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Novel bone graft model using bead-cell sheets composed of tricalcium phosphate beads and bone marrow cells

materials science and engineering: C 2004年第6-8期24卷 875-879页

作者： Shunsuke Miyauchi Katsuko S. Furukawa Yoshikazu Umezu Yasuyuki Ozeki Takashi Ushida Tetsuya Tateishi Biomedical Engineering Laboratory Department of Mechanical Engineering Graduate School of Engineering University of Tokyo 503 8th Building 7-3-1 Hongo Bunkyo Tokyo 113-8656 Japan Advance Co. Saitama Japan Division of Biomedical Materials and Systems Center for Disease Biology and Integrative Medicine School of Medicine The University of Tokyo Japan Biomaterials Center National Institute for Materials Science Ibaraki Japan

Cells on scaffold implanted in vivo need nutrient and oxygen carried on the blood stream. In this respect, many scaffolds consisting of porous ceramics cannot hold cells alive in the center of them. Therefore, osteogenesis and substitution of regenerated bone occur from the surface of graft, and the biodegradation speed is slow. To solve this problem of lack of blood stream, we developed a new bone graft sheet composed of human bone marrow stromal cells (HMSCs), and beta-tricalcium phosphate (beta-TCP) porous beads. In addition, by combining multilayered bead-cell sheets and collagen gel, we fabricated a bone graft having the space for entry of blood vessels, and implanted them subcutaneously in mice. After 3 weeks, blood vessels reaching to the focal area of graft were recognized, and near the surface of graft, osteogenesis was also observed. In conclusion, the bead-cell sheet would have good osteoconductivity, and the graft made of bead-cell sheets showed a new design concept of bone graft preparing the space for neovascularization.

关键词： Bone tissue engineering Sheet Bead Bone marrow cell

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Transistor characteristics of thermal CVD carbon nanotubes field emission triode

Transistor characteristics of thermal CVD carbon nanotubes f...

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International Conference on Vacuum Nanoelectronics (IVNC)

作者： Y.M. Wong W.P. Kang J.L. Davidson W. Hofmeister S. Wei J.H. Huang Dept. of Electrical Engineering and Computer Science Vanderbilt Univ. Nashville TN USA Interdisciplinary Graduate Program in Material Science Vanderbilt Univ. Nashville TN USA Dept. of Materials Science and Engineering National Tsing Hua Univ. Hsinchu Taiwan ROC

In this paper, the study of thermal CVD grown CNT field emitters in a triode amplifier configuration is reported. The DC characteristics of the CNT triode are investigated, including I/sub a/ vs. V/sub a/ for different V/sub g/. Moreover, DC parameters such as transconductance, amplification factor and anode resistance of the triode amplifier are determined. It was shown that a higher amplification factor can be achieved with optimum gate-anode-cathode spacing such that the cathode is effectively shielded from the anode by the gate but the anode still collects all electrons emitted from the cathode. High emission current at low gate voltage is key to achieving high transconductance. This can be obtained by optimum configuration of high-density CNTs array in a triode structure with a common gate.

关键词： Carbon nanotubes Voltage Anodes materials science and technology Current measurement Palladium Silicon Furnaces Temperature Cathodes

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Bonding of soft tissues using a novel tissue adhesive consisting of a citric acid derivative and collagen

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materials science and engineering: C 2004年第6-8期24卷 775-780页

作者： Tetsushi Taguchi Hirofumi Saito Yoshiyuki Uchida Masataka Sakane Hisatoshi Kobayashi Kazunori Kataoka Junzo Tanaka Biomaterials Center National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Furuuchi Chemical Corporation 6-17-17 Minami-Oi Shinagawa-ku Tokyo 140-0013 Japan Institute of Clinical Medicine Tsukuba University 1-1-1 Tennodai Tsukuba Japan Department of Materials Sciences and Engineering Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan

A novel tissue adhesive consisting of collagen and citric acid derivative (CAD) was developed. In this adhesive, CAD works as a cross-linking reagent of collagen. CAD was prepared by modifying three carboxyl groups of citric acid with N -hydroxysuccinimide in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride. From 1 H-NMR spectrum, three active ester groups were introduced into one citric acid molecule with a high yield, exceeding 80%. The bonding strength of this tissue adhesive to porcine soft tissue increased with increasing CAD and collagen concentration. The maximum bonding strength of this adhesive was similar to the roughly 80% tear strength of the original soft tissue. The IC 50 of CAD for the L929 fibroblast was 10 times less cytotoxic than was that of the glutaraldehyde and formaldehyde used in aldehyde-based adhesive. This adhesive had biodegraded under the skin of mice within 7 days after subcutaneous injection. These results suggest that this newly developed adhesive is applicable as a bonding reagent for soft tissue.

关键词： Tissue adhesive Collagen Citric acid N -hydroxysuccinimide Gel Cross link

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Synthesis of activated poly(α,β-malic acid) using N -hydroxysuccinimide and its gelation with collagen as biomaterials

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materials science and engineering: C 2004年第6-8期24卷 815-819页

作者： Tetsuto Kajiyama Hisatoshi Kobayashi Tetsushi Taguchi Hirofumi Saito Yu Kamatsu Kazunori Kataoka Junzo Tanaka Department of Environmental Chemistry College of Environmental Engineering and Architecture Kanazawa Institute of Technology 7-1 Ohgigaoka Nonoichi Ishikawa 921-8501 Japan Biomaterials Center National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Furuuchi Chemical Corporation 6-17-17 Minamioi Shinagawa-ku Tokyo 140-0013 Japan Department of Materials Science and Engineering Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan

The development of synthetic biodegradable polymers, such as poly(α-hydroxy acid), is particularly important for constructing medical devices, including scaffolds and sutures, and has attracted growing interest in the biomedical field. Here, we report a synthesis method for activated polymalic acid (Su-PMA) by the reaction between synthesized α,β-PMA and N -hydroxysuccinimide (HOSu) in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC), and present an evaluation of the gelation properties of Su-PMA with collagen. The Su content of the resulting Su-PMA is higher than the feed ratio. Su content and chain length of Su-PMA influence gelation properties, as Su-PMA with low Su content formed a gel.

关键词： Poly(α,β-malic acid) Collagen Gel N -hydroxysuccinimide Water-soluble polymer Cross-linker

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Physicochemical properties of gelatin gels prepared using citric acid derivative

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materials science and engineering: C 2004年第6-8期24卷 781-785页

作者： Hirofumi Saito Tetsushi Taguchi Hisatoshi Kobayashi Kazunori Kataoka Junzo Tanaka Shun Murabayashi Yoshinori Mitamura Graduate School of Information Science and Technology The University of Hokkaido N-14 W-9 Kita-ku Sapporo 060-0814 Japan Furuuchi Chemical Corporation 6-17-17 Minamioi Shinagawa-ku Tokyo 140-0013 Japan Biomaterials Center National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan

We have developed a novel cross-linking reagent, citric acid derivative (CAD) in order to prepare gelatin gels. CAD was prepared by the modification of three carboxyl groups of citric acid with N -hydroxysuccinimide in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride. Gelatin gels were successfully obtained in the presence of CAD. Using the gelatin gels, residual amino group content, swelling ratio and enzymatic degradability were evaluated. Residual amino groups in gelatin gels decreased with increasing CAD concentration. On the other hand, swelling ratio of gelatin gels decreased with increasing CAD concentration up to 70 mM, then increased at elevated CAD concentration. Enzymatic degradation behavior was also correlated to the swelling ratio of gelatin gels. These results suggested that gelatin gels prepared at CAD concentration of 70 mM had minimum cross-linking density.

关键词： Cross-linking reagent Biopolymer Citric acid derivative Gel Gelatin

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Application of PLGA-collagen hybrid mesh for three-dimensional culture of canine anterior cruciate ligament cells

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materials science and engineering: C 2004年第6-8期24卷 861-866页

作者： Guoping Chen Takashi Sato Masataka Sakane Hajime Ohgushi Takashi Ushida Junzo Tanaka Tetsuya Tateishi Biomaterials Center National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Research Institute for Cell Engineering National Institute of Advanced Industrial Science and Technology 3-11-46 Nakoji Amagasaki Hyogo 661-0974 Japan Department of Orthopedics Institute of Clinical Medicine University of Tsukuba Tsukuba Japan Center for Disease Biology and Integrative Medicine Graduate School of Medicine The University of Tokyo 113-0033 Tokyo Japan

Canine anterior cruciate ligament (ACL) cells were isolated from the anterior cruciate ligament and subcultured in DMEM containing 10% FBS. After being subcultured twice, the ACL cells were seeded in a PLGA-collagen hybrid mesh and cultured in DMEM containing 10% FBS in vitro for 16 days. After 1 day, the cells adhered and spread well on collagen microsponges of the hybrid mesh. The cells proliferated and excreted extracellular matrices with culture time. After 16 days of culture, the cells and extracellular matrices occupied the spaces in the scaffold. At that point, the cell/mesh constructs were rolled up and implanted subcutaneously in the dorsum of nude mouse. The implants were harvested after 2, 4, 8, and 12 weeks of implantation and examined by histological staining. The implants were macroscopically white. Histological examination of cross sections of the implant by hematoxylin and eosin staining showed a large population of cells and newly deposited collagen in the rolled implants seeded with ACL cells. The cells were surrounded with bundles of collagen fibers. The layers in the rolled implant became integrated after 8 weeks. The polymer fibers could still be seen 8 weeks after implantation and gradually degraded and eventually disappeared after 12 weeks.

关键词： Tissue engineering ACL Ligament Hybrid scaffold Collagen PLGA

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Cover Picture: Two-Dimensional Multiarray Formation of Hepatocyte Spheroids on a Microfabricated PEG-Brush Surface (ChemBioChem 6/2004)

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ChemBioChem 2004年第6期5卷 729-729页

作者： Hidenori Otsuka Dr. Akihiro Hirano Yukio Nagasaki Dr. Teruo Okano Dr. Yasuhiro Horiike Dr. Kazunori Kataoka Dr. Department of Materials Science and Engineering Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Tokyo 113-8656 Japan Fax: (+81) 3-5841-7139 Present address: Biomaterials Center National Institute for Materials Science (NIMS) 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Department of Materials Science Tokyo University of Science Noda Chiba 278-8510 Japan Institute of Advanced Biomedical Engineering and Science Tokyo Women's Medical University 8-1 Kawadacho Shinjuku-ku Tokyo 162-8666 Japan

The cover picture shows a simple and effective way to construct a 2D microarray of 10 000 hepatocyte heterospheroids, underlaid with endothelial cells, through a combination of surface PEG treatment and subsequent microfabrication of plasma etching. The micropatterned PEG-treated region works to repel proteins and consequently inhibits cell adhesion, while the glass circular domains (Ø=100 μm), separated by PEG-treated regions ( l =100 μm), provide cell adhesive regions. This spheroid array is very useful as a platform for tissue and cell-based biosensors, which can be used as an alternative to animal experiments in a variety of situations. For more details, see the article by Kataoka et al. on p. 850 ff.

关键词： biosensors endothelial cells hepatocytes high-throughput screening microarrays

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Effects of Surface Roughness and Maximum Load on the Mechanical Properties of Cancellous Bone Measured by Nanoindentation

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MRS Online Proceedings Library 2004年第1期823卷 W8.5.1-W8.5.6页

作者： Donnelly, Eve Baker, Shefford P. Boskey, Adele L. van der Meulen, Marjolein C. H. Sibley School of Mechanical and Aerospace Engineering Cornell University Ithaca USA Department of Materials Science and Engineering Cornell University Ithaca USA Musculoskeletal Integrity Program Hospital for Special Surgery New York USA Department of Biochemistry Weill Medical College of Cornell University New York USA Graduate Program in Physiology Biophysics and Systems Biology Weill Medical College of Cornell University New York USA

Nanoindentation was used to assess the mechanical properties of lamellar and interlamellar tissue in dehydrated rabbit cancellous bone. The effects of surface roughness and maximum nanoindentation load on the measured mechanical properties were examined in two samples of differing surface roughness using maximum loads ranging from 250-3000 μN. As the ratio of indentation depth to surface roughness decreased below approximately 3:1, the variability in material properties increased substantially. At low loads, the indentation modulus of the lamellar bone was approximately 20% greater than that of the interlamellar bone, while at high loads the measured properties of both layers converged to an intermediate value. Relatively shallow indentations made on smooth surfaces revealed significant differences in the properties of lamellar and interlamellar bone that are consistent with microstructural observations of lamellar bone as more mineralized than interlamellar bone.

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Pressure, Temperature, and Thickness Dependence of CO2-Induced Devitrification of Polymer Films

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Physical Review Letters 2003年第17期91卷 175503-175503页

作者： Joseph Q. Pham Stephen M. Sirard Keith P. Johnston Peter F. Green Graduate Program in Materials Science and Engineering University of Texas at Austin Austin Texas 78712 USA Department of Chemical Engineering and Texas Materials Institute University of Texas at Austin Austin Texas 78712 USA

The glass transition temperature is known to increase with decreasing film thickness h for sufficiently thin poly(methyl methacrylate) films supported by silicon oxide substrates. We show that this system undergoes a CO2 pressure-induced devitrification transition, Pg, which is film thickness dependent, Pg(h)=ΔPg+Pgbulk. Pgbulk is the bulk glass transition and ΔPg can be positive or negative depending on T and P. The phenomenon of retrograde vitrification, wherein the polymer exhibits a rubbery-to-glassy-to-rubbery transition upon changing temperature isobarically, is also shown to occur in this system and it is film thickness dependent.

关键词： Polymethyl methacrylates

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Preservation of platelet function on 2-methacryloyloxyethyl phosphorylcholine–graft polymer as compared to various water-soluble graft polymers

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Journal of Biomedical materials Research Part B: Applied biomaterials 2001年第1期57卷

作者： Yasuhiko Iwasaki Nobuo Nakabayashi Kazuhiko Ishihara Institute of Biomaterials and Bioengineering Tokyo Medical and Dental University 2-3-10 Kanda-surugadai Chiyoda-ku Tokyo 101-0062 Japan Department of Materials Science Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan

The chemical structures of water-soluble polymers grafted onto PE surfaces affect platelet function when the platelets contact the polymer surfaces. To improve our understanding of this effect, this study sought to control the blood/materials interaction on the surfaces of polyethylene (PE) by grafting with various water-soluble polymers. Such polymers as poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), poly(acrylamide) (PAAm), poly( N -vinylpyrrolidone) (PVPy), and poly[monomethacryloyl poly(ethylene glycol)] (PMPEG) were grafted on low-density PE sheets by photoinduced graft polymerization. Both the PE bags modified with water-soluble polymers and those nonmodified were prepared by heat processing. Activation of platelets after storage in the PE bags was evaluated by measuring the cytoplasmic free calcium ion concentration ([Ca 2+ ] i ). The concentration of [Ca 2+ ] i of platelets in contact with the PE surface grafted with PMPC was the same as that of native platelets and significantly less than that in contact with other PE surfaces grafted with water-soluble polymers. The number of adherent platelets was effectively decreased on PE surfaces grafted with PMPC and PMPEG, as compared with nontreated PE. The aggregation ability of platelets was also measured after storage of platelet-rich plasma in the PE bags. The PE surface grafted with PMPC effectively maintained aggregation ability as compared with both the nontreated PE and with PE grafted with PAAm, PVPy, and PMPEG. It was concluded that for preserving platelet function, PMPC was the most effective of these water-soluble polymers used for surface modification. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 72–78, 2001

关键词： 2-methacryloyloxyethyl phosphorylcholine water-soluble polymer blood compatibility photoinduced polymerization platelet activation platelet aggregation

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