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Journal Articles

Nanocellulose hydrogels formed via crystalline transformation from cellulose I to II and subsequent freeze cross-linking reaction

Sekine, Yurina; Nankawa, Takuya; Hiroi, Kosuke; Oba, Yojiro*; Nagakawa, Yoshiyasu*; Sugita, Tsuyoshi; Shibayama, Yuki; Ikeda-Fukazawa, Tomoko*

Carbohydrate Polymers, 327, p.121538_1 - 121538_11, 2024/03

We describe non-toxic, tough nanocellulose (NC) hydrogels formed from chemically unmodified NC by cellulose crystalline transformation and subsequent freeze cross-linking reaction. Using low-concentration NaOH and freezing together induced the crystalline transformation of NC from cellulose I to II via freeze concentration. After the crystalline transformation, cross-linking between the NC and CA in the freeze concentration layer (FCL) provided a strong NC network structure, forming NC hydrogels with high mechanical strength. The freeze-cross-linked NC hydrogel easily retained powder adsorbents in its inner space by mixing the NC-NaOH sol and the powder, and the hydrogel showed high removal efficiency for heavy metals. The results highlight the versatility of chemically unmodified celluloses in developing functional materials, suggest possible practical applications.

Journal Articles

Development of tough cellulose hydrogels using freeze-concentrated layers

Sekine, Yurina

Cellulose Communications, 30(4), p.203 - 208, 2023/12

In this paper, we introduce the fabrication and properties of carboxymethyl cellulose nanofiber (CMCF) hydrogels with high compression recoverability, macroporosity, and nontoxic properties by utilizing the phase separation phenomenon of ice crystals and solutes that occurs during freezing of aqueous solutions. The features of the developed freeze cross-linked CMCF hydrogel include that it can be made from harmless raw materials with simple procedure, high water content, and biodegradability. By taking advantage of these properties, this hydrogel synthesis technique can contribute to expanding the use of cellulose derivatives as environmental purifiers, functional materials, etc.

Journal Articles

Upgrade of the small-angle neutron scattering diffractometer SANS-J at JRR-3

Kumada, Takayuki; Motokawa, Ryuhei; Oba, Yojiro; Nakagawa, Hiroshi; Sekine, Yurina; Micheau, C.; Ueda, Yuki; Sugita, Tsuyoshi; Birumachi, Atsushi; Sasaki, Miki; et al.

Journal of Applied Crystallography, 56(6), p.1776 - 1783, 2023/12

The combination of the existing position-sensitive photomultiplier and the 3He main detector with focusing devices, and the newly installed front detectors in SANS-J at JRR-3 covers small-angle neutron scattering signals in the range of the magnitude of the scattering vector Q from 0.002 to 6 nm-1 gaplessly with three standard device layouts. The installation of the front detector and a graphical user interface system largely improved the usability of SANS-J.

Journal Articles

Freeze-concentrated layers as a unique field for the formation of hydrogels

Sekine, Yurina; Nankawa, Takuya

Bulletin of the Chemical Society of Japan, 96(10), p.1150 - 1155, 2023/10

The phase separation of ice crystals and solutes and bound water that occurs during freezing can be used as a reaction field to control a hierarchical structure of hydrogels. Here, we present a study of carboxymethyl cellulose nanofiber (CMCF) hydrogels formed using the solid-quasi liquid phase separation. CMCF hydrogels were formed simply by adding citric acid to frozen CMCF and thawing the mixture. It was found that rearrangement of CMCF structures via hydrogen bonding proceeds in the freeze concentration layer before the ice crystals melt. Under freeze concentration, CMCF and bound water are confined at high concentrations. The crosslinking reaction in such a unique space contributed to the formation of CMCF hydrogel with high mechanical strength. We discuss the gelation behavior and properties of freeze crosslinked CMCF hydrogels and their applications.

Journal Articles

Novel hydrogel properties by microstructural control of carboxymethyl cellulose nanofibers using freezing

Sekine, Yurina

Fain Kemikaru, 52(8), p.25 - 32, 2023/08

By using the freezing phenomenon, we discovered that a hydrogel with high compressive strength can be formed using only harmless materials, mainly carboxymethyl cellulose nanofibers. The key is the phase separation of ice crystals and solutes that occurs when aqueous solutions freeze. This paper describes the formation mechanism of the freeze crosslinked hydrogel and its properties.

Journal Articles

Polarized neutrons observed nanometer-thick crystalline ice plates in frozen glucose solution

Kumada, Takayuki; Nakagawa, Hiroshi; Miura, Daisuke; Sekine, Yurina; Motokawa, Ryuhei; Hiroi, Kosuke; Inamura, Yasuhiro; Oku, Takayuki; Oishi, Kazuki*; Morikawa, Toshiaki*; et al.

Journal of Physical Chemistry Letters (Internet), 14(34), p.7638 - 7643, 2023/08

The structure of nano-ice crystals in rapidly frozen glucose solution was elucidated by using spin-contrast-variation small-angle neutron scattering, which distinguishes the nano-ice crystal signal from the frozen amorphous solution signal by the polarization-dependent neutron scattering. The analysis revealed that the nano-ice crystals form a planar structure with a diameter exceeding tens of nanometers and a thickness of 1 nm, which is close to the critical nucleation size. This result suggests that the glucose molecules are preferentially bound to a specific face of nano-ice crystals, and then block the crystal growth perpendicular to that face.

Journal Articles

Fractionation of hydrogen isotopes in a hydrogel during dehydration

Watanabe, Teppei*; Sekine, Yurina; Ikeda-Fukazawa, Tomoko*

Macromolecules, 56(16), p.6217 - 6221, 2023/08

To investigate the ability of hydrogels to separate hydrogen isotopes in water, we analyzed the Raman spectra of poly-N,N-dimethylacrylamide (PDMAA) hydrogels containing deuterated water during dehydration. The results show a significant fractionation of hydrogen isotopes during dehydration. The D molar ratio of the hydrogel increases from 0.056 to $$sim$$0.2 during dehydration from 90.5 wt% to 5 wt% in water content. Deuterated water preferentially forms hydrogen bonds with hydrophilic groups of the polymer in hydrogels because of the difference in strengths of hydrogen bonds between protium and deuterium. As a result, normal water preferentially evaporates in the initial stage of dehydration, leaving deuterated water in the drying hydrogel. The results suggest that hydrogels are an efficient material for isotope fractionation with evaporation.

Journal Articles

Soft, environmentally degradable microfluidic devices for measurement of sweat rate and total sweat loss and for colorimetric analysis of sweat biomarkers

Liu, S.*; Yang, D. S.*; Wang, S.*; Luan, H.*; Sekine, Yurina; Model, J. B.*; Aranyosi, A. J.*; Ghaffari, R.*; Rogers, J. A.*

EcoMat (Internet), 5(1), p.e12270_1 - e12270_18, 2023/01

 Times Cited Count:7 Percentile:92.24(Chemistry, Physical)

Advanced capabilities in noninvasive, in situ monitoring of sweat serve as the basis for obtaining real-time insights into human physiological state, health, and performance. Although recently reported microfluidic systems support powerful functions, most are designed as single-use disposables. Here, we introduce materials and molding techniques that bypass these concerns through biodegradable microfluidic systems with a full range of features. The key components fully degrade through the enzymatic action of microorganisms in natural soil environments. Detailed characterization of the device reveal a set of essential performance parameters that are comparable to, or even better than, those of non-degradable counterparts. Human subject studies illustrate the ability of these devices to acquire accurate measurements of sweat loss, sweat rate, pH, and chloride concentration.

Journal Articles

Microscopic structural changes during the freeze cross-linking reaction in carboxymethyl cellulose nanofiber hydrogels

Miura, Daisuke*; Sekine, Yurina; Nankawa, Takuya; Sugita, Tsuyoshi; Oba, Yojiro; Hiroi, Kosuke; Ozawa, Tatsuhiko

Carbohydrate Polymer Technologies and Applications (Internet), 4, p.100251_1 - 100251_9, 2022/12

The reaction mechanism of carboxymethyl cellulose nanofiber (CMCF) hydrogel formed by freeze-crosslinking was investigated. We succeeded in observing the hierarchical structural changes during the freeze-crosslinking reaction. Freeze-crosslinked CMCF hydrogels exhibited a characteristic hierarchical alignment structure from the angstrom to micrometer scale that differed from normal cross-linked CMCF hydrogels produced by a conventional method without freezing. It was shown that the characteristic hierarchical structure contributes the excellent mechanical properties of freeze-crosslinked CMCF hydrogels.

Journal Articles

Ion-selective adsorption of lead by a two-dimensional terbium oxalate framework

Nankawa, Takuya; Sekine, Yurina; Yamada, Teppei*

Bulletin of the Chemical Society of Japan, 95(5), p.825 - 829, 2022/05

 Times Cited Count:0 Percentile:18.08(Chemistry, Multidisciplinary)

Advances in hazardous metal ion removal are essential for wastewater clean-up to tackle the global water shortage crisis. Here, we report a Pb-selective adsorbent using a Tb oxalate framework (TOF) synthesized by a one-pot hydrothermal method. The TOF has a two-dimensional sheet structure, in which the interlayer space functions as an ion exchangeable site. Sorption tests using a mixed-ion solution containing Pb$$^{2+}$$, Cd$$^{2+}$$, Mn$$^{2+}$$, Co$$^{2+}$$, Ni$$^{2+}$$, Cu$$^{2+}$$, Na$$^{+}$$, K$$^{+}$$, Mg$$^{2+}$$, and Ca$$^{2+}$$ showed that the TOF has high selectivity for Pb$$^{2+}$$ among other metal ions. The saturated adsorption capacity of the TOF for Pb$$^{2+}$$ was 276 mg g$$^{-1}$$, which is higher than that of conventional adsorbents. Furthermore, the TOF exhibited reversible Pb$$^{2+}$$ adsorption/desorption and could be used for at least three cycles. The results showed that TOF has excellent potential as an adsorbent for removing Pb$$^{2+}$$, and because of its reusability, it is also a promising material for wastewater clean-up.

Journal Articles

Development of spin-contrast-variation neutron powder diffractometry for extracting the structure factor of hydrogen atoms

Miura, Daisuke*; Kumada, Takayuki; Sekine, Yurina; Oku, Takayuki; Takata, Shinichi; Hiroi, Kosuke; Iwata, Takahiro*

J-PARC 22-02; J-PARC MLF Annual Report 2021, p.6 - 7, 2022/03

We carried out spin contrast variation neutron powder diffractometry of glutamic acid crystal. The diffraction peak intensities varied as a function of proton polarization. We extracted the structure factor of hydrogen atoms from the variation of peak intensities.

Journal Articles

Eco-friendly cellulose nanofiber hydrogels prepared via freeze crosslinking and their applications

Sekine, Yurina

Kensetsu Kikai Seko, 74(2), p.94 - 97, 2022/02

This research has revealed that a high strength hydrogel can be prepared by adding an aqueous solution of citric acid to a frozen carboxymethyl cellulose nanofiber (CMCF) and then thawing the sol. The reaction between the freeze-concentrated CMCF and CA created a rigid porous structure, which resembled the ice crystal structure. The cellulose hydrogel material obtained through this technique exhibited sufficient strength along with a high level of moldability that allows it to be molded into different three-dimensional shapes. In addition, the material has the potential to be used as an adsorbent to remove hazardous substances.

Journal Articles

Super adsorbent for removing harmful metals using pig bone waste

Nankawa, Takuya; Sekine, Yurina

Isotope News, (778), p.34 - 35, 2021/12

A high-performance adsorbent was synthesized by reaction of waste bone and sodium hydrogen carbonate. Since waste bones are inexpensive and well-supplied materials, it has the potential to be used for a wide range of decontamination and removal of harmful metals.

Journal Articles

Sewage sludge ash contaminated with radiocesium; Solidification with alkaline-reacted metakaolinite (geopolymer) and Portland cement

Kozai, Naofumi; Sato, Junya; Osugi, Takeshi; Shimoyama, Iwao; Sekine, Yurina; Sakamoto, Fuminori; Onuki, Toshihiko

Journal of Hazardous Materials, 416, p.125965_1 - 125965_9, 2021/08

 Times Cited Count:16 Percentile:86.11(Engineering, Environmental)

Journal Articles

A Cellulose nanofiber hydrogel prepared via freeze cross-linking

Sekine, Yurina

Kata Gijutsu, 36(8), p.70 - 73, 2021/08

We developed a cross-linking method using freeze concentration and used it to synthesize a cellulose nanofiber hydrogel with high compressive strength. We will introduce the gelation mechanism and properties of the hydrogels in this article.

Journal Articles

Magnetically navigated protein transduction in vivo using iron oxide-nanogel chaperone hybrid

Kawasaki, Riku*; Sasaki, Yoshihiro*; Nishimura, Tomoki*; Katagiri, Kiyofumi*; Morita, Keiichi*; Sekine, Yurina; Sawada, Shinichi*; Mukai, Sadaatsu*; Akiyoshi, Kazunari*

Advanced Healthcare Materials, 10(9), p.2001988_1 - 2001988_8, 2021/05

 Times Cited Count:6 Percentile:62.81(Engineering, Biomedical)

Systems for "protein transduction", the intracellular delivery of functional proteins, are needed to address the deliverability challenges of protein therapy, but protein transfer in vivo remains difficult. In this study, we have developed a magnetically induced in vivo protein transfection system using a magnetic nanogel chaperone (MC) composed of iron oxide nanoparticles and polysaccharide nanogels. Experiments using an oral cancer model have shown that this MC system is useful for cancer treatment.

Journal Articles

Development of spin-contrast-variation neutron powder diffractometry for extracting the structure factor of hydrogen atoms

Miura, Daisuke*; Kumada, Takayuki; Sekine, Yurina; Motokawa, Ryuhei; Nakagawa, Hiroshi; Oba, Yojiro; Ohara, Takashi; Takata, Shinichi; Hiroi, Kosuke; Morikawa, Toshiaki*; et al.

Journal of Applied Crystallography, 54(2), p.454 - 460, 2021/04


 Times Cited Count:1 Percentile:19.03(Chemistry, Multidisciplinary)

We developed a spin-contrast-variation neutron powder diffractometry technique that extracts the structure factor of hydrogen atoms, namely, the contribution of hydrogen atoms to a crystal structure factor. Crystals of L-glutamic acid were dispersed in a dpolystyrene matrix containing 4-methacryloyloxy-2,2,6,6,-tetramethyl-1-piperidinyloxy (TEMPO methacrylate) to polarize their proton spins dynamically. The intensities of the diffraction peaks of the sample changed according to the proton polarization, and the structure factor of the hydrogen atoms was extracted from the proton-polarization dependent intensities. This technique is expected to enable analyses of the structures of hydrogen-containing materials that are difficult to determine with conventional powder diffractometry.

Journal Articles

Carbonated nanohydroxyapatite from bone waste and its potential as a super adsorbent for removal of toxic ions

Sekine, Yurina; Nankawa, Takuya; Yamada, Teppei*; Matsumura, Daiju; Nemoto, Yoshihiro*; Takeguchi, Masaki*; Sugita, Tsuyoshi; Shimoyama, Iwao; Kozai, Naofumi; Morooka, Satoshi

Journal of Environmental Chemical Engineering, 9(2), p.105114_1 - 105114_12, 2021/04

 Times Cited Count:7 Percentile:52.52(Engineering, Environmental)

Remediating toxic ion contamination is crucial for protecting human health and the environment. This study aimed to provide a powerful strategy for effectively utilizing bone waste from the food production and preparation industries for removal of toxic ions. Here, we show that immersing pig bone in NaHCO$$_{3}$$ solution produced a carbonated nanohydroxyapatites (C-NHAP). The C-NHAP exhibited high adsorptivity for Sr$$^{2+}$$, Cd$$^{2+}$$, Pb$$^{2+}$$, and Cu$$^{2+}$$. The strontium adsorptivity was about 250 and 4,500 times higher than that of normal bone and synthetic HAP, respectively. The C-NHAP is an eco-friendly, high-performance material that is simple to prepare and should be useful for tackling problems of food waste disposal and environmental pollution.

Journal Articles

Development of a high-performance toxic metal adsorbent using waste bones

Sekine, Yurina; Nankawa, Takuya

Chem-Station (Internet), 1 Pages, 2021/03

We will explain the experimental results and the background of the research that developed a highly efficient toxic metal adsorbent using wastebone as a raw material.

Journal Articles

Introduction to SANS-J and PNO

Kumada, Takayuki; Motokawa, Ryuhei; Nakagawa, Hiroshi; Oba, Yojiro; Sekine, Yurina

Hamon, 31(1), p.5 - 6, 2021/02

no abstracts in English

84 (Records 1-20 displayed on this page)