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Physicochemical properties of gelatin gels prepared using citric acid derivative

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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Optimization of DNA microsensor arrays for biological detection

Optimization of DNA microsensor arrays for biological detect...

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ASME 2000 International Mechanical engineering Congress and Exposition, IMECE 2000

作者： Gau, Jen-Jr Lan, Esther H. Dunn, Bruce Ho, Chih-Ming Biomedical Engineering Interdepartmental Graduate Degree Program University of California Los Angeles United States Department of Materials Science and Engineering University of California Los Angeles United States Department of Mechanical and Aerospace Engineering University of California Los Angeles United States

ISBN: (纸本)9780791819005

This paper describes the characterization and optimization of a reusable DNA microsensor array for rapid biological agent detection developed in previous publications. (Fig.l) [1-3] This MEMS based DNA sensor utilizes a standard three-electrode electrochemical cell configuration with novel micro fabricated structure design to minimize non-specific binding. The sensor module is easily to be adapted to various protocols and can be used for rapid detection of macromolecules (DNA, RNA) from targets such as uropathogenic Escherichia coli (E. coli) in urine and microorganisms causing otitis media (middle ear infection). Less than 105 E. coli cells can be detected from the urine sample of a patient with urine tract infection. The sensitivity is enhanced by appropriate sensor characterization and surface modification. The total detection time including sample preparation can be reduced to 25 minutes by using a POD conjugated oligonucleotide. Copyright © 2000 by ASME

关键词： DNA

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Preparation of blood-compatible nanoparticles bearing phosphorylcholine group

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ACS Symposium Series 2000年 752卷 417-427页

作者： Ishihara, Kazuhiko Konno, Tomohiro Kurita, Kimio Iwasaki, Yasuhiko Nakabayashi, Nobuo Department of Materials Science Graduate School of Engineering University of Tokyo Hongo Bunkyo-ku Tokyo 113-8656 Japan College of Science and Technology Nihon University Chiyoda-ku Tokyo 101-8356 Japan Inst. of Biomaterials and Bioeng. Tokyo Medical and Dental University Chiyoda-ku Tokyo 101-0062 Japan

The biodegradable poly (L-lactic acid) (PLA) nanoparticles covered with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer were prepared by the solvent evaporation technique with the amphiphilic water-soluble MPC polymer as the emulsifier. The diameter of the nanoparticles was approximately 200 nm, which was determined by atomic force microscopy and dynamic light scattering. X-ray photoelectron spectroscopy analysis indicated that the surface of the nanoparticles was fully covered with the MPC polymer. The amount of plasma protein bovine serum albumin adsorbed on the nanoparticles coated with the MPC polymer was significantly smaller compared with that on the polystyrene nanoparticles. The PLA nanoparticles coated with the MPC polymer is suggested to be a safer drug carrier in the bloodstream. One of the anticancer drugs, adriamycin (ADR), could be adsorbed on the nanoparticles through a hydrophobic interaction. Even when the nanoparticles were stored in PBS for 5 days, 40 % of the ADR still remained on the surface. We concluded that the nanoparticles coated with the MPC polymer are useful as a novel adsorption-type drug carrier, which could be applied through the bloodstream.

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Semi-interpenetrating polymer networks composed of biocompatible phospholipid polymer and segmented polyurethane

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Journal of Biomedical materials Research Part B: Applied biomaterials 2000年第4期52卷

作者： Yasuhiko Iwasaki Yoshiyuki Aiba Nobuyuki Morimoto 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

2-Methacryloyloxyethyl phosphorylcholine (MPC) polymers, which have excellent biocompatibility, have been receiving increasing attention in biomedical and bioengineering fields; however, the mechanical strength of the hydrated MPC polymers is not sufficient for use in these fields as a bulk material. Therefore, we hypothesized that a novel material might be realized by reinforcing the MPC polymer network with segmented polyurethane (SPU). Semi-interpenetrating polymer networks (IPNs) composed of crosslinked MPC polymer and SPU were prepared. The mechanical properties of the IPN membrane were significantly improved compared with those of the MPC polymer membrane. Three-dimensional polymer networks of the MPC polymer in the IPNs were observed after solvent extraction of SPU. An X-ray photoelectron spectrum analysis revealed that the MPC units were exposed on the IPN surface. When the IPN was alternately soaked in water and ethanol, the swelling ratio was found to be completely reversible and no disintegration of the network structure was observed. The permeation coefficient of 1,4-di(2-hydroxyethoxy)benzene through the IPN membrane was 1.11 × 10 −7 cm −2 s −1 . The amount of adsorbed protein and the number of adherent platelets on the IPN membrane were effectively reduced compared with those on SPU. We concluded that IPNs composed of the MPC polymer and SPU are a new bulk biomaterial, which possesses both blood compatibility and good mechanical properties. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 701–708, 2000.

关键词： hydrogel phospholipid polymer segmented polyurethane interpenetrating polymer networks protein adsorption biocompatibility

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In vivoevaluation of the bond strength of adhesive 4-META/MMA-TBB bone cement under weight-bearing conditions

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Journal of Biomedical materials Research Part B: Applied biomaterials 2000年第1期52卷

作者： Tomoko Sakai Sadao Morita Ken-ichi Shinomiya Akihiko Watanabe Nobuo Nakabayashi Kazuhiko Ishihara Department of Orthopedic Surgery Faculty of Medicine Tokyo Medical and Dental University 1-5-45 Yushima Bunkyo-ku Tokyo 113-8549 Japan Institute of Biomaterials and Bioengineering Tokyo Medical and Dental University Tokyo Japan Department of Materials Science Graduate School of Engineering The University of Tokyo Tokyo Japan

In order to minimize the problems associated with implant fixation using acrylic bone cement, we studied a new adhesive bone cement that consists of 4-methacryloyloxyethyl trimellitate anhydryde (4-META) and methylmethacrylate (MMA) as monomers, tri- n -butylborane (TBB) as an initiator, and PMMA powder (4-META/MMA-TBB cement). It shows remarkable adhesive properties to metal and bone in vitro . The purpose of this study was to evaluate the strength of the bond of the cement to both metal and bone in vivo under weight-bearing conditions. Metal prostheses were implanted in the right femora of 12 rabbits using either adhesive 4-META/MMA-TBB cement or the conventional PMMA cement, as the control, for fixation. After 4 and 12 weeks, both femora were excised and the same operations were performed in the left femora in vitro . Eighteen femora were sectioned for the mechanical assessment of the bone–cement and cement–implant interfaces. 4-META/MMA-TBB cement had a significantly higher interfacial shear strength than the conventional PMMA cement: 201 N and 90 N, on average, for the implant–cement interface ( p < 0.01); and 138 N and 89 N, on average, for the bone–cement interface ( p < 0.01), at 12 weeks. The present results suggest the efficacy of 4-META/MMA-TBB cement in providing greater fixation of implants to bone and promise a firmer intramedullary fixation than the control conventional PMMA cement. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 128–134, 2000.

关键词： bone cement 4-META bonding mechanical test

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