Link： https://www.nature.com/articles/s41428-024-00911-y

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Recently, environmentally degradable polymers have received great attention from the perspective of sustaining the aquatic environment. To control the degradation behavior of solid polymer materials in an aqueous phase, it is crucial to better understand the thermal molecular motion of polymer chains in water. We herein focus on polyglycolide (PGA), which is one of the representative aliphatic polyesters that are hydrolytically degradable. Three kinds of fiber mats of PGA with different fiber diameters and comparable crystallinities were prepared using an electrospinning method. Our choice of fiber mats was because the ratio of the surface area, where the hydrolytic degradation starts to occur, to the volume was larger than that for the films. Dynamic mechanical analysis (DMA) enabled us to gain direct access to the dynamic glass transition temperature (Tg & alpha;) of PGA in the fiber mats both in dry gaseous nitrogen and liquid water. The Tg & alpha; value varied not only with the presence of water molecules, but also with the fiber diameter, or the specific surface area. The degradation behavior of PGA fiber mats was examined by immersing the samples in phosphate-buffered saline at various temperatures. When the segmental motion of PGA in the fiber mats was released, the apparent crystallinity of the mats increased, meaning that PGA amorphous chains were cleaved and thus partially eluted into the aqueous phase. It was also shown that partially cleaved chains crystallized.The release of segmental motion of polyglycolide in fiber mats caused cleavage and partial elution of chains into aqueous phases.

DOI： 10.1039/d3sm00613a

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PubMed

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Polymer adhesion with inorganic materials is a key technology for realizing the diversification of materials. When a polymer contacts with inorganic materials, a layer containing strongly- and loosely-adsorbed chains is formed at the surface. The former and latter are chains that adopt mainly train and loop/tail conformations, respectively. To improve the interfacial adhesion, it is of pivotal importance to control the interaction between loosely-adsorbed chains, which are in part directly attached to the solid surface, and bulk free chains. We here succeeded in increasing the interfacial strength by chemically cross-linking them. Polymer chains were attached to the surface of a silicon wafer and then a film of isotactic polypropylene or polyamide 6 was mounted on it to produce our model system. As loosely-adsorbed chains have photo-cross-linkable moieties, the polyolefin or engineering plastic film could be strongly adhered to the silicon wafer via the adsorbed layer. On the other hand, the film could be easily detached from the wafer having loosely-adsorbed chains without photo-cross-linkable groups. Our facile idea that loosely-adsorbed interfacial chains chemically bond to the polymer bulk shows promise for the design and construction of not only interfacial adhesion but also composite materials.

DOI： 10.1016/j.polymer.2022.125581

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

The mechanical properties in the outermost region of a polymer film strongly affect various material functions. We here propose a novel and promising strategy for the two-dimensional regulation of the mechanical properties of a polymer film at the water interface based on an inkjet drawing of silica nanoparticles (SNPs) underneath it. A film of poly(2-hydroxyethyl methacrylate) (PHEMA), which exhibits excellent bioinertness properties at the water interface, was well fabricated on a substrate with a pattern of SNPs. X-ray photoelectron spectroscopy and atomic force microscopy confirmed that the surface of the PHEMA film was flat and chemically homogeneous. However, the film surface was in-plane heterogeneous in stiffness due to the presence of the underlying SNP lines. It was also noted that NIH/3T3 fibroblast cells selectively adhered and formed aggregates on the areas under which an SNP line was drawn.

DOI： 10.1021/acs.langmuir.1c02776

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PubMed

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publisher：Tokyo : Springer Nature  

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publisher：Tokyo : Springer Nature  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGERNATURE  

A better understanding of the aggregation states of polymers in contact with water is a pivotal issue for the development of highly functional polymer devices that work under water. As a direct experimental method to achieve the above, we used near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) on a poly(methyl methacrylate) (PMMA) film mixed with a small amount of a bottlebrush-type methacrylate polymer with oligo(2-ethyl-2-oxazoline) in its side chain portions, referred to as P[O(Ox)(n)MA], in a hydrated state. The results showed that P[O(Ox)(n)MA] was segregated at the surface of the PMMA film and suppressed the adhesion and activation of platelets on the film.

DOI： 10.1038/s41428-021-00485-z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGERNATURE  

Surface modification of versatile polymeric materials without changing their bulk properties is one of the essential techniques for regulating their physical and chemical characteristics, and this technique can improve the functions of materials. In this study, a bottlebrush-type poly[oligo(2-ethyl-2-oxazoline) methacrylate] (P[O(Ox)(n)MA]) (n = 7 and 19) was synthesized as a surface modifier. This compound was mixed into poly(methyl methacrylate) (PMMA) as a matrix (PMMA/P[O(Ox)(n)MA]) with a weight ratio of 15%, and the aggregation state in the surface region was examined under air and aqueous environments via atomic force microscopy, contact angle measurement, angular-dependent X-ray photoelectron spectroscopy, and neutron reflectivity. The surface of the PMMA/P[O(Ox)(n)MA] films was flat at the subnanometer level and covered with the PMMA-rich phase. However, once the films contacted water, the surface was reorganized due to the migration of P[O(Ox)(n)MA]. The extent of the surface segregation was more remarkable for P[O(Ox)(7)MA] than P[O(Ox)(19)MA] due to the entropic factor. Concurrently, NIH3T3 fibroblast adhesion and serum protein adsorption on the film were more strongly suppressed for P[O(Ox)(7)MA] than P[O(Ox)(19)MA] because it formed a thicker diffused interface in the film with water.

DOI： 10.1038/s41428-020-00459-7

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