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  • 1
    Electronic Resource
    Electronic Resource
    Fluorescent chemosensor for metal ions using a polymer having pendant pyridylbenzoxazole groups (2000)
    Springer
    Polymer bulletin 44 (2000), S. 79-84 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A polymer having fluorescent pyridylbenzoxazole groups has been prepared for the purpose of detecting of metal ions. Metal ions such as Co2+, Ni2+, Cu2+ and Fe2+ were found to coordinate with the bipyridyl-like fluorescent benzoxazole chromophores. Among the metal ions investigated, the Fe2+ ion was shown to be the most effective in terms of its fluorescence quenching ability. The addition of a metal scavenger 2,2'-dipyridyl to the metal ion-quenched polymer solution resulted in the recovery of the fluorescence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890050576
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  • 2
    Electronic Resource
    Electronic Resource
    In Vitro Chondrocyte Culture Using Hydrophilized PLLA Scaffold in Bioreactor System (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 342-343 (July 2007), p. 253-256 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Nonporous PLLA film and porous PLLA scaffolds were prepared and then grafted withacrylic acid (AA) using in situ direct plasma treatment to obtain PLLA-g-PAA. Chondrocytesisolated from rabbit knee articular cartilages were cultivated in Dulbecco’s modified eagle medium-F12 (DMEM-F12) containing 10% fetal bovine serum (FBS) and 1% antibiotics and passaged twicebefore cell seeding. Once seeded on either PLLA films or scaffolds, they were placed in abioreactor system and an intermittent hydrodynamic pressure (IHP) was applied in 3 bars, whileturned on for 2 min and off for 28 min during 15-day culture. AA grafting to PLLA surface wasconfirmed from various surface analyses. From WST-1 assay, chondrocyte proliferation wassignificantly improved with dynamic IHP for PLLA and PLLA-g-PAA scaffolds as compared tostatic culture. This study indicates that IHP may have significant influence on chondrocytesbehavior in 3D culture environment
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.342-343.253.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Blood Compatibility of Novel Zwitterionic PEG-Grafted Nitinol Alloy for Peripheral Arterial Stents (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 342-343 (July 2007), p. 805-808 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this study, newly synthesized zwitterionic PEG was grafted on Nitinol alloy usingoxidation treatment. The surface property and blood compatibility of surface-modified Nitinolswere examined. The results of surface analysis showed that the contact angle and the ratio ofoxygen to carbon significantly decreased with Nitinol alloys. The total amount of fibrinogen (0.095μg/cm2) adsorbed onto TiNi-PEG2K-N+-S- was lower than that of TiNi control (0.12 μg/cm2). Theplatelet adhesion decreased in the order of TiNi control 〉 TiNi-MPEG2K 〉 TiNi-PEG2K-N+-S.Particularly, zwitterionic PEG with PEG2K was proven better than any others. The results indicatedthat zwitterionic PEG surface could significantly suppress platelet adhesion and protein adsorptionas compared to other samples. The present study suggested that grafted zwitterionic PEG structuremay possess improved blood compatibility
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.342-343.805.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Evaluation of RGD-Grafted Porous PLLA Scaffold for Chondrogenic Differentiation of Stem Cells (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 342-343 (July 2007), p. 297-300 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Biodegradable porous poly(L-lactic acid) (PLLA) scaffolds were prepared using gasfoaming method. The PLLA scaffolds with a hydrophobic surface were subjected to Ar plasmatreatment and in situ acrylic acid (AA) grafting to obtain hydrophilic PLLA scaffold (PLLA-PAA).Cell-adhesive RGD peptide was then immobilized onto the AA-grafted PLLA (PLLA-PAA-RGD).Once rabbit bone marrow-derived mesenchymal stem cells (BM-MSC) were isolated, MSCs wereseeded into PLLA control, PLLA-PAA, and PLLA-PAA-RGD scaffold and cultured for up to 4weeks in chondrogenic medium with the addition of 10 ng/ml transforming growth factor (TGF)-β1.Surface analysis of AA-grafted PLLA identified significant alterations of surface characteristics,including reduced contact angle and different atomic compositions. From WST-1 assay at 4 weeks,cells were found more proliferative in PLLA-PAA than the others. Upon the histological analysis ofSafranin O staining, chondrogenic differentiation of MSCs appeared to be progressed more activelyin PLLA-PAA. The effect of RGD immobilization on MSC differentiation was barely notable
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.342-343.297.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Thermosensitive and Cell-Adhesive Pluronic Hydrogels for Human Adipose-Derived Stem Cells (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 342-343 (July 2007), p. 301-304 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Pluronic F127 has received increasing attention over many years as drug deliverysystems, biomaterials, and hydrogels for tissue engineering. In this study, we synthesizedtemperature-sensitive and cell-adhesive triblock F127 copolymers, in which Arg-Gly-Asp (RGD)peptide ligand was grafted to Pluronic F127-4-methacryloxyethyl trimellitic anhydride (4-META)to obtain F127-META-RGD. The chemical structures of the F127-META-RGD block copolymerswere confirmed by FTIR, 1H and 13C NMR, and GPC. The resultant F127-META-RGD showedvery similar thermosensitive behaviors to F127 and F127-META. The critical micelle temperature(CMT) of the F127 copolymers decreased in the order of F127 〈 F127-META 〈F127-META-RGD, whereas the particle size followed an opposite trend. Interactions between theF127 copolymers and adipose-derived stem cells (ASC) were evaluated in terms of cell adhesionand proliferation on the hydrogel. These thermosensitive RGD-grafted Pluronic hydrogels thatdisplay the enhanced cell adhesiveness, are expected to be useful as a functional injectable scaffoldfor tissue engineering
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.342-343.301.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Chondrogenic Differentiation of Human Adipose-Derived Stem Cells in PLGA (Poly(Lactic-Co-Glycolic Acid) Scaffold (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 342-343 (July 2007), p. 345-348 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Human adipose tissue contain a population of pluripotent stem cells capable ofdifferentiating along multiple mesenchymal cell lineages. The goal of this study was to examine thechondrogenic potential of adipose-derived stem (ADS) cells. ADS cells were isolated from humansubcutaneous adipose tissue obtained by lipectomy and liposuction, and were expanded and grownin vitro with or without chondrogenic medium in micromass culture condition and 3D culturecondition in PLGA(poly(lactic-co-glycolic acid)) scaffold. Human ADS cells of micromassculture condition and 3D culture condition in PLGA scaffolds, were differentiated withchondrogenic medium consisted of transforming growth factor-β1, insulin-transferrin-selenium,dexamethasone and ascorbate-2-phosphate. ADS cells abundantly synthesized cartilage matrixmolecules including collagen type II, VI and link protein. ADS cells under high-density micromassculture condition with chondrogenic medium formed well defined nodules within 48 hours ofinduction. On the 3rd week after chondrogenic differentiation of ADS cells under the micromassculture condition and 3D culture condition of PLGA scaffold, mRNA of type II collagen, type VIcollagen and link protein were expressed by reverse transcription polymerase chain reaction(RT-PCR). On the 3weeks, content of glycosaminoglycan in cells treated with chondrogenicmedium was greater than that with non chondrogenic medium(control).On the 3rd week cultureunder the chondrogenic medium, hematoxylin & eosin (H & E) staining, alcian blue stainingand type II collagen immunohistochemistry analysis confirmed the chondrogenic differentiation inmicromass and 3D cultured specimen. These findings document the ability of ADS cells to producecharacteristic cartilage matrix molecules, and provide the possibility of cartilage regeneration forcartilage substitution
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.342-343.345.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Surface structure and inert surface characteristics of perfluorodecanoic acid-grafted polyurethane (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 761-769 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The surface compositions and characteristics of perfluorodecanoic acid (PFDA)-grafted polyurethane (PU) were investigated to understand its enhanced blood compatibility. The grafting of PFDA was identified by attenuated total reflectance-Fourier transform infrared (ATR-FTIR). The results from angular-dependent electron spectroscopy for chemical analysis (ADESCA) demonstrated the fluorocarbon enrichment at the outermost layer in PFDA-grafted PU. Static secondary ion mass spectroscopy (SIMS) experiments supported the results drawn from ATR-FTIR and ADESCA data about the surface compositions. Energy-dispersive X-ray analysis (EDXA) data by fluorine mapping also indicated a considerable coverage with fluoroalkyl groups on the PU-PFDA surface. The critical surface tension, γc, of the highly hydrophobic PU-PFDA surface revealed an extremely low value of 6.9 dyn/cm due to the optimal orientation of —CF3 groups to the uppermost surface. Therefore, such an inert low-energy surface may contribute to improve blood compatibility of PFDA-grafted PU. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470502
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  • 8
    Electronic Resource
    Electronic Resource
    Antithrombogenicity of lumbrokinase-immobilized polyurethane (1994)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 1069-1077 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Lumbrokinase is a potent fibrinolytic enzyme purified from the earthworm, Lumbricus rubellus. We immobilized 18 IU/cm2 of lumbrokinase to polyurethane using maleic anhydride methylvinyl ether copolymer (MAMEC) as an enzyme carrier, and the proteolytic and fibrinolytic activities of immobilized lumbrokinase were assayed. Immobilized lumbrokinase retained about 34% of its activity, compared with soluble lumbrokinase activity. Immobilized lumbrokinase showed stability against thermal inactivation and degradation and within a various pH range. The optimal pH of immobilized lumbrokinase shifted 1.0 pH unit upward compared with soluble enzyme. Upon exposure to the human whole blood, less amount of 125I-fibrinogen was adsorbed to lumbrokinase-immobilized surface than to the polyurethane control surface. The lumbrokinase-immobilized surface showed less platelet adhesion than did the MAMEC-grafted surface. At the early stage of platelet adhesion, the number of adhered platelets increased on the lumbrokinase-immobilized surface with increasing time; yet, the platelet number drastically decreased on the lumbrokinase-immobilized surface after 80 min incubation. This suggests that lumbrokinase-immobilized polyurethane digested the adsorbed fibrinogen and inhibited platelet adhesion on the surface, probably by inhibiting fibrinogen adsorption to be highly antithrombogenic. Clinical applications of this material to artificial organs should be developed in the near future. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820280912
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation and surface characterization of PEO-grafted and heparin-immobilized polyurethanes (1989)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 87-104 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Surfaces of commercial polyurethanes (PUs) were modified by poly(ethylene oxide) (PEO) grafting and/or heparin immobilization for long-term biomedical applications. PU surfaces were treated with diisocyanate and then reacted with PEO or heparin. The heparin immobilized by various methods on the PU surface was very stable, with concentrations of 1.45-1.84 m̈g/cm2. Surface structure and characteristics of each modified PU were examined by performing the following surface analyses: attenuated total reflection infrared (ATR-IR), electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), and dynamic contact angle measurements. The reaction scheme and surface chemical structure of modified PUs were confirmed by ATR-IR and ESCA, respectively. SEM results showed that the PU-PEO surface was very smooth and that the smoothness of the heparinized PU surfaces varied, depending upon the solvent and coupling agent used in the process. The hydrophilicity of the surface was significantly increased after PEO grafting or heparin immobilization. Increase in the chain length of the grafted PEO resulted in significant increases in hydrophilicity and surface mobility.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820231309
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  • 10
    Electronic Resource
    Electronic Resource
    In vivo biostability and calcification-resistance of surface-modified PU-PEO-SO3 (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 1063-1073 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To examine the biostability and calcification-resistance of polyurethanes (PUs), the surface of PU was grafted with hydrophobic perfluorodecanoic acid (PFDA) (PU-PFDA), hydrophilic polyethyleneoxide (PEO) (PU-PEO1000), and further negatively charged sulfonate groups (PU-PEO1000-SO3). An in vivo animal test was conducted by subcutaneous implantation in rats during 2, 4 and 6 months. A scanning electron microscope study demonstrated that the degree of surface cracking on explanted PUs was increased in the following order: PU-PFDA 〉 PU 〉 PU-PEO1000 〉 PU-PEO1000-SO3. In the results of energy dispersive x-ray analysis and inductively coupled plasma atomic emission spectrometry, the deposition of calcium was found abundantly, but that of phosphorus was hardly in existence in all implanted PUs, suggesting that this calcium compound is not a hydroxyapatite. The calcium contents, regardless of implantation time, were also increased in the same order (PU-PFDA 〉 PU 〉 PU-PEO1000 〉 PU-PEO1000-SO3). After 6 months implantation, no severe tissue reactions were observed and calcification almost occurred on polymer surfaces in all implants. Such superior biostability and anticalcification of PU-PEO1000-SO3 might be attributed to synergistic effects of its excellent surface smoothness, sulfonate acid (SO3-) groups, nonadhesive and mobile PEO, and the high hydrophilicity and enhanced blood compatibility. Therefore, PU-PEO1000-SO3 is promising as biostable and calcification-resistant biomaterial. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820270812
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