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Yunoki S, Mogi A, Mizuno K, Nagakawa Y, Hiraoka Y. Plasticizer-gelatin mixed solutions as skin protection materials with flexible-film-forming capability. Heliyon 2024; 10:e25441. [PMID: 38352760 PMCID: PMC10862670 DOI: 10.1016/j.heliyon.2024.e25441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/18/2024] [Accepted: 01/26/2024] [Indexed: 02/16/2024] Open
Abstract
To demonstrate the feasibility of plasticizer-gelatin solutions as novel skin protection materials from a physical aspect, we evaluated the rheological properties of the solutions and the mechanical properties and textures of their dried sheets and films. Three types of sugars and polyols were employed as organic plasticizers and mixed with gelatin in solutions at plasticizer/gelatin weight ratios of 0.13-1.67. The plasticizers minimally affected the viscosities and gelation temperatures of the gelatin solutions, but they remarkably softened dried gelatin sheets, except for propylene glycol. Glycerol exhibited the best plasticizing effects, but the sheets obtained using glycerol showed tacky textures. Preliminary investigations on the film-forming properties of the solutions on the human skin showed that the fructose-gelatin solution at a weight ratio of 1.0 formed a flexible thin film with a texture and mechanical properties similar to those of a commercially available polyurethane-based flexible film dressing. In terms of physical properties, we conclude that the fructose-gelatin solution has potential as a skin protection material that transforms from a solution to a film on the skin.
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Affiliation(s)
- Shunji Yunoki
- Institute for the Promotion of Business-Regional Collaboration, Hokkaido University, Kita-21, Nishi-11, Kita-ku, Sapporo, Hokkaido, 001-0021, Japan
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute (TIRI), 2-4-10 Aomi, Koto-ku, Tokyo, 135-0064, Japan
| | - Asami Mogi
- New Business Planning and Research Section, Shin Nippon Yakugyo Co., Ltd, 15-10 Nihonbashi-Kodenmacho, Chuo-Ku, Tokyo, 103-0001, Japan
| | - Keizo Mizuno
- New Business Planning and Research Section, Shin Nippon Yakugyo Co., Ltd, 15-10 Nihonbashi-Kodenmacho, Chuo-Ku, Tokyo, 103-0001, Japan
| | - Yoshiyasu Nagakawa
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute (TIRI), 2-4-10 Aomi, Koto-ku, Tokyo, 135-0064, Japan
| | - Yosuke Hiraoka
- Biomedical Department, R&D Center, Nitta Gelatin Inc., 2-22, Futamata, Yao City, Osaka, 581-0024, Japan
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Kohta M, Yunoki S, Sugama J. Effect of prophylactic dressings to reduce pressure injuries: a polymer-based skin model. J Wound Care 2024; 33:S4-S9. [PMID: 38348862 DOI: 10.12968/jowc.2024.33.sup2.s4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
OBJECTIVE This study evaluated the effect of pressure injury (PI) prophylactic dressings used for patients at high risk of PI development to reduce friction, shear force and pressure, and their combined force, in an original polymer-based skin model. METHOD A low-friction outer-layer hydrocolloid (LFH) dressing and a multilayered silicone foam (MSF) dressing were used. Before application, compression and friction properties were measured. Our original experimental model-the 'simulated skin-shearing test'-consisted of: a weight; a polyurethane-based skin model containing a three-axis tactile sensor; dressings; a table covered with bedsheets; and a mechanical tester, by which the interface friction force, internal shear force and pressure were measured continuously during skin model movements. An estimated combined force generated by internal shear and pressure was represented as a vector. A model with no dressing was used as a control. RESULTS The LFH dressing had significantly higher compression strength versus the MSF dressing. In contrast, the dynamic coefficient of friction was lower for the LFH dressing versus the MSF dressing (p<0.05). In simulated skin-shearing test results, shear forces were 0.45N and 0.42N for LFH and MSF dressings, respectively, with no significant difference. The estimated combined force was lower for the MSF dressing compared with that of the LFH dressing and control. CONCLUSION The shear force-reducing effect in the skin model was equivalent between the LFH and MSF dressings. However, the MSF dressing significantly reduced the force generated by a combination of internal shear force and pressure compared with the LFH dressing.
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Affiliation(s)
- Masushi Kohta
- Research Center for Implementation Nursing Science Initiative, School of Health Sciences, Fujita Health University, Aichi, Japan
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Junko Sugama
- Research Center for Implementation Nursing Science Initiative, School of Health Sciences, Fujita Health University, Aichi, Japan
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3
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Hoshiba T, Yunoki S. Comparison of decellularization protocols for cultured cell-derived extracellular matrix-Effects on decellularization efficacy, extracellular matrix retention, and cell functions. J Biomed Mater Res B Appl Biomater 2023; 111:85-94. [PMID: 35852254 DOI: 10.1002/jbm.b.35135] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/08/2022] [Accepted: 07/06/2022] [Indexed: 12/27/2022]
Abstract
The in vitro reconstruction of the extracellular matrix (ECM) is required in tissue engineering and regenerative medicine because the ECM can regulate cell functions in vivo. For ECM reconstruction, a decellularization technique is used. ECM reconstructed by decellularization (dECM) is prepared from tissues/organs and cultured cells. Although decellularization methods have been optimized for tissue-/organ-derived dECM, the methods for cultured cell-derived dECM have not yet been optimized. Here, two physical (osmotic shocks) and five chemical decellularization methods are compared. The decellularization efficacies were changed according to the decellularization methods used. Among them, only the Triton X-100 and Tween 20 treatments could not decellularize completely. Additionally, when the efficacies were compared among different types of cells (monolayered cells with/without strong cell adhesion, multilayered cells), the efficacies were decreased for multilayered cells or cells with strong cell adhesion. Retained ECM contents tended to be greater in the dECM prepared by osmotic shocks than in those prepared by chemical methods. The contents impacted cell adhesion, shapes, growth and intracellular signal activation on the dECM. The comparison would be helpful for the optimization of decellularization methods for cultured cells, and it could also provide new insights into developing milder decellularization methods for tissues and organs.
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Affiliation(s)
- Takashi Hoshiba
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
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Takatori Y, Uraoka T, Sasaki M, Narita T, Yunoki S, Shiraishi J, Yahagi N. Potential of temperature-response collagen-genipin sol as a novel submucosal injection agent for endoscopic resection: Acute and chronic phase study using living animals. Dig Endosc 2022; 35:471-480. [PMID: 36219497 DOI: 10.1111/den.14452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 10/03/2022] [Indexed: 02/08/2023]
Abstract
OBJECTIVES We proposed a novel temperature-response collagen sol as a submucosal injection agent for endoscopic resection (ER) using pepsin-solubilized collagen (PSC) and genipin (Ge) in a prior study. This study aimed to evaluate the usefulness and safety of the sol (PSC/Ge) in acute and chronic phase experiments using living animals. METHODS In experiment 1, we performed endoscopic submucosal dissection (ESD) for six pigs using normal saline (NS), sodium hyaluronate (SH), and PSC/Ge. We compared the required amount of each agent per unit area and procedure time. In experiment 2, we created artificial ulcers with endoscopic mucosal resection (EMR) for five pigs using NS and PSC sol. We compared the artificial ulcer residual rate at 7 and 14 days after EMR, and the scarring rate at 14 days after EMR. RESULTS The required amount of agents per unit area for PSC/Ge (0.8 ± 0.8 mL/cm2 ) and SH (1.1 ± 0.8 mL/cm2 ) were significantly smaller than that for NS (1.8 ± 0.7 mL/cm2 ). The total procedure time did not have a statistical difference. The artificial ulcer residual rates were 47.3 ± 0.7% for NS and 40.3 ± 0.7% for PSC/Ge on day 7 (P = 0.51), and 15.0 ± 0.1% for NS and 10.2 ± 0.1% for PSC/Ge sol on day 14 (P = 0.35). The scarring rate on day 14 was 10% for NS and 20% for PSC/Ge. CONCLUSION We demonstrated the feasibility of a novel temperature-response collagen gel as a submucosal injection agent for ER in the acute and chronic phase animal experiment.
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Affiliation(s)
- Yusaku Takatori
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Tokyo, Japan
| | - Toshio Uraoka
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Gastroenterology and Hepatology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Motoki Sasaki
- Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Tokyo, Japan
| | - Takefumi Narita
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan.,Institute for the Promotion of Business-Regional Collaboration, Hokkaido University, Hokkaido, Japan
| | - Junichi Shiraishi
- Department of Pathology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Naohisa Yahagi
- Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Tokyo, Japan
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Nagakawa Y, Fujita S, Yunoki S, Tsuchiya T, Suye SI, Kinoshita K, Sasaki M, Itoi T. Characterization and preliminary in vivo evaluation of a self-expandable hydrogel stent with anisotropic swelling behavior and endoscopic deliverability for use in biliary drainage. J Mater Chem B 2022; 10:4375-4385. [PMID: 35274668 DOI: 10.1039/d2tb00104g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We demonstrate the potential of a novel self-expandable biliary stent comprised of poly(vinyl alcohol) (PVA) hydrogel with anisotropic swelling behavior and endoscopic deliverability in vivo, using a porcine stent model. The mechanism underlying the anisotropic swelling behavior and endoscopic deliverability (i.e., flexibility) was investigated by scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), evaluation of the water content and swelling ratio, and three-point bending tests. The in vivo experiment using a porcine stent model indicated that the tube-shaped PVA hydrogel could effectively expand the biliary tract, without disturbing bile flow. SEM and SAXS showed that PVA hydrogels prepared by drying under extension showed structural orientation along the extension axis, leading to anisotropic swelling. The water content of the PVA hydrogel was found to be crucial for maintaining flexibility as well as endoscopic deliverability. In conclusion, this study demonstrated the novel concept of using a hydrogel stent as a self-expandable biliary stent.
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Affiliation(s)
- Yoshiyasu Nagakawa
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, 2-4-10, Aomi, Koto-ku, Tokyo, 135-0064, Japan. .,Department of Frontier Fiber Technology and Sciences, Graduate School of Engineering University of Fukui, 3-9-1, Bunkyo, Fukui, 910-8507, Japan.
| | - Satoshi Fujita
- Department of Frontier Fiber Technology and Sciences, Graduate School of Engineering University of Fukui, 3-9-1, Bunkyo, Fukui, 910-8507, Japan. .,Life Science Innovation Center, University of Fukui, 3-9-1, Bunkyo, Fukui, 910-8507, Japan
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, 2-4-10, Aomi, Koto-ku, Tokyo, 135-0064, Japan.
| | - Takayoshi Tsuchiya
- Department of Gastroenterology and Hepatology, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, Japan
| | - Shin-Ichiro Suye
- Department of Frontier Fiber Technology and Sciences, Graduate School of Engineering University of Fukui, 3-9-1, Bunkyo, Fukui, 910-8507, Japan. .,Life Science Innovation Center, University of Fukui, 3-9-1, Bunkyo, Fukui, 910-8507, Japan
| | - Kenji Kinoshita
- Industrial Analysis and Inspection Technology Group, Tokyo Metropolitan Industrial Technology Research Institute, 2-4-10, Aomi, Koto-ku, Tokyo, 135-0064, Japan
| | - Motoki Sasaki
- Division of Research and Development for Minimally Invasive Treatment, Cancer Center Keio University School of Medicine, 35, Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Takao Itoi
- Department of Gastroenterology and Hepatology, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, Japan
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Yunoki S, Hatayama H, Ohyabu Y, Kobayashi K. Fibril matrices created with collagen from the marine fish barramundi for use in conventional three-dimensional cell culture. Int J Biol Macromol 2022; 203:361-368. [PMID: 35074336 DOI: 10.1016/j.ijbiomac.2022.01.098] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 12/21/2021] [Accepted: 01/14/2022] [Indexed: 12/14/2022]
Abstract
Collagen obtained from fish offal (skin, scales, and bones) is required from some religious and ethnic groups, thus indirectly increasing demands for fish collagen for biomedical applications. The limitation of fish collagen is its lower thermal stability compared to mammalian collagen. In this study, we focused on collagen extracted from scales of the marine fish barramundi (Lates calcarifer) and demonstrated the suitability for the collagen to be utilized in collagen fibril matrices (CFM). Collagen was extracted from the scales through pepsin-digestion and purified (designated as "BC"). The denaturation temperature (Td) for BC was determined to be 36.4 °C, one of the highest among fish collagens. BC formed CFM which was thermally stable at 37 °C, while Td was lower than 37 °C. This could be explained by the fast fibril formation, initiating at temperatures near 20 °C in a temperature-elevated process. As a result, the NIH3T3 cells were successfully encapsulated in the CFM of BC and cultured three-dimensionally for 7 d. The cells spread and exhibited well-developed pseudopodia in the CFM of BC as observed in the CFM of pig collagen matrices. This is the first report on fish CFM used for conventional 3-D cell culture.
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Affiliation(s)
- Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute (TIRI), 2-4-10 Aomi, Koto-ku, Tokyo 135-0064, Japan.
| | - Hirosuke Hatayama
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute (TIRI), 2-4-10 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Yoshimi Ohyabu
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute (TIRI), 2-4-10 Aomi, Koto-ku, Tokyo 135-0064, Japan
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7
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Uraoka T, Yunoki S, Sasaki M, Kinoshita S, Takatori Y, Hirai Y, Narita T, Ramberan H, Shimoda M, Yahagi N. Closure of gastric perforations during endoluminal resection using a novel biodegradable collagen sol: A feasibility survival study on porcine model (with video). Dig Endosc 2022; 34:105-112. [PMID: 33615579 DOI: 10.1111/den.13962] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/16/2021] [Indexed: 01/11/2023]
Abstract
OBJECTIVE A prior study using porcine colon demonstrated the feasibility of a novel injectable, temperature?responsive, and biodegradable collagen sol (ICS) that transforms from a liquid to a gel state in response to body temperature for endoscopic closure of perforation during endoscopic resection (ER). This study aims to report the acute and survival outcomes of ICS for gastric perforations during ER. METHODS In two experiments using nine live pigs under general anesthesia, four and six perforations (3-5\xA0mm) were created using an electrosurgical knife in acute and survival experiments, respectively. ICS was delivered to the perforations using an endoscopic catheter. In Experiment 1, a leak test and histopathology were performed on all explanted stomachs after euthanization. In Experiment 2, perforation sites were assessed by gastroscopy and histopathology 7, 14 and 28\xA0days post? RESULTS In Experiment 1, gastroscopy confirmed complete closure of the perforations with ICS and no evidence of leak. Subsequent histopathology revealed a fixation of collagen gel (CG) as a sealant agent at the perforation sites. There were no adverse effects related with ESD or the use of ICS. In Experiment 2, histopathology revealed a fixation of CG as a sealant agent, replacement with granulation tissue and no CG; and fibrotic tissue at 7, 14 and 28\xA0days, respectively. CONCLUSIONS This study presents a novel method using ICS, demonstrating promising efficacy and safety profile for endoscopic closure of perforations during ER. Further studies are necessary before translating to clinical use.
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Affiliation(s)
- Toshio Uraoka
- Department of Gastroenterology and Hepatology, Gunma University Graduate School of Medicine, Gunma, Japan.,Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, Tokyo, Japan.,Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Motoki Sasaki
- Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, Tokyo, Japan
| | - Satoshi Kinoshita
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Yusaku Takatori
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Yuichiro Hirai
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Takefumi Narita
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Hemchand Ramberan
- Program in Endoscopic Oncology and Advanced Endoscopy, Riverside Regional Medical Center, Newport News, USA
| | - Masayuki Shimoda
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan
| | - Naohisa Yahagi
- Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, Tokyo, Japan
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Kawamura T, Yunoki S, Ohyabu Y, Uraoka T, Muramatsu K. Crosslinking Efficacy and Cytotoxicity of Genipin and Its Activated Form Prepared by Warming It in a Phosphate Buffer: A Comparative Study. Materials (Basel) 2021; 14:ma14216600. [PMID: 34772122 PMCID: PMC8585344 DOI: 10.3390/ma14216600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/24/2021] [Accepted: 10/26/2021] [Indexed: 01/14/2023]
Abstract
The aim of the present study was to compare the acute and cumulative cytotoxicity of intact (n-GE) and warmed genipin (w-GE), while investigating the differences in crosslinking capabilities of these two genipins by rheological and mechanical tests. The n-GE solution was prepared by dissolving genipin powder in a sodium phosphate buffer solution. The w-GE solution was prepared by warming the n-GE solution at 37 °C for 24 h. The mechanical tests for chitosan (CH)/genipin gels showed the crosslinking rate of w-GE was much greater than that of n-GE up until 6 h after preparation, whereas the degree of crosslinking of CH/n-GE gels became higher at 12 h. The ISO 10993-5 standard method, which is established specifically for evaluating cumulative cytotoxicity, determined equivalent IC50 for w-GE (0.173 mM) and n-GE (0.166 mM). On the other hand, custom-made cytotoxicity tests using a WST-8 assay after 1 h of cultivation showed that the acute cytotoxicity of w-GE was significantly higher than that of n-GE at concentrations between 0.1–5 mM. The acute cytotoxicity of w-GE should be taken into consideration in its practical uses, despite the fact that the much faster crosslinking of w-GE is useful as an effective cross linker for in-situ forming gels.
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Affiliation(s)
- Takeya Kawamura
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute (TIRI), 2-4-10 Aomi, Koto-ku, Tokyo 135-0064, Japan; (T.K.); (Y.O.)
- School of Science and Engineering, Tokyo Denki University, Ishizaka, Hatoyama-cho, Hiki-gun 350-0394, Japan;
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute (TIRI), 2-4-10 Aomi, Koto-ku, Tokyo 135-0064, Japan; (T.K.); (Y.O.)
- Correspondence:
| | - Yoshimi Ohyabu
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute (TIRI), 2-4-10 Aomi, Koto-ku, Tokyo 135-0064, Japan; (T.K.); (Y.O.)
| | - Toshio Uraoka
- Department of Gastroenterology and Hepatology, Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi 371-8514, Japan;
| | - Kazuaki Muramatsu
- School of Science and Engineering, Tokyo Denki University, Ishizaka, Hatoyama-cho, Hiki-gun 350-0394, Japan;
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Abdelsalam H, Teleb N, Wang B, Yunoki S, Zhang Q. The electronic, adsorption, and catalytic properties of Bi-, Sb-, and As-nanoclusters. Catal Today 2021. [DOI: 10.1016/j.cattod.2020.06.069] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Uraoka T, Yunoki S, Kinoshita S, Takatori Y, Hirai Y, Tanaka H, Narita T, Shimoda M. Novel temperature-responsive, biodegradable and injectable collagen sol for the endoscopic closure of colonic perforation holes: Animal study (with videos). Dig Endosc 2021; 33:616-620. [PMID: 32794223 DOI: 10.1111/den.13810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/07/2020] [Accepted: 08/11/2020] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Endoscopic submucosal dissection (ESD) poses a risk of intraprocedural perforation. We have developed a biodegradable injectable collagen sol that undergoes a liquid-to-gel formation in response to body temperature. Here, we investigated the feasibility of this novel collagen sol for the endoscopic closure of iatrogenic perforation holes. METHODS In two experiments, 12 and 5 colonic perforation holes (3-5 mm) were made using an ESD knife in four and three live pigs under general anesthesia, respectively. In Experiment 1, collagen sol was delivered to the perforation holes using an endoscopic catheter. When the colon was expanded by CO2 insufflation, endo-clips were applied to the perforation holes. For Experiment 2, Collagen sol adjusted based on the Experiment 1 results was delivered to the perforation holes in the same manner. A leak test was performed for every colon after the pigs were killed, and the histology of the perforation sites was evaluated. RESULTS In both experiments, collagen sol was smoothly delivered to the target area and fixed as a gel on the perforation holes. Experiment 1, 83% (10/12) of the perforation holes were completely closed, and all endo-clips were placed with composure. Experiment 2, all perforation holes were completely closed with collagen gel. There was no leak from the perforation holes. Histology revealed a fixation of the collagen gel as an embolus agent in the perforation holes. CONCLUSIONS This novel collagen sol may be used for the endoscopic closure of intraprocedural perforation. Further studies will determine this collagen sol's clinical feasibility and safety.
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Affiliation(s)
- Toshio Uraoka
- Department of Gastroenterology and Hepatology, Gunma University Graduate School of Medicine, Gumma, Japan.,Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Satoshi Kinoshita
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Yusaku Takatori
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Yuichiro Hirai
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Hirohito Tanaka
- Department of Gastroenterology and Hepatology, Gunma University Graduate School of Medicine, Gumma, Japan
| | - Takefumi Narita
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Masayuki Shimoda
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan
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11
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Kobashi H, Yunoki S, Kato N, Shimazaki J, Ide T, Tsubota K. Evaluation of the Physiological Corneal Intrastromal Riboflavin Concentration and the Corneal Elastic Modulus After Violet Light Irradiation. Transl Vis Sci Technol 2021; 10:12. [PMID: 34854915 PMCID: PMC8648052 DOI: 10.1167/tvst.10.5.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose KeraVio is a corneal crosslinking treatment modality that utilizes violet light (VL)-emitting glasses and topical epithelium-on riboflavin administration. We focus on the new KeraVio protocol without riboflavin. This study aims to quantify the physiological intrastromal concentrations of riboflavin in corneas without riboflavin decreases and evaluate the biomechanics of corneas after VL irradiation. Methods Twelve human donor corneas were included in this study and randomly categorized into four groups. The corneas underwent four imbibition techniques (physiological riboflavin without drops, epithelial [epi]-on with 0.05% flavin adenine dinucleotide [FAD], epi-off with FAD, and 0.1% riboflavin epi-off). Corneas in the FAD epi-on, FAD epi-off, and riboflavin epi-off groups were instilled with the respective solution every 2 minutes for 30 minutes. An ex vivo experiment was conducted with 24 porcine corneas arranged into three treatment groups and one control group. Corneas in the KeraVio with FAD epi-on group were treated with VL irradiation at 0.31 mW/cm2 for 4.8 hours (5.4 J/cm2) and simultaneously received FAD drops every 30 minutes during the VL irradiation. Corneas in the group with KeraVio without FAD epi-on were only treated with VL irradiation (5.4 J/cm2). Results We identified the original physiological riboflavin of human corneal stroma at a concentration of 0.31 ± 0.03 µg/g, but its value was approximately 39-fold smaller than that in the 0.1% riboflavin epi-off group. The group with KeraVio without FAD and the standard corneal crosslinking group showed a significant increase in biomechanical stability compared with the controls, whereas the elastic modulus in the treated groups was equivalent. Conclusions We preliminarily identified physiological riboflavin in human corneas without adding riboflavin drops. The VL exposure may strengthen the corneal biomechanics without requiring the use of additional riboflavin drops. Translational Relevance We preliminarily identified physiological riboflavin in the human cornea without adding riboflavin drops. VL irradiation without riboflavin drops may increase the corneal stiffness using physiological riboflavin.
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Affiliation(s)
- Hidenaga Kobashi
- Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan.,Tsubota Laboratory Inc., Tokyo, Japan
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Naoko Kato
- Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan.,Department of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
| | - Jun Shimazaki
- Department of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
| | | | - Kazuo Tsubota
- Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan.,Tsubota Laboratory Inc., Tokyo, Japan
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13
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Abdelsalam H, O. Younis W, Saroka VA, Teleb NH, Yunoki S, Zhang Q. Interaction of hydrated metals with chemically modified hexagonal boron nitride quantum dots: wastewater treatment and water splitting. Phys Chem Chem Phys 2020; 22:2566-2579. [DOI: 10.1039/c9cp06823f] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The electronic and adsorption properties of chemically modified square hexagonal boron nitride quantum dots are investigated using density functional theory calculations.
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Affiliation(s)
- H. Abdelsalam
- School of Materials Science and Engineering
- Yancheng Institute of Technology
- Yancheng 224051
- P. R. China
- Theoretical Physics Department
| | - W. O. Younis
- Vice Presidency for Postgraduate Studies and Scientific Research
- Imam Abdulrahman Bin Faisal University
- Dammam
- Saudi Arabia
| | - V. A. Saroka
- Institute for Nuclear Problems
- Belarusian State University
- 220030 Minsk
- Belarus
- Center for Quantum Spintronics
| | - N. H. Teleb
- Electron Microscope and Thin Films Department
- National Research Centre
- Giza
- Egypt
| | - S. Yunoki
- Computational Condensed Matter Physics Laboratory
- RIKEN
- Wako
- Japan
| | - Q. Zhang
- School of Materials Science and Engineering
- Yancheng Institute of Technology
- Yancheng 224051
- P. R. China
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14
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Nagakawa Y, Fujita S, Yunoki S, Tsuchiya T, Suye S, Itoi T. Self‐expandable hydrogel biliary stent design utilizing the swelling property of poly(vinyl alcohol) hydrogel. J Appl Polym Sci 2019. [DOI: 10.1002/app.48851] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Yoshiyasu Nagakawa
- Biotechnology GroupTokyo Metropolitan Industrial Technology Research Institute 2‐4‐10, Aomi, Koto‐ku Tokyo 135‐0064 Japan
- Department of Frontier Fiber Technology and SciencesGraduate School of Engineering, University of Fukui 3‐9‐1, Bunkyo Fukui 910‐8507 Japan
| | - Satoshi Fujita
- Department of Frontier Fiber Technology and SciencesGraduate School of Engineering, University of Fukui 3‐9‐1, Bunkyo Fukui 910‐8507 Japan
- Life Science Innovation CenterUniversity of Fukui 3‐9‐1, Bunkyo Fukui 910‐8507 Japan
| | - Shunji Yunoki
- Biotechnology GroupTokyo Metropolitan Industrial Technology Research Institute 2‐4‐10, Aomi, Koto‐ku Tokyo 135‐0064 Japan
| | - Takayoshi Tsuchiya
- Department of Gastroenterology and HepatologyTokyo Medical University 6‐7‐1, Nishishinjuku, Shinjuku‐ku Tokyo 160‐0023 Japan
| | - Shin‐ichiro Suye
- Department of Frontier Fiber Technology and SciencesGraduate School of Engineering, University of Fukui 3‐9‐1, Bunkyo Fukui 910‐8507 Japan
- Life Science Innovation CenterUniversity of Fukui 3‐9‐1, Bunkyo Fukui 910‐8507 Japan
| | - Takao Itoi
- Department of Gastroenterology and HepatologyTokyo Medical University 6‐7‐1, Nishishinjuku, Shinjuku‐ku Tokyo 160‐0023 Japan
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15
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Takatori Y, Uraoka T, Narita T, Yunoki S, Yahagi N. Potential of temperature-response collagen-genipin sols as a novel submucosal injection material for endoscopic resection. Endosc Int Open 2019; 7:E561-E567. [PMID: 30957006 PMCID: PMC6449160 DOI: 10.1055/a-0867-9450] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 02/14/2019] [Indexed: 01/14/2023] Open
Abstract
Background and study aims We developed a novel submucosal (SM) injection material that contained pepsin-solubilized collagen (PSC), genipin (Ge) and phosphate buffer (PB). The aim of this study was to validate safety and usability of it for endoscopic resection (ER). Materials and methods In preliminary studies, 1) appropriate warming time and concentration of Ge, and concentration of NaCl in PB, 2) storage modulus of PSC, Ge, and PB mixture (PSC/Ge), and PSC as a mechanical property, 3) histological finding after injection, and histological toxicity of PSC/Ge was evaluated. We injected PSC/Ge, PSC, sodium hyaluronate (SH), dextrose (DW), and normal saline (NS) into SM of resected porcine stomach. We compared mean height of mucosal elevation after immediate injection (MH) and mean retaining rate at 60 minutes (MR) as ex vivo study. Results Optimal condition of PSC/Ge was Ge 5.5 mMol with 24 hours worming time and NaCl 280 mMol. PSC/Ge had better mechanical property than PSC. It was efficiently integrated and confined to the SM with acceptable toxicity. MH of PSC/Ge (5.1 ± 0.74 mm) and PSC (4.8 ± 0.84 mm) were significantly higher than NS (3.2 ± 0.84 mm). MR of PSC/Ge (100 ± 0.0%) was significantly higher than NS (61.7 ± 11.2%), DW (58.3 ± 11.8%) and SH (61.8 ± 8.6%). Conclusion PSC/Ge and PSC has potential to be safe and usable for ER. PSC/Ge was better than PSC because of better mechanical property than PSC.
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Affiliation(s)
- Yusaku Takatori
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan,Department of Gastroenterology, National Hospital Organization Saitama Hospital, Saitama, Japan,Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Tokyo, Japan
| | - Toshio Uraoka
- Department of Gastroenterology and Hepatology, Gunma University School of Medicine, Gunma, Japan,Corresponding author Toshio Uraoka, MD, PhD Department of Gastroenterology and HepatologyGunma University School of Medicine3-39-22, Showa-machi, Maebashi-shiGunma, 371-8511Japan+81-27-220-7798
| | - Takefumi Narita
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Naohisa Yahagi
- Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Tokyo, Japan
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16
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Meng D, Tanaka H, Kobayashi T, Hatayama H, Zhang X, Ura K, Yunoki S, Takagi Y. The effect of alkaline pretreatment on the biochemical characteristics and fibril-forming abilities of types I and II collagen extracted from bester sturgeon by-products. Int J Biol Macromol 2019; 131:572-580. [PMID: 30880060 DOI: 10.1016/j.ijbiomac.2019.03.091] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 03/11/2019] [Accepted: 03/14/2019] [Indexed: 11/18/2022]
Abstract
Non-mammalian collagens have attracted increasing attention for industrial and biomedical use. We have therefore evaluated extraction conditions and the biochemical properties of collagens from aquacultured sturgeon. Pepsin-soluble type I and type II collagen were respectively extracted from the skin and notochord of bester sturgeon by-products, with yields of 63.9 ± 0.19% and 35.5 ± 0.68%. Collagen extraction efficiency was improved by an alkaline pretreatment of the skin and notochord (fewer extraction cycles were required), but the final yields decreased to 56.2 ± 0.84% for type I and 31.8 ± 1.13% for type II. Alkaline pretreatment did not affect the thermal stability or triple-helical structure of both types of collagen. Types I and II collagen formed re-assembled fibril structures in vitro, under different conditions. Alkaline pretreatment slowed down the formation of type I collagen fibrils and specifically inhibited the formation of thick fibril-bundle structures. In contrast, alkaline pretreatment did not change type II collagen fibril formation. In conclusion, alkaline pretreatment of sturgeon skin and notochord is an effective method to accelerate collagen extraction process of types I and II collagen without changing their biochemical properties. However, it decreases the yield of both collagens and specifically changes the fibril-forming ability of type I collagen.
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Affiliation(s)
- Dawei Meng
- Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan.
| | - Hiroyuki Tanaka
- Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan.
| | - Taishi Kobayashi
- Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan
| | - Hirosuke Hatayama
- Tokyo Metropolitan Industrial Technology Research Institute, Tokyo 135-0064, Japan.
| | - Xi Zhang
- Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan; College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China.
| | - Kazuhiro Ura
- Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan.
| | - Shunji Yunoki
- Tokyo Metropolitan Industrial Technology Research Institute, Tokyo 135-0064, Japan.
| | - Yasuaki Takagi
- Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan.
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17
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Tonozuka R, Yunoki S, Itoi T, Sofuni A, Tsuchiya T, Ishii K, Tanaka R, Honjo M, Mukai S, Fujita M, Yamamoto K, Asai Y, Matsunami Y, Kurosawa T, Kojima H, Nagakawa Y, Nagakawa Y. Ex vivo assessment of anchoring force of covered biflanged metal stent and covered self-expandable metal stent for interventional endoscopic ultrasound. J Gastroenterol Hepatol 2019; 34:194-201. [PMID: 29871029 DOI: 10.1111/jgh.14307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/08/2018] [Accepted: 05/29/2018] [Indexed: 12/09/2022]
Abstract
BACKGROUND AND AIMS Endoscopic ultrasound (EUS)-guided transmural drainage using a covered biflanged metal stent (CBFMS) and a conventional tubular biliary covered self-expandable metal stent (CSEMS) has recently been performed by EUS experts. However, appropriate traction force of the sheath to prevent the migration during stent deployment is well unknown. Herein, we assessed the anchoring force (AF) of the distal flange in CBFMSs and CSEMSs. METHODS The AFs of four CBFMSs (Stents AX, NG, PL, and SX) and six CSEMSs (Stents BF, BP, EG, HN, SP, and WF) were compared in an ex vivo setting. We assessed the AF produced by each stent using an EUS-guided transmural drainage model and an EUS-guided hepaticogastrostomy model consisting of sheet-shaped specimens of the stomach, gelatin gel, and gelatin tubes. RESULTS For CBFMSs, the maximum AF of Stent AX was significantly higher than those of Stents PL and SX (P < 0.05) in the porcine model. In the gelatin series, all stents except Stent NG showed a nearly similar AF. For CSEMSs, Stents HN, EG, BF, and WF showed gradual AF elevation in the porcine stomach. Stents SP and BP showed a lower AF than the other four stents. For the gelatin setting, the maximum AF of Stents HN, EG, and WF was higher than those of the other stents regardless of the type of specimens. CONCLUSIONS The significance of the AF and traction distance according to the property of various CBFMSs and CSEMSs could be elucidated using ex vivo models.
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Affiliation(s)
- Ryosuke Tonozuka
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Shunji Yunoki
- Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Takao Itoi
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Atsushi Sofuni
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Takayoshi Tsuchiya
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Kentaro Ishii
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Reina Tanaka
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Mitsuyoshi Honjo
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Shuntaro Mukai
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Mitsuru Fujita
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Kenjiro Yamamoto
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Yasutsugu Asai
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Yukitoshi Matsunami
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Takashi Kurosawa
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Hiroyuki Kojima
- Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
| | - Yuichi Nagakawa
- Department of Gastrointestinal and Pediatric Surgery, Tokyo Medical University, Tokyo, Japan
| | - Yoshiyasu Nagakawa
- Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
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18
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Yunoki S, Sugimoto K, Ohyabu Y, Ida H, Hiraoka Y. Accurate and Precise Viscosity Measurements of Gelatin Solutions Using a Rotational Rheometer. FSTR 2019. [DOI: 10.3136/fstr.25.217] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute
| | - Kiyoji Sugimoto
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute
| | - Yoshimi Ohyabu
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute
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Yunoki S, Hatayama H, Ebisawa M, Kondo E, Yasuda K. A novel method for continuous formation of cord‐like collagen gels to fabricate durable fibers in which collagen fibrils are longitudinally aligned. J Biomed Mater Res B Appl Biomater 2018; 107:1011-1023. [DOI: 10.1002/jbm.b.34194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/25/2018] [Accepted: 06/27/2018] [Indexed: 01/23/2023]
Affiliation(s)
- Shunji Yunoki
- Biotechnology GroupTokyo Metropolitan Industrial Technology Research Institute (TIRI) Tokyo Japan
| | - Hirosuke Hatayama
- Biotechnology GroupTokyo Metropolitan Industrial Technology Research Institute (TIRI) Tokyo Japan
| | - Mizue Ebisawa
- Optical Radiation and Acoustics Technology GroupTokyo Metropolitan Industrial Technology Research Institute (TIRI) Tokyo Japan
| | - Eiji Kondo
- Department of Advanced Therapeutic Research for Sports MedicineHokkaido University Graduate School of Medicine Sapporo Japan
| | - Kazunori Yasuda
- Department of Sports MedicineHokkaido University Graduate School of Medicine Sapporo Japan
- Knee Research Center, Yagi Orthopaedic Hospital Sapporo Japan
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20
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Narita T, Yunoki S, Ohyabu Y, Yahagi N, Uraoka T. In situ gelation properties of a collagen-genipin sol with a potential for the treatment of gastrointestinal ulcers. Med Devices (Auckl) 2016; 9:429-439. [PMID: 28008290 PMCID: PMC5170602 DOI: 10.2147/mder.s116633] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We investigated the potential of collagen-genipin sols as biomaterials for treating artificial ulcers following endoscopic submucosal dissection. Collagen sol viscosity increased with condensation, allowing retention on tilted ulcers before gelation and resulting in collagen gel deposition on whole ulcers. The 1.44% collagen sols containing genipin as a crosslinker retained sol fluidity at 23°C for >20 min, facilitating endoscopic use. Collagen sols formed gel depositions on artificial ulcers in response to body temperature, and high temperature responsiveness of gelation because of increased neutral phosphate buffer concentration allowed for thick gel deposition on tilted ulcers. Finally, histological observations showed infiltration of gels into submucosal layers. Taken together, the present data show that genipin-induced crosslinking significantly improves the mechanical properties of collagen gels even at low genipin concentrations of 0.2-1 mM, warranting the use of in situ gelling collagen-genipin sols for endoscopic treatments of gastrointestinal ulcers.
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Affiliation(s)
- Takefumi Narita
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Koto-ku
| | - Shunji Yunoki
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Koto-ku
| | - Yoshimi Ohyabu
- Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Koto-ku
| | - Naohisa Yahagi
- Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Shinjuku-ku
| | - Toshio Uraoka
- Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Meguro-ku, Tokyo, Japan
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21
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Cui Q, Cheng JG, Fan W, Taylor AE, Calder S, McGuire MA, Yan JQ, Meyers D, Li X, Cai YQ, Jiao YY, Choi Y, Haskel D, Gotou H, Uwatoko Y, Chakhalian J, Christianson AD, Yunoki S, Goodenough JB, Zhou JS. Slater Insulator in Iridate Perovskites with Strong Spin-Orbit Coupling. Phys Rev Lett 2016; 117:176603. [PMID: 27824456 DOI: 10.1103/physrevlett.117.176603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Indexed: 06/06/2023]
Abstract
The perovskite SrIrO_{3} is an exotic narrow-band metal owing to a confluence of the strengths of the spin-orbit coupling (SOC) and the electron-electron correlations. It has been proposed that topological and magnetic insulating phases can be achieved by tuning the SOC, Hubbard interactions, and/or lattice symmetry. Here, we report that the substitution of nonmagnetic, isovalent Sn^{4+} for Ir^{4+} in the SrIr_{1-x}Sn_{x}O_{3} perovskites synthesized under high pressure leads to a metal-insulator transition to an antiferromagnetic (AF) phase at T_{N}≥225 K. The continuous change of the cell volume as detected by x-ray diffraction and the λ-shape transition of the specific heat on cooling through T_{N} demonstrate that the metal-insulator transition is of second order. Neutron powder diffraction results indicate that the Sn substitution enlarges an octahedral-site distortion that reduces the SOC relative to the spin-spin exchange interaction and results in the type-G AF spin ordering below T_{N}. Measurement of high-temperature magnetic susceptibility shows the evolution of magnetic coupling in the paramagnetic phase typical of weak itinerant-electron magnetism in the Sn-substituted samples. A reduced structural symmetry in the magnetically ordered phase leads to an electron gap opening at the Brillouin zone boundary below T_{N} in the same way as proposed by Slater.
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Affiliation(s)
- Q Cui
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J-G Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
| | - W Fan
- Computational Condensed Matter Physical Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - A E Taylor
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Tennessee 37831, USA
| | - S Calder
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Tennessee 37831, USA
| | - M A McGuire
- Materials Science and Technology Division, Oak Ridge National Laboratory, Tennessee 37831, USA
| | - J-Q Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - D Meyers
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - X Li
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
| | - Y Q Cai
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
| | - Y Y Jiao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Y Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - H Gotou
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581, Japan
| | - Y Uwatoko
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581, Japan
| | - J Chakhalian
- Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - A D Christianson
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Tennessee 37831, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - S Yunoki
- Computational Condensed Matter Physical Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
- Computational Materials Science Research Team, RIKEN Advanced Institute for Computational Science (AICS), Kobe, Hyogo 650-0047, Japan
- Computational Quantum Matter Research Team, RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - J B Goodenough
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
| | - J-S Zhou
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
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22
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Yunoki S, Hatayama H, Ebisawa M, Kondo E, Yasuda K. A novel fabrication method to create a thick collagen bundle composed of uniaxially aligned fibrils: An essential technology for the development of artificial tendon/ligament matrices. J Biomed Mater Res A 2015; 103:3054-65. [DOI: 10.1002/jbm.a.35440] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Revised: 02/15/2015] [Accepted: 02/23/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Shunji Yunoki
- Biotechnology Group; Tokyo Metropolitan Industrial Technology Research Institute (TIRI); Koto-Ku Tokyo 135-0064 Japan
| | - Hirosuke Hatayama
- Biotechnology Group; Tokyo Metropolitan Industrial Technology Research Institute (TIRI); Koto-Ku Tokyo 135-0064 Japan
| | - Mizue Ebisawa
- Optical Radiation and Acoustics Technology Group; Tokyo Metropolitan Industrial Technology Research Institute (TIRI); Koto-Ku Tokyo 135-0064 Japan
| | - Eiji Kondo
- Department of Advanced Therapeutic Research for Sports Medicine; Hokkaido University Graduate School of Medicine; Kita-Ku Sapporo 060-8638 Japan
| | - Kazunori Yasuda
- Department of Sports Medicine and Joint Surgery; Hokkaido University Graduate School of Medicine; Kita-Ku Sapporo 060-8638 Japan
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23
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Yunoki S, Kohta M, Ohyabu Y, Iwasaki T. In vitro parallel evaluation of antibacterial activity and cytotoxicity of commercially available silver-containing wound dressings. CWCMR 2015. [DOI: 10.2147/cwcmr.s72101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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24
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Ohyabu Y, Hatayama H, Yunoki S. Evaluation of gelatin hydrogel as a potential carrier for cell transportation. J Biosci Bioeng 2014; 118:112-5. [DOI: 10.1016/j.jbiosc.2013.12.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 11/05/2013] [Accepted: 12/06/2013] [Indexed: 11/25/2022]
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Yunoki S, Kohta M, Ohyabu Y, Sekiguchi M, Kubo T, Iwasaki T. Electrostatic immobilization of cetylpyridinium chloride to poly(vinyl alcohol) hydrogels for the simple fabrication of wound dressings with the suppressed release of antibacterial agents. J Appl Polym Sci 2014. [DOI: 10.1002/app.40456] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Shunji Yunoki
- Biotechnology Group; Tokyo Metropolitan Industrial Technology Research Institute 2-4-10, Aomi; Koto-Ku Tokyo 135-0064 Japan
| | - Masushi Kohta
- Medical Engineering Laboratory; ALCARE Company, Limited; 1-21-10 Kyoshima Sumida-Ku Tokyo 131-0046 Japan
| | - Yoshimi Ohyabu
- Biotechnology Group; Tokyo Metropolitan Industrial Technology Research Institute 2-4-10, Aomi; Koto-Ku Tokyo 135-0064 Japan
| | - Masayuki Sekiguchi
- Biotechnology Group; Tokyo Metropolitan Industrial Technology Research Institute 2-4-10, Aomi; Koto-Ku Tokyo 135-0064 Japan
| | - Takabumi Kubo
- Medical Engineering Laboratory; ALCARE Company, Limited; 1-21-10 Kyoshima Sumida-Ku Tokyo 131-0046 Japan
| | - Tetsuji Iwasaki
- Medical Engineering Laboratory; ALCARE Company, Limited; 1-21-10 Kyoshima Sumida-Ku Tokyo 131-0046 Japan
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Annadi A, Zhang Q, Renshaw Wang X, Tuzla N, Gopinadhan K, Lü WM, Roy Barman A, Liu ZQ, Srivastava A, Saha S, Zhao YL, Zeng SW, Dhar S, Olsson E, Gu B, Yunoki S, Maekawa S, Hilgenkamp H, Venkatesan T, Ariando. Anisotropic two-dimensional electron gas at the LaAlO₃/SrTiO₃ (110) interface. Nat Commun 2013; 4:1838. [PMID: 23673623 PMCID: PMC3674248 DOI: 10.1038/ncomms2804] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 03/25/2013] [Indexed: 11/15/2022] Open
Abstract
The observation of a high-mobility two-dimensional electron gas between two insulating complex oxides, especially LaAlO3/SrTiO3, has enhanced the potential of oxides for electronics. The occurrence of this conductivity is believed to be driven by polarization discontinuity, leading to an electronic reconstruction. In this scenario, the crystal orientation has an important role and no conductivity would be expected, for example, for the interface between LaAlO3 and (110)-oriented SrTiO3, which should not have a polarization discontinuity. Here we report the observation of unexpected conductivity at the LaAlO3/SrTiO3 interface prepared on (110)-oriented SrTiO3, with a LaAlO3-layer thickness-dependent metal-insulator transition. Density functional theory calculation reveals that electronic reconstruction, and thus conductivity, is still possible at this (110) interface by considering the energetically favourable (110) interface structure, that is, buckled TiO2/LaO, in which the polarization discontinuity is still present. The conductivity was further found to be strongly anisotropic along the different crystallographic directions with potential for anisotropic superconductivity and magnetism, leading to possible new physics and applications. Although LaAlO3 and SrTiO3 are both insulators, when they are brought together at a (100) interface, a highly conducting two-dimensional electron gas forms between them. Annandi et al. show that this also happens at a (110) interface, counter to expectations that it should not.
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Affiliation(s)
- A Annadi
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
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Hikino S, Yunoki S. Long-range spin current driven by superconducting phase difference in a josephson junction with double layer ferromagnets. Phys Rev Lett 2013; 110:237003. [PMID: 25167525 DOI: 10.1103/physrevlett.110.237003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Indexed: 06/03/2023]
Abstract
We theoretically study spin current through ferromagnet (F) in a Josephson junction composed of s-wave superconductors and two layers of ferromagnets. Using quasiclassical theory, we show that the long-range spin current can be driven by the superconducting phase difference without a voltage drop. The origin of this spin current is due to spin-triplet Cooper pairs (STCs) formed by electrons of equal spin, which are induced by the proximity effect inside the F. We find that the spin current carried by the STCs exhibits long-range propagation in the F even where the Josephson charge current is practically zero. We also show that this spin current persists over a remarkably longer distance than the ordinary spin current carried by spin polarized conduction electrons in the F. Our results thus indicate the promising potential of Josephson junctions based on multilayer ferromagnets for spintronics applications with long-range propagating spin current.
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Affiliation(s)
- S Hikino
- Computational Condensed Matter Physics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan and CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - S Yunoki
- Computational Condensed Matter Physics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan and CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan and Computational Materials Science Research Team, RIKEN AICS, Kobe, Hyogo 650-0047, Japan and Computational Quantum Matter Research Team, RIKEN CEMS, Wako, Saitama 351-0198, Japan
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Ikeda-Fukazawa T, Ikeda N, Tabata M, Hattori M, Aizawa M, Yunoki S, Sekine Y. Effects of crosslinker density on the polymer network structure in poly-N
,N
-dimethylacrylamide hydrogels. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/polb.23305] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | - Naohiro Ikeda
- Department of Applied Chemistry; Meiji University; Kawasaki 214-8571 Japan
| | - Mayu Tabata
- Department of Applied Chemistry; Meiji University; Kawasaki 214-8571 Japan
| | - Masataka Hattori
- Department of Applied Chemistry; Meiji University; Kawasaki 214-8571 Japan
| | - Mamoru Aizawa
- Department of Applied Chemistry; Meiji University; Kawasaki 214-8571 Japan
| | - Shunji Yunoki
- Tokyo Metropolitan Industrial Technology Research Institute; Tokyo 135-0064 Japan
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Yunoki S, Sugiura H, Ikoma T, Kondo E, Yasuda K, Tanaka J. Effects of increased collagen-matrix density on the mechanical properties and in vivo absorbability of hydroxyapatite-collagen composites as artificial bone materials. Biomed Mater 2011; 6:015012. [PMID: 21242631 DOI: 10.1088/1748-6041/6/1/015012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The aim of this study was to evaluate the effects of increased collagen-matrix density on the mechanical properties and in vivo absorbability of porous hydroxyapatite (HAp)-collagen composites as artificial bone materials. Seven types of porous HAp-collagen composites were prepared from HAp nanocrystals and dense collagen fibrils. Their densities and HAp/collagen weight ratios ranged from 122 to 331 mg cm⁻³ and from 20/80 to 80/20, respectively. The flexural modulus and strength increased with an increase in density, reaching 2.46 ± 0.48 and 0.651 ± 0.103 MPa, respectively. The porous composites with a higher collagen-matrix density exhibited much higher mechanical properties at the same densities, suggesting that increasing the collagen-matrix density is an effective way of improving the mechanical properties. It was also suggested that other structural factors in addition to collagen-matrix density are required to achieve bone-like mechanical properties. The in vivo absorbability of the composites was investigated in bone defects of rabbit femurs, demonstrating that the absorption rate decreased with increases in the composite density. An exhaustive increase in density is probably limited by decreases in absorbability as artificial bones.
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Affiliation(s)
- Shunji Yunoki
- Tokyo Metropolitan Industrial Technology Research Institute, Setagaya-ku, Japan.
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30
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Yunoki S, Saito M. A simple method to determine bioethanol content in gasoline using two-step extraction and liquid scintillation counting. Bioresour Technol 2009; 100:6125-6128. [PMID: 19577920 DOI: 10.1016/j.biortech.2009.06.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 06/06/2009] [Accepted: 06/09/2009] [Indexed: 05/28/2023]
Abstract
A simple method for determining bioethanol content in gasoline containing bioethanol (denoted as E-gasoline in this study) is urgently required. Liquid scintillation counting (LSC) was employed based on the principle that (14)C exists in bioethanol but not in synthetic ethanol. Bioethanol was extracted in two steps by water from E-gasoline containing 3% (E3) or 10% (E10) bioethanol. The (14)C radioactivity was measured by LSC and converted to the amount of bioethanol. The bioethanol content in E-gasoline was determined precisely from the partition coefficient in the extraction and the amount of bioethanol in the water phases: 2.98+/-0.10% for E3 and 10.0+/-0.1% for E10 (means+/-SD; n=3). It appears that this method can be used to determine bioethanol content in E-gasoline quickly and easily.
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Affiliation(s)
- Shunji Yunoki
- Life Science Group, Tokyo Metropolitan Industrial Technology Research Institute, 2-11-1 Fukasawa, Setagaya-ku, Tokyo 158-0081, Japan
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31
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Sugiura H, Yunoki S, Kondo E, Ikoma T, Tanaka J, Yasuda K. In vivo biological responses and bioresorption of tilapia scale collagen as a potential biomaterial. J Biomater Sci Polym Ed 2009; 20:1353-68. [PMID: 19622276 DOI: 10.1163/092050609x12457418396658] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To date, collagen for biomedical uses has been obtained from mammalian sources. The purpose of this study was to evaluate the in vivo biological responses and bioresorption of collagen obtained from tilapia (Oreochromis niloticas) scales as compared to those of collagen from porcine dermis. Collagen sponges with micro-porous structures were fabricated from reconstituted collagen fibrils using freeze-drying and cross-linked by dehydrothermal treatment (DHT treatment) or additional treatment with a water-soluble carbodiimide (WSC treatment). The mechanical properties of the tilapia collagen sponges were similar to those of porcine collagen sponges with the same cross-linking methods, where WSC treatment remarkably improved the properties over DHT treatment alone. The pellet implantation tests into the paravertebral muscle of rabbits demonstrated that tilapia collagen caused rare inflammatory responses at 1- and 4-week implantations, statistically similar to those of porcine collagen and a high-density polyethylene as a negative control. The bioresorption rates of both the collagen implants were similar, except for the DHT-treated tilapia collagen sponges at 1-week implantation. These results suggest that tilapia collagen is a potential alternative to conventional mammalian collagens in biomedical uses.
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Affiliation(s)
- Hiroaki Sugiura
- Department of Sports Medicine and Joint Reconstruction Surgery, Hokkaido University, Kita-15 Nishi-7, Sapporo, Hokkaido 060-8638, Japan
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González I, Okamoto S, Yunoki S, Moreo A, Dagotto E. Charge transfer in heterostructures of strongly correlated materials. J Phys Condens Matter 2008; 20:264002. [PMID: 21694336 DOI: 10.1088/0953-8984/20/26/264002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this work, recent theoretical investigations by the authors in the area of oxide multilayers are briefly reviewed. The calculations were carried out using model Hamiltonians and a variety of non-perturbative techniques. Moreover, new results are also included here. They correspond to the generation of a metallic state by mixing insulators in a multilayer geometry, using the Hubbard and double-exchange models. For the latter, the resulting metallic state is also ferromagnetic. This illustrates how electron or hole doping via transfer of charge in multilayers can lead to the study of phase diagrams of transition metal oxides in the clean limit. Currently, these phase diagrams are much affected by the disordering standard chemical doping procedure, which introduces quenched disorder in the material.
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Affiliation(s)
- I González
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN 37996, USA. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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Yunoki S, Matsuda T. Simultaneous Processing of Fibril Formation and Cross-Linking Improves Mechanical Properties of Collagen. Biomacromolecules 2008; 9:879-85. [DOI: 10.1021/bm7012058] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shunji Yunoki
- Genome Biotechnology Laboratory, Kanazawa Institute of Technology, Yatsukaho 3-1, Hakusan City, Ishikawa 924-0838, Japan
| | - Takehisa Matsuda
- Genome Biotechnology Laboratory, Kanazawa Institute of Technology, Yatsukaho 3-1, Hakusan City, Ishikawa 924-0838, Japan
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Yunoki S, Marukawa E, Ikoma T, Sotome S, Fan H, Zhang X, Shinomiya K, Tanaka J. Effect of collagen fibril formation on bioresorbability of hydroxyapatite/collagen composites. J Mater Sci Mater Med 2007; 18:2179-83. [PMID: 17701316 DOI: 10.1007/s10856-007-3011-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2006] [Accepted: 03/22/2007] [Indexed: 05/16/2023]
Abstract
Porous hydroxyapatite/collagen (HAp/Col) composite is a promising biomaterial and a scaffold for bone tissue engineering. The effect of fibril formation of Col in the porous composite on bioresorbability and mechanical strength was investigated. The fibril formation, in mixing a self-organized HAp/Col nanocomposite and sodium phosphate buffer at a neutral condition, occurred during incubation at 37 degrees C, resulting in gelation of the mixture. The porous composites with and without the incubation were obtained by freeze-drying technique, in which macroscopic open pores were formed. The compressive strength of the porous composite with the incubation (34.1 +/- 1.6 kPa) was significantly higher than that without the incubation (28.0 +/- 3.3 kPa) due to the fibril formation of Col. The implantations of the porous composites treated with a dehydrothermal treatment in bone holes revealed that bioresorption was clearly depended on the fibril formation. The bioresorbability in vivo was almost matched to the in vitro test using enzymatic reaction of collagenase.
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Affiliation(s)
- Shunji Yunoki
- Biomaterial Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
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35
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Nagai N, Mori K, Satoh Y, Takahashi N, Yunoki S, Tajima K, Munekata M. In vitro growth and differentiated activities of human periodontal ligament fibroblasts cultured on salmon collagen gel. J Biomed Mater Res A 2007; 82:395-402. [PMID: 17295232 DOI: 10.1002/jbm.a.31110] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Marine-derived collagen is expected to be a much safer alternative to calf collagen, which in medical applications carries the risk of bovine spongiform encephalopathy. In this study, acid-soluble collagen was extracted from salmon skin and crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide during fibril formation to produce a crosslinked salmon collagen (SC) gel. The growth rates and the differentiated functions of human periodontal ligament fibroblasts (HPdLFs) cultured on the SC gel were investigated. Growth was faster on the SC gel than on porcine collagen (PC) gel. In addition, the HPdLFs cultured on the SC gel exhibited higher alkaline phosphatase (ALP) activity than those cultured on the PC gel. Quantitative RT-PCR revealed higher mRNA expression of type I collagen, ALP, and osteocalcin in the HPdLFs cultured on the SC gel. HPdLFs had a flat shape on the SC gel and a spindle shape on the PC gel, as revealed by observation with scanning electron microscopy and immunostaining with cytoskeletal protein and vinculin. The results showed that HPdLFs could grow and show highly differentiated activity on the SC gel as well as on the PC gel.
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Affiliation(s)
- Nobuhiro Nagai
- Creative Research Initiative "Sousei" (CRIS), Hokkaido University, N21-W10, Kita-ku, Sapporo, Hokkaido 001-0021, Japan.
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36
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Yunoki S, Ikoma T, Monkawa A, Marukawa E, Sotome S, Shinomiya K, Tanaka J. Three-dimensional porous hydroxyapatite/collagen composite with rubber-like elasticity. J Biomater Sci Polym Ed 2007; 18:393-409. [PMID: 17540116 DOI: 10.1163/156856207780425077] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A three-dimensional porous hydroxyapatite/collagen (HAp/Col) composite with a random pore structure was fabricated using freeze-drying processes; the self-organized HAp/Col nanocomposite with a weight ratio of 80.5:19.5, freeze-dried, was kneaded in 100 mM sodium phosphate buffer, frozen at -20 degrees C and freeze-dried. The cross-linkage of Col molecules was introduced dehydrothermally at 140 degrees C in vacuo. The porous composite had a porosity of 94.7% with pore sizes between 200 and 500 microm. The compressive stress for the wet porous composite in phosphate buffer saline (PBS) was gradually decreased during 20 days incubation with a small amount of weight loss. The cyclic and time-course compression tests showed good repeatability of stress and well-recovery of its height, and caused no collapse of the porous composite. The implantation of the porous composite in rat bone holes showed the biodegradable property and new bone formation occurred in the pores without inflammatory response. The porous composite fabricated has good flexibility and rubber-like elasticity, and is a promising bone regenerative material.
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Affiliation(s)
- Shunji Yunoki
- Biomaterials Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
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37
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Yunoki S, Mori K, Suzuki T, Nagai N, Munekata M. Novel elastic material from collagen for tissue engineering. J Mater Sci Mater Med 2007; 18:1369-75. [PMID: 17277984 DOI: 10.1007/s10856-007-0121-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Accepted: 03/08/2006] [Indexed: 05/13/2023]
Abstract
Elastic collagen gel (e-gel) was prepared from salmon atelocollagen fibrillar gel reinforced by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) mediated cross-linking (f-gel). The preparation consisted of a simple heat treatment of the f-gel at 80 degrees C, in which the f-gel drastically shrank and the collagen fibril structure was deformed. The e-gel obtained showed rubber-like elasticity; its stress-strain behavior little changed through repeated stretching. The elongation at the breaking point was approximately 230%. Furthermore, normal human osteoblasts showed good attachment and proliferation on the e-gel. These results suggest its potential to be utilized for the development of tissue engineering.
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Affiliation(s)
- Shunji Yunoki
- Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
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Kino R, Ikoma T, Yunoki S, Nagai N, Tanaka J, Asakura T, Munekata M. Preparation and characterization of multilayered hydroxyapatite/silk fibroin film. J Biosci Bioeng 2007; 103:514-20. [PMID: 17630122 DOI: 10.1263/jbb.103.514] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Accepted: 02/28/2007] [Indexed: 11/17/2022]
Abstract
We prepared multilayered films consisting of silk fibroin (SF) and hydroxyapatite (HAp) by alternating lamination using untreated SF and HAp-deposited SF films. Untreated SF films were prepared from a regenerated SF solution by air drying. HAp-deposited SF films were prepared by soaking methanol-treated SF films containing >5 wt% CaCl2 in a simulated body fluid with the ion concentration 1.5-fold higher than that of the standard one. The multilayered HAp/SF films had HAp layers with approximate thicknesses of 3-5 microm and SF layers with thicknesses of 40-70 microm. The bonding strength between the SF and HAp layers was significantly affected by temperature and compression time under the lamination method. The optimal conditions for achieving the maximum T-peel strength and beta-sheet contents were determined to be 130 degrees C for 4 min. The Young's modulus of the multilayered films (133.4 MPa) was higher than that of the films consisting of SF alone (92.5 MPa) under swollen conditions. The biocompatibility of the HAp-deposited SF films was analyzed by culturing of osteoblasts (MC3T3-E1) on a film. The results indicate that HAp-deposited SF films and SF films show similar degrees of cell adhesion and alkaline phosphatase activities.
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Affiliation(s)
- Rikako Kino
- Faculty and Graduate School of Engineering, Hokkaido University, Kita 13, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
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Monkawa A, Ikoma T, Yunoki S, Ohta K, Tanaka J. Collagen coating on hydroxyapatite surfaces modified with organosilane by chemical vapor deposition method. J Nanosci Nanotechnol 2007; 7:833-8. [PMID: 17450842 DOI: 10.1166/jnn.2007.524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Type I collagen was coated onto the modified surfaces of hydroxyapatite (HAp) sintered body. The interfacial interaction between collagen and HAp in a nano-region was controlled by depositing the organosilane of n-octadecyltrimethoxysilane (ODS: -CH3) or aminopropyltriethoxysilane (APTS: -NH2) with a chemical vapor deposition method. The surfaces were elaborated by X-ray photoelectron spectroscopy, zeta-potential, and contact angle measurements; the Si and/or N peaks were detected, and the contact angles and surface energies were apparently different on the modified surfaces. The morphologies of collagen adsorbed on the surfaces of HAp and HAp deposited with APTS were similar, however that of the surface with ODS was apparently different, due to the hydrophobic interaction between the organic head group of -CH3 and residual groups of collagen.
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Affiliation(s)
- Akira Monkawa
- National Institute for Materials Science, Biomaterials Center, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
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Yunoki S, Ikoma T, Monkawa A, Ohta K, Tanaka J. Preparation and characterization of hydroxyapatite/collagen nanocomposite gel. J Nanosci Nanotechnol 2007; 7:818-21. [PMID: 17450839 DOI: 10.1166/jnn.2007.504] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The self-organized hydroxyapatite/colagen (HAp/Col) nanocomposite fiber (79.6/20.4 weight ratio) was synthesized by a co-precipitation method using Ca(OH)2, H3PO4, and Col as starting substances. The gelation of the nanocomposite is essential in the application of the scaffold for bone tissue engineering. We successfully prepared HAp/Col nanocomposite gels by a facile novel method using a sodium phosphate buffer at pH 6.8. The water-insoluble nanocomposite was homogeneously dispersed in the buffer to form a viscous mixture, and gels were obtained after incubating of the mixture at 37 degrees C. The mechanical strength of the gels was analyzed against the incubation time. The demineralized gel with EDTA had the typical nanostructure of native type I Col fibers from the results of scanning electron microscopy (SEM) and atomic force microscopy (AFM); the dense network of type I Col nano-fibers below 100 nm in diameter, and the periodic pattern of 68.8+/-4.4 nm (mean +/- SD) along the fibers were observed. The gelation of the HAp/Col nanocomposite in the buffer is attributed to the physical cross-linking through entanglement of the reconstituted Col fibrils.
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Affiliation(s)
- Shunji Yunoki
- National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
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Monkawa A, Ikoma T, Yunoki S, Yoshioka T, Tanaka J, Chakarov D, Kasemo B. Fabrication of hydroxyapatite ultra-thin layer on gold surface and its application for quartz crystal microbalance technique. Biomaterials 2006; 27:5748-54. [PMID: 16905184 DOI: 10.1016/j.biomaterials.2006.07.029] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Accepted: 07/26/2006] [Indexed: 10/24/2022]
Abstract
We present a method for coating gold quartz crystal microbalance with dissipation (QCM-D) sensor with ultra-thin layer of hydroxyapatite nanocrystals evenly covering and tightly bound to the surface. The hydroxyapatite layer shows a plate-like morphology and less than 20 nm in thickness. The hydroxyapatite sensor operated in liquid with high stability and sensitivity. The in-situ adsorption mechanism and conformational change of fibrinogen on gold, titanium and hydroxyapatite surfaces were investigated by QCM-D technique and Fourier-transform infrared spectroscopy. The change of secondary structures of fibrinogen adsorbed on the surfaces depended on the adsorbed amounts of protein. The secondary structure of fibrinogen adsorbed on the surfaces changes with increasing coverage. This is explained by repulsion among fibrinogens, affecting water structure and thus the strength of fibrinogen interactions on the surface. The study indicates that the hydroxyapatite sensor is applicable for qualitative and conformational analysis of protein adsorption.
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Affiliation(s)
- Akira Monkawa
- Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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Yunoki S, Ikoma T, Tsuchiya A, Monkawa A, Ohta K, Sotome S, Shinomiya K, Tanaka J. Fabrication and mechanical and tissue ingrowth properties of unidirectionally porous hydroxyapatite/collagen composite. J Biomed Mater Res B Appl Biomater 2006; 80:166-73. [PMID: 16767734 DOI: 10.1002/jbm.b.30581] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This study investigated the effects of the three-dimensional (3-D) pore structure of a porous hydroxyapatite/collagen (HAp/Col) composite on their mechanical properties and in vivo tissue ingrowth. The unique 3-D pore structure, comprising unidirectionally interconnected pores, was fabricated by the unidirectional growth of ice crystals by using a cooling stage and a subsequent freeze-drying process. The unidirectional pores had a spindle-shaped cross section, and their size gradually increased from the bottom to the upper face. The porous composite showed an elastic property and anisotropic compressive strength for the pore directions. While the strength and modulus parallel to the pore axis were 1.3- and twofold higher than those of the porous composite with spherical pores formed randomly, the strength and modulus perpendicular to the pore axis showed the lowest values. The subcutaneous implantations revealed that when compared with the random pores, the unidirectional pores promote the ingrowth of the surrounding tissues into the pores.
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Affiliation(s)
- Shunji Yunoki
- Biomaterials Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
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Nagai N, Yunoki S, Suzuki T, Sakata M, Tajima K, Munekata M. Application of cross-linked salmon atelocollagen to the scaffold of human periodontal ligament cells. J Biosci Bioeng 2005; 97:389-94. [PMID: 16233648 DOI: 10.1016/s1389-1723(04)70224-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Accepted: 03/19/2004] [Indexed: 11/27/2022]
Abstract
The purpose of this study was to investigate the application of salmon atelocollagen (SAC) to a scaffold. SAC has a low denaturation temperature and needs to be cross-linked before being used as a scaffold. In the present study, SAC was cross-linked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) or dehydrothermal treatment (DHT). The material properties (degree of cross-linking and solubility in phosphate-buffered saline) of the SAC scaffolds cross-linked by EDC (EDC-SAC) and DHT (DHT-SAC) were evaluated. It was found that EDC-SAC had a high degree of cross-linking and high stability compared with DHT-SAC. Human periodontal ligament (HPDL) cells were cultured in the scaffolds for 2 weeks in vitro, and the activities (proliferation rate and alkaline phosphatase [ALP] activity) of HPDL cells cultured in EDC-SAC and DHT-SAC were compared with those cultured in bovine atelocollagen (BAC) scaffolds cross-linked by EDC (EDC-BAC) and DHT (DHT-BAC), respectively. The proliferation rate of HPDL cells cultured in EDC-SAC was equivalent to that in EDC-BAC, and the ALP activity in EDC-SAC was found to be significantly higher than that in EDC-BAC. In the cross-linking by DHT, the cell proliferation rate and the ALP activity in DHT-SAC were lower than those in DHT-BAC. DHT seemed to provide insufficient cross-linking, and DHT-SAC was found to be breakable and contractile, resulting in less cell activity. In contrast, there was no difference in the thermal stability, porous structure, and cell proliferation rate between EDC-SAC and EDC-BAC. In addition, the collagen helix of EDC-SAC was found to be partially denatured, and this structure resulted in the enhancement of ALP activity of HPDL cells compared with that using EDC-BAC. In conclusion, our results indicate that EDC-SAC could be used as a scaffold for in vitro culture.
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Affiliation(s)
- Nobuhiro Nagai
- Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, N13-W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
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Yunoki S, Dagotto E, Sorella S. Role of strong correlation in the recent angle-resolved photoemission spectroscopy experiments on cuprate superconductors. Phys Rev Lett 2005; 94:037001. [PMID: 15698307 DOI: 10.1103/physrevlett.94.037001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Indexed: 05/24/2023]
Abstract
Motivated by recent photoemission experiments on cuprates, the low-lying excitations of a strongly correlated superconducting state are studied numerically. It is observed that along the nodal direction these low-lying one-particle excitations show a linear momentum dependence for a wide range of excitation energies and, thus, they do not present a kinklike structure. The nodal Fermi velocity v(F), as well as other observables, are systematically evaluated directly from the calculated dispersions, and they are found to compare well with experiments. It is argued that the parameter dependence of v(F) is quantitatively explained by a simple picture of a renormalized Fermi velocity.
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Affiliation(s)
- S Yunoki
- Istituto Nazionale per la Fisica della Materia and International School for Advanced Studies, via Beirut 4, 34014 Trieste, Italy
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Kino R, Ikoma T, Monkawa A, Yunoki S, Munekata M, Tanaka J, Asakura T. Deposition of bone-like apatite on modified silk fibroin films from simulated body fluid. J Appl Polym Sci 2005. [DOI: 10.1002/app.22910] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Yunoki S, Sorella S. Resonating valence bond wave function for the two-dimensional fractional spin liquid. Phys Rev Lett 2004; 92:157003. [PMID: 15169309 DOI: 10.1103/physrevlett.92.157003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2003] [Indexed: 05/24/2023]
Abstract
The unconventional low-lying spin excitations, recently observed in neutron scattering experiments on Cs2CuCl4, are explained with a spin liquid wave function. The dispersion relation as well as the wave vector of the incommensurate spin correlations are well reproduced within a projected BCS wave function with gapless and fractionalized spin-1/2 excitations around the nodes of the BCS gap function. The proposed wave function is shown to be very accurate for one-dimensional spin-1/2 systems and remains similarly accurate in the two-dimensional model corresponding to Cs2CuCl4, thus representing a good ansatz for describing spin fractionalization in two dimensions.
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Affiliation(s)
- S Yunoki
- Istituto Nazionale di Fisica della Materia (INFM)-Democritos, National Simulation Centre, and Scuola Internazionale Superiore di Studi Avanzati (SISSA), I-34014 Trieste, Italy
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Yunoki S, Nagai N, Suzuki T, Munekata M. Novel biomaterial from reinforced salmon collagen gel prepared by fibril formation and cross-linking. J Biosci Bioeng 2004; 98:40-7. [PMID: 16233664 DOI: 10.1016/s1389-1723(04)70240-6] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Accepted: 04/22/2004] [Indexed: 11/15/2022]
Abstract
The improvement of the thermal stability of gel prepared from salmon atelocollagen (SC) was studied. The denaturation temperature (Td) of the SC solution was found to be 18.6 degrees C. Neutral buffer including 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) was mixed with acidic SC solution at 4 degrees C, resulting in the introduction of EDC cross-linking during fibril formation. The mechanical strength and thermal stability of the resultant cross-linked SC fibrillar gels reached maximum values at an EDC concentration of 50 mM (f-50 gel). In particular, the melting temperature of the f-50 gel was 47 degrees C, much higher than that of the EDC cross-linked SC gel without fibril formation at the same EDC concentration. The proliferation rate of human periodontal ligament cells on the f-50 gel was higher than that of a porcine atelocollagen fibrillar gel. These results suggest that the gel employed for biomaterials can be fabricated from low Td fish collagen by EDC cross-linking during fibril formation.
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Affiliation(s)
- Shunji Yunoki
- Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
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Nagai N, Yunoki S, Satoh Y, Tajima K, Munekata M. A method of cell-sheet preparation using collagenase digestion of salmon atelocollagen fibrillar gel. J Biosci Bioeng 2004; 98:493-6. [PMID: 16233743 DOI: 10.1016/s1389-1723(05)00319-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2004] [Accepted: 09/16/2004] [Indexed: 10/25/2022]
Abstract
We prepared a cell sheet by using collagenase treatment to digest salmon atelocollagen fibrillar gel (SAC gel) on which human periodontal ligament (HPDL) cells had been cultured. The SAC gel was found to be digested completely within 2 h at a concentration of 50 U of collagenase per mg of collagen. The SAC gel on which HPDL cells were cultured for 10 d was treated with collagenase, resulting in the formation of a detached and shrunken cell sheet. Immunostaining results showed that the cytoskeleton and fibronectin matrix level of the cell sheet were maintained after collagenase treatment. In addition, collagenase treatment had almost no effect on the activities of HPDL cells.
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Affiliation(s)
- Nobuhiro Nagai
- Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, N13-W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
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Yunoki S, Suzuki T, Takai M. Stabilization of low denaturation temperature collagen from fish by physical cross-linking methods. J Biosci Bioeng 2003; 96:575-7. [PMID: 16233576 DOI: 10.1016/s1389-1723(04)70152-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Accepted: 09/09/2003] [Indexed: 10/26/2022]
Abstract
Collagen matrices were prepared from atelo salmon collagen (SC). SC has a lower denaturation temperature (19 degrees C) than mammalian collagen. SC matrices were successfully stabilized by ultraviolet irradiation and dehydrothermal treatment, and their optimum conditions were determined. By sponging at 37 degrees C, partial denaturation of the collagen molecules resulted in shrinkage of the matrices.
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Affiliation(s)
- Shunji Yunoki
- Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
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Elfimov IS, Yunoki S, Sawatzky GA. Possible path to a new class of ferromagnetic and half-metallic ferromagnetic materials. Phys Rev Lett 2002; 89:216403. [PMID: 12443438 DOI: 10.1103/physrevlett.89.216403] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2002] [Indexed: 05/24/2023]
Abstract
We introduce a path to a possibly new class of magnetic materials whose properties are determined entirely by the presence of a low concentration of specific point defects. Using model Hamiltonian and ab initio band structure methods we demonstrate that even large band gap nonmagnetic materials as simple as CaO with a small concentration of Ca vacancies can exhibit extraordinary properties. We show that such defects will initially bind the introduced charge carriers at neighboring sites and depending on the internal symmetry of the clusters so formed, will exhibit "local" magnetic moments which for concentrations as low as 3% transform this nonmagnetic insulator into a half-metallic ferromagnet.
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Affiliation(s)
- I S Elfimov
- Solid State Physics Laboratory, Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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