研究者データベース

柚木 俊二(ユノキ シユンジ)
産学・地域協働推進機構
特任教授

基本情報

所属

  • 産学・地域協働推進機構

職名

  • 特任教授

連絡先

  • yunokishunjiresearch.hokudai.ac.jp

科研費研究者番号

  • 20399398

J-Global ID

研究キーワード

  • コラーゲン   化粧品   生体高分子   医工学   バイオマテリアル   

研究分野

  • ライフサイエンス / 生体材料学

職歴

  • 2022年04月 - 現在 北海道大学 産学・地域協働推進機構 特任教授
  • 2008年06月 - 2021年03月 地方独立行政法人東京都立産業技術研究センター

学歴

  • 2001年04月 - 2004年03月   北海道大学   大学院工学研究科   分子化学専攻 博士後期課程
  • 1996年04月 - 1998年03月   北海道大学   大学院工学研究科   分子化学専攻 博士前期課程

研究活動情報

論文

  • Takashi Hoshiba, Shunji Yunoki
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS 2022年07月 
    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.
  • Yoshiyasu Nagakawa, Satoshi Fujita, Shunji Yunoki, Takayoshi Tsuchiya, Shin-ichiro Suye, Kenji Kinoshita, Motoki Sasaki, Takao Itoi
    JOURNAL OF MATERIALS CHEMISTRY B 10 23 4375 - 4385 2022年06月 
    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.
  • Shunji Yunoki, Hirosuke Hatayama, Yoshimi Ohyabu, Kazuto Kobayashi
    INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES 203 361 - 368 2022年04月 
    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 ?, one of the highest among fish collagens. BC formed CFM which was thermally stable at 37 ?, while Td was lower than 37 ?. This could be explained by the fast fibril formation, initiating at temperatures near 20 ?& nbsp;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.
  • Toshio Uraoka, Shunji Yunoki, Motoki Sasaki, Satoshi Kinoshita, Yusaku Takatori, Yuichiro Hirai, Takefumi Narita, Hemchand Ramberan, Masayuki Shimoda, Naohisa Yahagi
    DIGESTIVE ENDOSCOPY 34 1 105 - 112 2022年01月 
    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 mm) 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 days post-procedure.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 days, 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.
  • Takeya Kawamura, Shunji Yunoki, Yoshimi Ohyabu, Toshio Uraoka, Kazuaki Muramatsu
    MATERIALS 14 21 2021年11月 
    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 & DEG;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.
  • Toshio Uraoka, Shunji Yunoki, Satoshi Kinoshita, Yusaku Takatori, Yuichiro Hirai, Hirohito Tanaka, Takefumi Narita, Masayuki Shimoda
    DIGESTIVE ENDOSCOPY 33 4 616 - 620 2021年05月 
    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 CO(2)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.
  • Masushi Kohta, Yoshinori Nakamura, Shunji Yunoki
    CHRONIC WOUND CARE MANAGEMENT AND RESEARCH 8 1 - 11 2021年 
    Purpose: This study evaluated the effect of a new secondary dressing used as a topical aid sliding sheet for friction and shear force reduction on the mechanical stresses generated on human skin, including interface friction and internal shear force and pressure, using a polyurethane gel-based skin model. A case study was conducted to propose on how to clinically use the topical aid sliding sheet for pressure injury treatment in a home-care setting.Methods: A polyurethane gel-based skin model mimicking the mechanical properties of human skin was prepared. In parallel measurement of interface friction and internal shear force and pressure was performed using an experimental model consisting of the skin model, primary wound dressing, topical aid sliding sheet, and three-axis tactile sensor. The skin model was covered with the following single or combined dressings: group A, silicone-faced absorbent dressing (control); group B, silicone-faced absorbent dressing plus film dressing; and group C, silicone-faced absorbent dressing plus topical aid sliding sheet. Clinically, a standard primary wound dressing was applied to a female patient (age, 101 years) with pressure injury on the sacral region, and the dressing was overwrapped with the topical aid sliding sheet.Results: The static and dynamic coefficients of friction were significantly lower in group C than in groups A and B (p < 0.05). The detected shear force in the skin model was reduced to approximately 66% and 62% in group C versus groups A and B, respectively (p < 0.05). Clinically, the patient's ulcer underwent complete epithelialization without wound-related complications.Conclusion: The topical aid sliding sheet significantly reduced interface friction and internal shear forces in the present skin model. The case study's result showed the topical aid sliding sheet had the potential to use for pressure injury treatment at a home care.
  • Yurina Sekine, Takuya Nankawa, Shunji Yunoki, Tsuyoshi Sugita, Hiroshi Nakagawa, Teppei Yamada
    ACS APPLIED POLYMER MATERIALS 2 12 5482 - 5491 2020年12月 
    We developed a cross-linking method using freeze concentration and used it to synthesize a carboxymethyl cellulose nanofiber (CMCF) hydrogel with high water content (>94%), high compressive strength (>80 MPa), and high compressive recoverability. The hydrogels were prepared by adding an aqueous solution of citric acid (CA) to a frozen CMCF sol and then thawing the sol. The reaction between the freeze-concentrated CMCF and CA created a rigid porous structure with a pore diameter of approximately 80 mu m, which resembled the ice crystal structure. The stress-strain curves of the hydrogel during repeated compression up to 80% strain were similar over three cycles, which indicated that their cross-linked structure had high stability to compressive stress. Without the freeze cross-linking method, the complex of the CMCF sol and CA produced hydrogels, which easily collapsed under compressive stress. Bentonite was immobilized on a CMCF hydrogel by adding bentonite to the CMCF sol before freeze cross-linking. The CMCF-bentonite hydrogel showed high adsorptivity for chemical dyes, and the equilibrium sorption capacities for rhodamine B, basic blue 7, methylene blue, and malachite green were 353, 370, 207, and 234 mg g(-1), respectively. The physically cross-linked CMCF hydrogels are nontoxic, metal-free, and simple to prepare, and thus, they may be useful as sustainable materials in various fields.
  • Yoshiyasu Nagakawa, Satoshi Fujita, Shunji Yunoki, Takayoshi Tsuchiya, Shin-ichiro Suye, Takao Itoi
    JOURNAL OF APPLIED POLYMER SCIENCE 137 28 2020年07月 
    We have developed a novel self-expandable biliary stent comprising poly(vinyl alcohol) (PVA). The swelling ratio of the dried PVA hydrogels decreased from 6.7 to 2.6 as the saponification degree increased from 95 to 99.9, whereas the storage modulus and tear strength increased from 17 to 400 kPa and from 0.5 to 10 N mm(-1), respectively. The dimensional ratios of the inner- and outer-diameter and the length of the dried tube-shaped hydrogels (saponification degree of 98.5) prepared by simple air drying isotropically increased 1.4-1.5 times in physiological saline. Meanwhile, the dimensional ratios of the dried hydrogels prepared by drying under extension increased by twice, whereas the length decreased slightly, indicating anisotropic swelling. The radial force of the reswollen tube-shaped hydrogels (6.6 +/- 0.6 mN mm(-2)) was significantly higher than that of a conventional metallic stent (4.4 +/- 0.3 mN mm(-2)), suggesting that PVA hydrogels were applicable as self-expandable stents. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48851.
  • Hidenaga Kobashi, Shunji Yunoki, Motozumi Itoi, Takeshi Ide, Jun Shimazaki, Kazuo Tsubota
    INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE 61 7 2020年06月 
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  • Dawei Meng, Hiroyuki Tanaka, Taishi Kobayashi, Hirosuke Hatayama, Xi Zhang, Kazuhiro Ura, Shunji Yunoki, Yasuaki Takagi
    INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES 131 572 - 580 2019年06月 
    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. (C) 2019 Elsevier B.V. All rights reserved.
  • Shunji Yunoki, Hirosuke Hatayama, Mizue Ebisawa, Eiji Kondo, Kazunori Yasuda
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS 107 4 1011 - 1023 2019年05月 
    We developed a continuous formation method of cord-like collagen gels comprising fibrils preferentially aligned along the geometrical axes (CCGs). Collagen (2.5%) dissolved in a sodium phosphate buffer containing 280 mM of sodium chloride was introduced into a stainless cylinder (length 52 mm, diameter 2.0 mm) warmed at 38 degrees C at a linear velocity of 2.5 mm/s. This process caused collagen fibril alignments under acute fibril formation in the cylinder, resulting in continuous formation of CCGs. Fibril formation rate, shear rate, and shear duration were substantial factors for successful CCG formation. Outstanding advantages of this method over conventional wet spinning include the capacity of this technique to form aligned fibrils in the entire gels and to control the diameter of cord-like gels over 1 mm. The air-drying of CCGs which were crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxy-succinimide produced dry collagen fibers with cross-sectional areas of 0.0123-0.135 mm(2). Upon the rewetting of the fibers, they failed at a stress of 54.5 +/- 7.8 MPa, which is higher than the mean failure stress of anterior cruciate ligament tissue (13.3-37.8 MPa). These findings indicate that the CCG formation method enables the fabrication of collagen fibers which are potential components of collagen-based artificial tendons. (c) 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1011-1023, 2019.
  • Yusaku Takatori, Toshio Uraoka, Takefumi Narita, Shunji Yunoki, Naohisa Yahagi
    ENDOSCOPY INTERNATIONAL OPEN 7 4 E561 - E567 2019年04月 
    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 5.5mMol with 24 hours worming time and NaCl 280mMol. PSC/Ge had better mechanical property than PSC. It was efficiently integrated and confined to the SM with acceptable toxicity. MH of PSC/Ge (5.10.74mm) and PSC (4.8 +/- 0.84mm) were significantly higher than NS (3.2 +/- 0.84mm). 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.
  • Shunji Yunoki, Kiyoji Sugimoto, Yoshimi Ohyabu, Hiroyuki Ida, Yosuke Hiraoka
    FOOD SCIENCE AND TECHNOLOGY RESEARCH 25 2 217 - 226 2019年03月 
    Manual pipette methods are conventionally used to determine the viscosity (eta) of gelatin solutions. The purpose of this study is to demonstrate the accuracy and precision of viscosity measurements of gelatin solutions using a rotational rheometer. Seven gelatin samples with different molecular weights were tested. The 2 x standard deviations of the obtained eta were within +/- 2.4 % of the mean values in triplicate measurements, suggesting the evident precision of the viscosity measurements. Accuracy was demonstrated by the triplicate measurements of the standard liquids for a viscometer. The sample volume required by the rheometer was only 0.6 mL, whereas gelatin solutions of approximately 100 mL are usually required for pipette methods. We propose viscosity measurement using a rheometer as an alternative method to the pipette ones.
  • Ryosuke Tonozuka, Shunji Yunoki, Takao Itoi, Atsushi Sofuni, Takayoshi Tsuchiya, Kentaro Ishii, Reina Tanaka, Mitsuyoshi Honjo, Shuntaro Mukai, Mitsuru Fujita, Kenjiro Yamamoto, Yasutsugu Asai, Yukitoshi Matsunami, Takashi Kurosawa, Hiroyuki Kojima, Yuichi Nagakawa, Yoshiyasu Nagakawa
    JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY 34 1 194 - 201 2019年01月 
    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.
  • Yusaku Takatori, Toshio Uraoka, Takefumi Narita, Shunji Yunoki, Yasuo Hosoda, Naohisa Yahagi
    GASTROINTESTINAL ENDOSCOPY 87 6 AB272 - AB272 2018年06月
  • Toshio Uraoka, Shunji Yunoki, Takefumi Narita, Yuichiro Hirai, Masayuki Shimoda, Naohisa Yahagi
    GASTROINTESTINAL ENDOSCOPY 87 6 AB248 - AB248 2018年06月
  • Toshio Uraoka, Satoshi Kinoshita, Shunji Yunoki, Takefumi Narita, Yusaku Takatori, Hideki Mori, Kaoru Takabayashi, Motohiko Kato, Yuichiro Hirai, Masayuki Shimoda, Naohisa Yahagi
    GASTROINTESTINAL ENDOSCOPY 85 5 AB505 - AB505 2017年05月
  • Takefumi Narita, Shunji Yunoki, Yoshimi Ohyabu, Naohisa Yahagi, Toshio Uraoka
    MEDICAL DEVICES-EVIDENCE AND RESEARCH 9 429 - 439 2016年 
    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 degrees 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.
  • Shunji Yunoki, Hirosuke Hatayama, Mizue Ebisawa, Eiji Kondo, Kazunori Yasuda
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 103 9 3054 - 3065 2015年09月 
    In this study, we developed a fabrication method for thick collagen gel bundles comprising uniaxially aligned fibrils of sufficient size for filling defects in ligament tissues. The fabrication involved rotary shearing to dense collagen sols using a rheometer and then warming them from 23 degrees C to 37 degrees C to trigger gelation upon rotation. Gelation due to collagen fibril formation was accelerated by increased concentrations of neutral phosphate buffer, and fibril alignment occurred within 20 s during the early stage of rapid gelation. Fabrication of gels was completed with slippage between gels and the movable upper plate, and well-aligned fibrils along the rotation direction were observed in the marginal regions of disc-shaped gels. Gel thickness could be increased from 1 to 3 mm with homogeneous alignment of fibrils in the entire sample. The alignment of fibrils improved mechanical properties against tensile loads that were placed parallel to the alignment axis. Elongation of cultured fibroblast along the alignment was observed on the gels. The present method will enable the bottom-up fabrication of an artificial tendon for ligament reconstruction and repair. (C) 2015 Wiley Periodicals, Inc.
  • Shunji Yunoki, Masushi Kohta, Yoshimi Ohyabu, Tetsuji Iwasaki
    CHRONIC WOUND CARE MANAGEMENT AND RESEARCH 2 1 - 9 2015年 
    Purpose: This study evaluated the in vitro antibacterial activity and cytotoxicity of various commercially available silver-containing dressings (Ag dressing).Methods: Biohesive Ag (hydrocolloid, silver sulfadiazine), Aquacel (R) Ag (nonwoven fabric, ionic silver [Ag+]), Algisite (TM) Ag (nonwoven fabric, Ag+), Mepilex (R) Ag (foam, silver sulfate), and PolyMem (R) Ag (foam, nanocrystalline silver) were tested for characteristics of Ag+ release, antibacterial activity, and cytotoxicity. The release of Ag+ was investigated in cell culture medium at immersion periods of 6, 24, and 48 hours. The antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa were accessed by a disc diffusion test. The cytotoxicity was evaluated using V79 cells, by an extraction method.Results: The cytotoxicity was not a monotonic function of the antibacterial activity among the Ag dressings and could not be simply explained by Ag+-release properties. Biohesive Ag was regarded as a slow-release Ag dressing, showing the lowest cytotoxicity, while the antibacterial activity was classified as "strong" or "significant" against the two species of bacteria. Aquacel Ag and Algisite Ag showed higher antibacterial activity and cytotoxic effects, which were supported by the higher Ag+ release. Mepilex Ag showed the highest release of Ag+, and the cytotoxicity was the highest among the Ag dressings. However, the antibacterial activity was classified as "significant" or "no activity" for P. aeruginosa and S. aureus, respectively. PolyMem Ag showed the lowest Ag+ release, and the antibacterial activity classified as "significant" or "no activity" for S. aureus and P. aeruginosa, respectively, whereas the cytotoxicity was similar to those of Aquacel Ag and Algisite Ag.Conclusion: The efficacy and adverse effects of the Ag dressings revealed differences that should be considered by clinicians during wound management.
  • Yoshimi Ohyabu, Hirosuke Hatayama, Shunji Yunoki
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 118 1 112 - 115 2014年07月 
    We prepared uncleaved gelatin composed mainly of collagen alpha-, beta-, and gamma-chains. Gelation and melting of uncleaved gelatin occurred rapidly with moderate decrease and increase in temperature (23 degrees C-37 degrees C). The viability of cells encapsulated in the gelatin gel was greater than 96% after 7 d at 23 degrees C. (C) 2013, The Society for Biotechnology, Japan. All rights reserved.
  • Shunji Yunoki, Masushi Kohta, Yoshimi Ohyabu, Masayuki Sekiguchi, Takabumi Kubo, Tetsuji Iwasaki
    JOURNAL OF APPLIED POLYMER SCIENCE 131 13 2014年07月 
    Polymeric systems for antibacterial wound dressings require chemical reactions or syntheses for attaching or incorporating antibacterial moieties into polymer backbones. However, these materials often fail to satisfy the basic requirements, such as easy and inexpensive synthesis. We speculated that a positively charged organic antibacterial agent would be attracted to the polar groups of poly(vinyl alcohol) (PVA) hydrogels and would show suppressed release. PVA hydrogels containing cetylpyridinium chloride (CPC) were prepared by irradiation. CPC was barely released from the hydrogels, probably because of electrostatic interactions, and was stable upon irradiation. The suppressed release of CPC conferred antibacterial activity against Escherichia coli to the surface of the hydrogels, whereas no inhibition zone was observed around the hydrogels. The CPC-containing PVA hydrogels were easy to prepare and contained known and safe materials. The simplicity and safety of this procedure for achieving the suppressed release of antibacterial agents were advantages of these CPC-containing PVA hydrogels. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40456.
  • Yoshiyasu Nagakawa, Shunji Yunoki, Masaaki Saito
    POLYMER TESTING 33 13 - 15 2014年02月 
    Bio-based polyethylene (bio-PE) is chemically identical to conventional fossil-based PE. The only method to differentiate them is radiocarbon (C-14) analysis. The purpose of this study was to evaluate the potential of liquid scintillation counting (LSC) as a screening method. The pellets of bio-PE and fossil-PE were soaked in a scintillation cocktail, and measured by LSC. The counting rate of bio-PE increased as a function of time and then saturated (35 +/- 1.7 cpm) in 30 h. This counting rate was much higher than that of fossil-PE (3.3 +/- 0.5 cpm). Pre-soaking of PE in toluene (the solvent of the scintillation cocktail) enhanced the counting rate of bio-PE. Bio-PE with higher crystallinity showed a lower counting rate. These results suggest that the solvent of the scintillation cocktail permeated into the non-crystalline regions, inducing scintillation of bio-PE in the solid state. LSC is a potential high-throughput screening method to detect bio-PE. (C) 2013 Elsevier Ltd. All rights reserved.
  • Yoshimi Ohyabu, Shunji Yunoki, Hirosuke Hatayama, Yoshikazu Teranishi
    INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES 62 296 - 303 2013年11月 
    Collagen-based 3-D hydrogels often lack sufficient mechanical strength for tissue engineering. We developed a method for fabrication of high-density collagen fibril matrix (CFM) gels from concentrated solutions of uncleaved gelatin (UCG). Denatured random-coil UCG exhibited more rapid and efficient renaturation into collagen triple-helix than cleaved gelatin (CG) over a broad range of setting temperatures. The UCG solution formed opaque gels with high-density reconstituted collagen fibrils at 28-32 degrees C and transparent gels similar to CG at <25 degrees C. The unique gelation properties of UCG enabled the encapsulation of cultured cells in CFM of high solid volume (>5%) and elasticity (1.28 +/- 0.15 kPa at 5% and 4.82 +/- 0.38 kPa at 8%) with minimal cell loss. The elastic modulus of these gels was higher than that of conventional CFM containing 0.5% collagen. High-strength CFM may provide more durable hydrogels for tissue engineering and regenerative medicine. (C) 2013 Elsevier B.V. All rights reserved.
  • Tomoko Ikeda-Fukazawa, Naohiro Ikeda, Mayu Tabata, Masataka Hattori, Mamoru Aizawa, Shunji Yunoki, Yurina Sekine
    JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 51 13 1017 - 1027 2013年07月 
    To investigate the effects of crosslinker density on the properties of hydrogels, compression tests, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Raman measurements were performed on poly-N,N-dimethylacrylamide hydrogels. The results of the compression tests showed that the Young's modulus increases as the crosslinker density increases. To understand the mechanism of the change in the mechanical properties, the structures of the polymer networks and water and the molecular vibrations were analyzed using SEM, DSC, and Raman methods. From the SEM images, it was found that the porosity estimated from the mesh size and cell density increases with increasing crosslinker density. In addition, the DSC and Raman results show that the thickness of the bound water increases as the porosity increases, although the density of the polymer chains in the porous wall remains nearly constant. The increase in the number density of polymer chains can be one of the mechanisms contributing to the increase in the mechanical strength of the hydrogels at lower crosslinker density below 5 mol %, as proposed by previous studies. At higher crosslinker density, however, the number density of polymer chains does not increase with increasing crosslinker density. The present results suggest that the bound water plays an important role in strengthening the hydrogel. The water structure may be one of the dominant factors governing the chemical and physical properties of hydrogels. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 10171027
  • Shunji Yunoki, Yoshimi Ohyabu, Hirosuke Hatayama
    INTERNATIONAL JOURNAL OF BIOMATERIALS 2013 2013年 
    We investigated the temperature-responsive gelation of collagen/genipin solutions using pepsin-solubilized collagen (PSC) and acid-solubilized collagen (ASC) as substrates. Gelation occurred in the PSC/genipin solutions at genipin concentrations 0-2mM under moderate change in temperature from 25 to 37 degrees C. The PSC/genipin solutions exhibited fluidity at room temperature for at least 30 min, whereas the ASC/genipin solutions rapidly reached gel points. In specific cases PSC would be preferred over ASC as an injectable gel system. The temperature-responsive gelation of PSC/genipin solutions was due to temperature responses to genipin crosslinking and collagen fibril formation. The elastic modulus of the 0.5% PSC/genipin gel system could be adjusted in a range of 2.5 to 50 kPa by the PSC and genipin concentrations, suggesting that a PSC/genipin solution is a potential injectable gel system for drug and cell carriers, with mechanical properties matching those of living tissues.
  • Shunji Yunoki, Masayuki Sekiguchi, Seiko Nakagawa
    RADIATION MEASUREMENTS 47 7 561 - 564 2012年07月 
    In this study, PSL of non-irradiated and irradiated corrugated fiberboards (CFs) was investigated to evaluate the possibility that CFs can be used as alternative specimens for the screening detection method of food irradiation. The irradiation at a dose of only 0.15 kGy increased PSL signals of the CF over 1 order of magnitude. The PSL signals increased with increasing in gamma irradiation dose and became almost saturated at a dose of 5 kGy. The core of CFs showed PSL signals sufficient for distinguishing irradiated from non-irradiated at least 6 months after irradiation even though the CF was exposed to light and the environmental temperature increased to 50 degrees C. These results suggest that the PSL property of the core of CFs is useful for detecting irradiation. However, the large variation of PSL signals among CFs made it difficult to set a well-defined "positive" threshold limit to distinguish irradiated from non-irradiated completely. All of the non-irradiated CFs showed PSL signals above 10(3) counts, which is much higher than that detected for foods. It is apparent that the threshold limit of EN 13751 is not applicable to detecting irradiated CFs. More detailed collaborative research with large number of samples is needed to establish new threshold limits involving "intermediate" classification. (C) 2012 Elsevier Ltd. All rights reserved.
  • Shunji Yunoki, Hiroaki Sugiura, Toshiyuki Ikoma, Eiji Kondo, Kazunori Yasuda, Junzo Tanaka
    BIOMEDICAL MATERIALS 6 1 2011年02月 
    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.
  • Shunji Yunoki, Toshiyuki Ikoma, Junzo Tanaka
    MATERIALS CHARACTERIZATION 61 9 907 - 911 2010年09月 
    A major drawback of collagen sponges regarding their use in tissue engineering scaffolds is their weak mechanical properties under wet conditions. To overcome this problem without the use of other skeletal materials, the exhaustive condensation technique of reconstituted collagen fibrils was developed to fabricate high-density collagen sponges using freeze drying. The density linearly increased with an increase in the concentration of collagen fibrils. The compression tests under wet conditions demonstrated that the toughness and stiffness of the collagen sponges increased with an increase in the density. The collagen sponge with a density of 129 mg/cm(3) showed a compressive strength (to a strain of 30%) of 8.88 kPa and a modulus of 332 kPa. These results suggested the possibility that the mechanical properties of collagen sponges can increase significantly while retaining the sponges' inherent bioresorbability. (C) 2010 Elsevier Inc. All rights reserved.
  • Shunji Yunoki, Masaaki Saito
    BIORESOURCE TECHNOLOGY 100 23 6125 - 6128 2009年12月 
    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 C-14 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 C-14 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. in (C) 2009 Published by Elsevier Ltd.
  • Hiroaki Sugiura, Shunji Yunoki, Eiji Kondo, Toshiyuki Ikoma, Junzo Tanaka, Kazunori Yasuda
    JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 20 10 1353 - 1368 2009年 
    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. (C) Koninklijke Brill NV, Leiden, 2009
  • Shunji Yunoki, Takehisa Matsuda
    BIOMACROMOLECULES 9 3 879 - 885 2008年03月 
    In vitro "simultaneous processing" was investigated in which fibril formation of collagen and cross-linking occur simultaneously in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) as a cross-linking reagent. Fibril formation in simultaneous processing was monitored using turbidity. The EDC in simultaneous processing increased T-1/2 (time required for half of the plateau value in turbidity) and decreased the degree of the fibril formation dose dependently. The reduced fibril formation rate (T-1/2 > 60 s) suggests the introduction of intrafibrillar cross-linking during fibril formation. The collagen gels prepared using simultaneous processing had a compressive modulus that was 6-fold higher than that using sequential processing, which is an advantage of simultaneous processing. Atomic force microscopy images acquired under water on the wet gels demonstrated that the simultaneous processing provided a unique double-network structure: intrafibrillarly cross-linked collagen fibrils among which nonfibrous collagens act as interfibrillar cross-linkages.
  • Shunji Yunoki, Eriko Marukawa, Toshiyuki Ikoma, Shinichi Sotome, Hongsong Fan, Xingdong Zhang, Kenichi Shinomiya, Junzo Tanaka
    JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE 18 11 2179 - 2183 2007年11月 
    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.
  • Nobuhiro Nagai, Kazuo Mori, Yasuharu Satoh, Noritaka Takahashi, Shunji Yunoki, Kenji Tajima, Masanobu Munekata
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 82A 2 395 - 402 2007年08月 
    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. (c) 2007 Wiley Periodicals, Inc.
  • Shunji Yunoki, Kazuo Mori, Takeshi Suzuki, Nobuhiro Nagai, Masanobu Munekata
    JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE 18 7 1369 - 1375 2007年07月 
    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.
  • Rikako Kino, Toshiyuki Ikorna, Shunji Yunoki, Nobuhiro Nagai, Junzo Tanaka, Tetsuo Asakura, Masanobu Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 103 6 514 - 520 2007年06月 
    We prepared multilayered films consisting of silk fibroin (SF) and hydroxyapatite (HAp) by alternating lamination using untreated SF and HAp-deposited SIT films. Untreated SF films were prepared from a regenerated SIT 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 mu m and SIT layers with thicknesses of 4070 pm. 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 SIT films was analyzed by culturing of osteoblasts (MC3T3-E1) on a film. The results indicate that HAp-deposited SIT films and SIT films show similar degrees of cell adhesion and alkaline phosphatase activities.
  • Shunji Yunoki, Toshiyuki Ikoma, Akira Monkawa, Kazushi Ohta, Junzo Tanaka
    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 7 3 818 - 821 2007年03月 
    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.
  • Nobuhiro Nagai, Shunji Yunoki, Takeshi Suzuki, Yasuharu Satoh, Kenji Tajima, Masanobu Munekata
    CELL TECHNOLOGY FOR CELL PRODUCTS 321 - + 2007年 
    Salmon atelocollagen (SAC) has not been used as biomaterials due to its low denaturation temperature (19 degrees C). In the present study, we succeeded in preparation of SAC fibrillar gel stable at an actual physical temperature of human by cross-linking during fibril formation, and in cultivating human periodontal ligament cells on the cross-linked SAC fibrillar gel.
  • Shunji Yunoki, Toshiyuki Ikoma, Akio Tsuchiya, Akira Monkawa, Kazushi Ohta, Shinichi Sotome, Kenichi Shinomiya, Junzo Tanaka
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS 80B 1 166 - 173 2007年01月 
    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. (c) 2006 Wiley Periodicals, Inc.
  • Shunji Yunoki, Toshiyuki Ikoma, Akira Monkawa, Eriko Marukawa, Shinichi Sotome, Kenichi Shinomiya, Junzo Tanaka
    JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 18 4 393 - 409 2007年 
    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 pm. 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.
  • Shunji Yunoki, Toshiyuki Ikoma, Akira Monkawa, Kazushi Ohta, Junzo Tanaka, Shinichi Sotome, Kenichi Shinomiya
    JOURNAL OF THE AMERICAN CERAMIC SOCIETY 89 9 2977 - 2979 2006年09月 
    Gamma irradiation treatment (GIT) is the most widely used sterilization method for biomaterials in spite of the potential to degrade polymers. The adverse effects of GIT on the mechanical properties and biological stabilities of porous hydroxyapatite/collagen (HAp/Col) composites were investigated in this study. Those properties of a porous HAp/Col composite stabilized by dehydrothermal treatment (DHT) drastically decreased by GIT in the same manner as conventional pure Col materials. DHT after GIT could partially eliminate the adverse effects, due to the introduction of cross-linkage among the degraded Col molecules.
  • S. Yunoki, T. Ikoma, A. Monkawa, K. Ohta, M. Kikuchi, S. Sotome, K. Shinomiya, J. Tanaka
    Materials Letters 60 8 999 - 1002 2006年04月 
    The porous hydroxyapatite/collagen (HAp/Col = 80/20 in weight ratio) composite with unique three-dimensional pore structures was fabricated by the control of ice crystal growth using the liquid N2 as a cooling medium and subsequent freeze-dry process, and the pore structure and mechanical properties were evaluated by SEM and compression tests. The porous composite had the unidirectionally interconnected micropores along the ice growth direction with a spindle-shaped cross-section (distributed from 40.1 × 11.0 to 110 × 21.8 μm in size). When the container was set on a cooling stage at - 30 °C, the length of the long-axes (distributed from 75. 2 to 134.3 μm) reached the range that is necessary to bone tissue penetration. The defined pore structure improved its mechanical resistance against the compression and gave anisotropic compression properties against the pore directions. The porous HAp/Col composite with flexibility and shape recover properties will be a promised biomaterial for bone regeneration and other scaffold for tissue engineering. © 2005 Elsevier B.V. All rights reserved.
  • Rikako Kino, Toshiyuki Ikoma, Akira Monkawa, Shunji Yunoki, Masanobu Munekata, Junzo Tanaka, Tetsuo Asakura
    Journal of Applied Polymer Science 99 5 2822 - 2830 2006年02月05日 
    Silk fibroin films with various calcium chloride contents were prepared by a cast film method and subsequent MeOH treatment. The conformational changes from α-helix to β-sheet structure were analyzed by Fourier transformed infrared attenuated total reflection spectroscopy measurements. The films obtained were soaked in 1.5-times simulated body fluid (1.5 SBF) and the deposition of hydroxyapatite crystals were observed by scanning electron microscopy. The films with calcium chloride contents lower than 3 wt % relative to the silk fibroin were not mineralized under these conditions, while those with cal cium chloride contents more than 5 wt % mineralized after 6 h. The X-ray diffraction patterns and inductive coupled plasma spectroscopy analyses indicated that the hydroxyapatite crystals were grown by hydrolysis of octacalcium phosphate, as indicated by differences in diffraction intensities and changes in concentrations of calcium and phosphate ions in 1.5 SBF. © 2005 Wiley Periodicals, Inc.
  • Shunji Yunoki, Toshiyuki Ikoma, Akira Monkawa, Kazushi Ohta, Masanori Kikuchi, Junzo Tanaka
    Key Engineering Materials 309-311 II 1091 - 1094 2006年 
    Hydroxyapatite/collagen (HAp/Col) composite scaffold with unidirectionally elongated pores (scaffold-U) was fabricated by the unidirectional solidification with ice growth and subsequent freeze-dry process. The pore architecture in the composite was evaluated by using scanning electron microscopy (SEM) and micro computed tomography (micro-CT) with a high resolution. The SEM observation showed that the scaffold-U had unidirectional pores elongated along the vertical direction (i.e. ice growth direction), however the horizontal cross-section showed quite different pore morphology: spindle-shaped pores with random direction. The 3-D micro-CT image of the scaffold-U simultaneously showed the microstructure of the unidirectionally elongated pore and the cross-sectional pore, indicating that the interconnected micropores were successfully fabricated along the ice growth direction. The micro-CT is a powerful tool for the visualization of 3-D pore structure.
  • Kazushi Ohta, Toshiyuki Ikoma, Shunji Yunoki, Akira Monkawa, Junzo Tanaka
    Transactions of the Materials Research Society of Japan, Vol 31, No 2 31 2 345 - 348 2006年 
    Mesostructured calcium phosphates were synthesized by a sol-gel method using a micelle template; calcium nitrate tetrahydrate and diphosphorus pentaoxide were mixed in ethanol including the nonionic surfactant of Pluronic P123, which was then dried and heated in air. The inorganic/organic composite with the ordered 2D hexagonal structure was formed after drying. The heat treatment at 300 degrees C caused the formation of mesopores with the mean size of 3.9 nm; however, the ordered mesostructure disappeared due to the combustion and collapse of P123 in heating. The crystalline hydroxyapatite was obtained by heating at 500 degrees C.
  • Rikako Kino, Toshiyuki Ikoma, Shunji Yunoki, Akira Monkawa, Atsushi Matsuda, Go Kagata, Tetsuo Asakura, Masanobu Munekata, Junzo Tanaka
    Polymer Preprints, Japan 54 2 5042  2005年 
    Silk fibroin films containing 5wt% of CaCl2 (SFF-5) were prepared by a cast-film method from the degummed SF and then immersed into the simulated body fluid (SBF) to deposit hydroxyapatite (HAp) crystals. The multilayer films of HAp and SFF (Slayers) or pure SFF (4 layers) were prepared by a thermo-compression method under 130°C for 4min and at 3MPa. The ratio of □-sheet structure in both samples showed almost same value of 56 and 55%. The swelling ratio and in vitro biodegradation were examined by incubating in phosphate-buffered saline (PBS) with and without Protease XIV for 1 to 14 days. The changes of sample weight and its tensile strength were investigated. The biodegradation rate, calculated from its weight changes, indicated that the rate of pure multilayered SFF was higher than that of multilayered SFF containing HAp. It could be attributed to the adsorption of protease onto the HAp crystals and/or the inhibition of penetration of protease.
  • Nobuhiro Nagai, Shunji Yunoki, Yasuharu Satoh, Kenji Tajima, Masanobu Munekata
    Journal of Bioscience and Bioengineering 98 6 493 - 496 2004年12月 
    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.
  • Shunji Yunoki, Yoshiko Osada, Hiroyuki Kono, Mitsuo Takai
    Food Science and Technology Research 10 3 307 - 313 2004年08月 
    We studied the role of ethanol in the improvement of bacterial cellulose (BC) production, primarily using 13C NMR. 13C-labeled BC was biosynthesized by Acetobacter xylinum ATCC 10245 using culture media containing D-(1-13C), (2-13C), and (6- 13C)glucose. The introduction of (1-13C) ethanol was also investigated. Ethanol was not utilized as a carbon source for BC production, but was oxidized to acetic acid. The consumption rate of glucose and the extracellular conversion of glucose into gluconic acids were suppressed by the ethanol supplementation. The direct polymerization of the glucose into BC was accelerated; in contrast, the participation of the Entener-Doudoroff pathway was reduced by the ethanol supplementation. These results support the hypothesis that the improvement of BC production by ethanol supplementation can be achieved by the effective use of glucose. Ethanol could be used as a substitute for glucose and gluconic acids, and a source for metabolites in the tricarboxylic acid cycle.
  • Shunji Yunoki, Takeshi Suzuki, Mitsuo Takai
    Journal of Bioscience and Bioengineering 96 6 575 - 577 2003年 
    Collagen matrices were prepared from atelo salmon collagen (SC). SC has a lower denaturation temperature (19°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°C, partial denaturation of the collagen molecules resulted in shrinkage of the matrices.
  • Hiroyuki Kono, Shunji Yunoki, Tamio Shikano, Masashi Fujiwara, Tomoki Erata, Mitsuo Takai
    Journal of the American Chemical Society 124 25 7506 - 7511 2002年06月26日 
    The precise assignments of cross polarization/magic angle spinning (CP/MAS) 13C NMR spectra of cellulose Iα and Iβ were performed by using 13C labeled cellulose biosynthesized by Acetobacter xylinum (A. xylinum) ATCC10245 strain from culture medium containing D-[1,3-13C]glycerol or D-[2-13C]glucose as a carbon source. On the CP/MAS 13C NMR spectrum of cellulose from D-[1,3-13C]glycerol, the introduced 13C labeling were observed at C1, C3, C4, and C6 of the biosynthesized cellulose. In the case of cellulose biosynthesized from D-[2-13C]glucose, the transitions of 13C labeling to C1, C3, and C5 from C2 were observed. With the quantitative analysis of the 13C transition ratio and comparing the CP/MAS 13C NMR spectrum of the Cladophora cellulose with those of the 13C labeled celluloses, the assignments of the cluster of resonances which belong to C2, C3, and C5 of cellulose, which have not been assigned before, were performed. As a result, all carbons of cellulose Iα and Iβ except for C1 and C6 of cellulose Iα and C2 of cellulose Iβ were shown in equal intensity of doublet in the CP/MAS spectrum of the native cellulose, which suggests that two inequivalent glucopyranose residues were contained in the unit cells of both cellulose Iα and Iβ allomorphs.

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    研究期間 : 2020年08月 -2023年01月
  • 魚類コラーゲンに特徴的なミクロンレベルの大直径線維の成長機構と細胞分化誘導活性
    日本学術振興会:科学研究費助成事業 挑戦的研究(萌芽)
    研究期間 : 2019年06月 -2022年03月 
    代表者 : 都木 靖彰, 柚木 俊二, 成田 武文, 畑山 博哉, 浦 和寛
     
    研究実施計画 1.Ⅰ型線維形成,Ⅰ+Ⅱハイブリッド型線維形成過程の詳細観察 分担者が所属する東京都産業技術研究センターに導入された温度制御装置付の新型顕微鏡を用いることで,当初予定していた予定していたAFMよりも簡便かつ詳細に線維形成過程を観察することが可能になった. 研究実施計画 2.SBC線維の細胞機能活性化能の実証 SBC線維上で培養したMC3T3-E1骨芽細胞の分化初期(培養1日目)と後期(培養21日目)の遺伝子発現を,マイクロアレイを用いて網羅的に解析し,当初予測とは逆にコラーゲン線維に接着した細胞では多くの遺伝子の発現が抑制されることを示した.しかし,フィブロネクチンやVIII型コラーゲン遺伝子など,いくつかの細胞外基質遺伝子の発現は増加していた.このことから,コラーゲン線維に接着したMC3T3-E1骨芽細胞では,ある特定の遺伝子の発現が活性化される可能性が示唆される.一方で,コラーゲン線維に接着することが in vivo の状態に近いと考えると,コラーゲン分子に接着したMC3T3-E1骨芽細胞は,生体の骨折部位に観察されるような,外部刺激により骨芽細胞が活性化された状態にあるものと想像される.また,足場の物理的・化学的シグナルを感知することで細胞形態や増殖,分化を変化させる焦点接着(ビンキュリン)とそれに結合するF-アクチンを蛍光免疫染色し共焦点レーザー顕微鏡(CF-LSM)で観察したところ,コラーゲン線維に接着したMC3T3-E1骨芽細胞では分子に接着した細胞とはまったく異なる分布を示し,線維と分子ではまったく細胞接着機構が異なることが予想された.このことが分子と線維に接着した細胞の遺伝子発現を変化させる機構として細胞接着の様式の違いが予想される.
  • 瘢痕拘縮を予防し優れた創傷治癒を誘導する力学的支持性を有した人工真皮の開発
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2019年04月 -2022年03月 
    代表者 : 落合 博子, 柚木 俊二, 成田 武文, 岡 愛子, 平田 恵理, 大藪 淑美
     
    コラーゲンスポンジを基材とした人工真皮マトリクスは国際的に普及し、皮膚欠損創に対する植皮術を実施する前の肉芽形成においてその有用性が実証されている。国内の製品に着目すると、その開発研究が 1996 年に報告され既に製品化から20 年が経過しているが、大きな改善は行われていない。しかし、コラーゲンスポンジの強度が吸水により著しく低下することは本質的な課題として残されており、術後の瘢痕拘縮の要因の1つと考えられている。本研究は、コラーゲンスポンジが示す良好な肉芽形成能(すなわち生体吸収性と組織置換性)を維持しながら耐収縮性を付与する新たな試みと位置付けられる。 人工真皮として用いられているコラーゲンスポンジの内部に吸収性の骨格構造を付与した場合、力学的に支持された足場の効果により瘢痕拘縮が予防されるという仮説を立てた。本研究では、力学試験および小動物を用いたin vivo 実験によりこの仮説を検証することを目的とした。コラーゲン線維を高濃度化し、凍結乾燥により密度の異なる3種類のコラーゲンマトリクス(CM)を作製した。加えて、疎なコラーゲンマトリクス部に緻密なフレーム構造体を複合化したコラーゲンマトリクス(FCM)を3種類作製した。耐荷重性および肉芽形成を阻害しない構造となるように配慮し、実際に耐荷重性が高まっていることを確認した。マウス背部の皮下への埋入、皮膚欠損層への移植、皮膚欠損層へのFCM+植皮を実施し、実験系が異なることによるFCMの吸収の過程や炎症細胞出現数、肉芽形成、瘢痕拘縮について検討した。皮膚欠損層への移植に関してはFCMの耐荷重性の高さと吸収の遅さに比例関係を認めず、また瘢痕拘縮の有意差も認めなかった。今後はFCMの構造を変更し、追加実験を行っていく。また、形成された肉芽と生着した植皮の質の評価のために、免疫染色を実施しており、今後の実験計画の参考としたい。
  • 一軸配向化高靱性合成コラーゲンゲル線維束の生体内再構築に関する適応制御機序の解明
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2019年04月 -2022年03月 
    代表者 : 近藤 英司, 安田 和則, 柚木 俊二, 王 磊
     
    本研究の目的は、生体内の異なる生物学的および物理的環境(関節内・外、生理的負荷・除負荷)における、線維径の異なる一軸配向化合成コラーゲン線維束(合成腱マトリクス)の再構築現象を、凍結解凍処理腱(天然腱マトリクス)のそれと比較することにより、その適応制御機序を解明することである。令和2年度は、平成31年度に作製した線維径200μmおよび800μmの高靱性一軸配向化合成コラーゲン線維束を3次元化して直径2 mm、幅3 mm、長さ50 mmの合成コラーゲン束を作製した。SEMによる横断面の観察では、fascicle間にmicrosizeの間隙が観察された。細胞侵入性などの評価のため対照として凍結乾燥工程を用いない完全緻密性コラーゲンを作製した。SEMによる矢状面での観察では、気孔構造が見られない緻密構造が観察されたが、横断面の観察では一部空隙を持つ層構造が観察された。そのため対照のコラーゲン作製方法を調整(GAを加えて固定化、EtOHで脱水、t-BuOH凍結乾燥法で乾燥)し、SEMにて緻密体であることを確認した。 次に日本白色家兎を用いた膝蓋腱中央欠損モデルを用いて合成腱マトリクスの埋植実験を行った。全身麻酔後、膝に縦切開を加え右膝蓋腱の中央1/3を採取し、高靱性一軸配向化合成コラーゲン線維束を移植した。左膝には完全緻密性コラーゲンを移植して比較対照とした。術後3週における組織学的観察では、HE染色にてfascicle間に紡錘形の核を有する線維芽細胞様細胞が多数観察され、線維方向に配向性が観察された。一方、完全緻密性コラーゲンにおいてはコラーゲン内に細胞は観察されなかった。
  • タンパク質成型体が示す高温域での未知な軟化現象と熱融着機序の解明
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2019年04月 -2021年03月 
    代表者 : 成田 武文, 柚木 俊二, 大藪 淑美, 村松 和明
     
    本研究は模擬血管を医工学的手法により創製し、高温での軟化および接着を生じる層構造および生体高分子組成、模擬血管どうしの接着機序を接着界面部の組織学的評価により明らにすることである。 当該年度はゼラチンを用いて高温処理における物理的・形態的変化を明かにした。サンプルはゼラチン水溶液を冷却してゲル化させ凍結乾燥した物理架橋ゼラチン、およびゲル化時にゲニピンの橋架を導入した後に凍結乾燥した化学架橋ゼラチンを用いた。レオメーターでは200℃を超える温度で貯蔵弾性率が急激に低下し、サンプルの軟化現象を確認した。DSC では 80~100℃の範囲に相転移を認められた。サンプルを熱プレス機で加熱すると、130℃以上で軟化が観察され、2枚のシート状ゼラチンを接着させることができたが、200℃以上では著しい流動化が生じた。これらの結果から、レオメーターで計測された軟化は融点、DSCで計測された相転移はガラス転移点に対応すると考えられた。また、2枚のシート状サンプルを熱プレスし、剥離試験を行ったところ、加熱温度80℃~130℃の範囲で温度依存性の剥離強度が増加した。また、剥離面を観察するとミクロレベルの荒れが見られ、接着界面においては加熱温度の増加により不明瞭になっていたことから接着現象は融着によるものと推定された。 高温領域において、可塑剤を含まなくてもゼラチンの乾燥成形体が軟化し、熱融着を生じることを実証し、この熱融着には加圧が重要な因子であることが示唆された。
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2018年04月 -2021年03月 
    代表者 : 都木 靖彰, 吉田 誠一郎, 松嶋 景一郎, 柚木 俊二, 畑山 博哉, 佐伯 宏樹, 三輪 佳子
     
    水産廃棄物から得られるコラーゲンペプチド(CP)を「床ずれ」治療もしくは予防用クリームに利用することを目的に,まずCP生産の原料となる精製コラーゲンおよび高純度ゼラチンの製造技術開発をおこなった。その後,酵素を用いて製造したCPを高温高圧処理することでさらに低分子化できることを示すとともに,低分子化により抗酸化能が増すことを示した。しかし,高温高圧処理によっては皮膚線維芽細胞に対する機能性は高まらず,むしろ長時間の処理によっては細胞遊走が阻害されたりCPの細胞増殖活性化能がなくなった。これらの結果から,適度な高温高圧処理により抗酸化能が高く細胞活性化能を持つCPを合成できることを示した。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2018年04月 -2021年03月 
    代表者 : 土屋 貴愛, 柚木 俊二, 永川 栄泰, 糸井 隆夫
     
    ポリビニルアルコール(PVA)ゲルの吸水膨潤性を利用して,胆管ドレナージ用の全く新しい自己拡張型ハイドロゲルステント(HGS)を創出することに成功した.乾燥状態のHGSは既存の胆管プラスチックステントに類似し,吸水により膨張し狭窄を広げる事のできる拡張力を有していた. HGSを生体ブタ5匹に対し内視鏡的胆管ステント留置を行い,全例で成功し4週間飼育し,2例で自然脱落を認め,4週後胆管内に残存したステントはin vitro実験と同様,十分に拡張していた.抜去後の胆泥付着評価でマクロ的には目視できず,ミクロ的ごく微量の細菌類の付着が見られたのみで,既存のステントよりも閉塞しにくい可能性が示唆された.
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2018年04月 -2021年03月 
    代表者 : 柚木 俊二, 海老澤 瑞枝, 畑山 博哉, 近藤 英司
     
    先行研究で開発した配向コラーゲン線維ゲル連続成型技術を用いて、細胞侵入経路を持つコラーゲン/コンドロイチン硫酸(Chs)複合人工腱を開発した。幅3 mm、厚さ2 mmの棒状の人工腱を、家兎の膝蓋腱中央に作製したスリットへ埋植した。6週後には人工腱の大半が吸収され、腱のコラーゲン組織に置換されていた。6週から12週にかけてヤング率が減少する傾向を認め、組織再構築が生じたことが示唆された。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2016年04月 -2019年03月 
    代表者 : 浦岡 俊夫, 柚木 俊二, 成田 武文, 矢作 直久
     
    内視鏡的切除時の粘膜下層への“開発中の体温でゲル化する生体注入用コラーゲンソルを用いた注入術”の出血予防・潰瘍治癒効果を実証し、今後の実用化に繋げることを目的に研究を行った。 机上実験を繰り返し、注入用コラーゲンソルの条件が決定した。生体ブタの胃を用いた急性実験にて粘膜下局注剤としての粘膜下膨隆維持性と出血抑制効果を段階的に実証し、病理組織学的評価も行い、また、慢性実験にて局注後の状態の推移を内視鏡的・病理組織学的に評価した。 結果として、至適に条件設定されたコラーゲンソルを用いた内視鏡治療は安全性と有効性が示された。結果の一部は、国際学会と論文発表を行っている。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 柚木 俊二, 安田 和則, 近藤 英司, 大藪 淑美
     
    フィブリルが軸方向に配向した紐状コラーゲンゲル(CCG)の連続成型技術を開発した。リン酸緩衝液に溶解したコラーゲンを38℃に加温したステンレス管に導入する工程により、管内で急速なコラーゲンの線維化を生じ、CCGが連続的に吐出された。従来の湿式紡糸法に対する本法の優位性は、ゲル全層に渡りフィブリルを配向させることができ、更にゲルの直径を制御可能なことである。 CCGを乾燥させると断面積が0.0123~0.135 mm2のfiberを作製できた。湿潤状態での破断強度は54.5 ± 7.8 MPaに達し、ヒト靱帯に比肩した。このfiberの組紐によって細胞浸潤性を有する人工腱マトリックスを作製した。
  • 内視鏡治療で生じた消化管壁の穿孔を体温硬化性ゲルで簡易かつ確実に被覆する治療技術の開発
    国立研究開発法人 科学技術振興機構:A-STEP シーズ顕在化タイプ
    研究期間 : 2014年12月 -2015年11月 
    代表者 : 柚木俊二, 浦岡俊夫ら
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2012年04月 -2015年03月 
    代表者 : 柚木 俊二, 安田 和則, 近藤 英司, 畑山 博哉
     
    厚さ3 mmのゲルの全層にわたってコラーゲン線維が一軸配向する、天然の腱の基本構造を模した線維束の作製技術を開発した。高濃度コラーゲン水溶液の線維化速度を加速し、ゲル形成期に限定して剪断応力を付与すると、ゲルの破壊を伴うことなく配向コラーゲン線維束が得られた。線維配向性は線維芽細胞に認識されるに十分であり、線維束は天然腱類似の力学的異方性を示した。ウサギ膝蓋腱に埋植したゲル状の配向コラーゲン線維束は、細胞浸潤性を示さず、6週の間に力学特性の変化を生じなかった。本研究により、配向コラーゲン線維束の作製技術が一般化され、細胞浸潤を促す階層構造が人工腱にとって必要であることが明らかになった。
  • 生体組織類似の弾性率まで硬化する体温応答性インジェクタブルコラーゲンゲルの開発
    国立研究開発法人 科学技術振興機構:A-STEP探索タイプ
    研究期間 : 2012年11月 -2013年10月 
    代表者 : 柚木俊二
  • バイオ燃料混合ガソリン中のバイオ炭素比率の簡便な決定法
    国立研究開発法人 科学技術振興機構:A-STEP探索タイプ
    研究期間 : 2011年08月 -2012年03月 
    代表者 : 柚木俊二
  • 骨類似の力学的性質を有する次世代型骨機能修復材料の創生
    科学技術振興機構:産学共同シーズイノベーション化事業
    研究期間 : 2006年10月 -2007年09月 
    代表者 : 柚木俊二ら
  • ゼラチンゲルを保護材として用いた安全かつ簡易な細胞輸送システム
    国立研究開発法人 科学技術振興機構:A-STEP シーズ育成タイプ


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