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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of polyanhydrides: melt-polycondensation, dehydrochlorination, and dehydrative coupling (1987)
    s.l. : American Chemical Society
    Macromolecules 20 (1987), S. 705-712 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00170a001
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  • 2
    Electronic Resource
    Electronic Resource
    N-acetylglucosamine and adenosine derivatized surfaces for cell culture: 3T3 fibroblast and chicken hepatocyte response (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 801-809 
    Details
    ISSN: 0006-3592
    Keywords: 3T3 Fibroblast ; chicken hepatocytes ; cell-polymer interactions ; N-acetylglucosamine derivatized polystyrene ; hepatocytes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: 3T3 fibroblasts and primary chicken hepatocytes were cultured on derivatized polystyrene surfaces to examine the effect of cell-specific ligands on cellular morphology and growth. Surfaces were prepared by derivatizing chloromethylated polystyrene with N-acetylglucosamine (GlcNAc; recognized by the chicken asialoglycoprotein receptor) and adenosine (not recognized by adult hepatocytes). These surfaces were compared with tissue culture polystyrene (TCPS), acid-cleaned glass, and the unmodified chloromethylated polystyrene. The spreading, cytoskeletal structure and growth of the fibroblasts following attachment to these surfaces were examined. The extent of attachment, total protein levels, and DNA contents for surfaces-attached chicken hepatocytes were also measured. Fibroblast spreading was greatest on polymer surfaces derivatized with GlcNAc, whereas cytoskeletal structure and growth rate were independent of surface chemistry. Although chicken hepatocytes attached most efficiently to the GlcNAc derivatized polymer, the total protein and DNA levels of the surface-attached cells were not affected. In anticipation of the application of these polymers for cell culture and hybrid artificial organ design, the GlcNAc-derivatized polystryrene was fabricated into porous microcarriers. Fibroblasts grew avidly on the microcarriers, whereas chicken hepactocytes adhered well to the formed large aggregates arounds the microcarriers.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430815
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  • 3
    Electronic Resource
    Electronic Resource
    Interfacial polycondensation and characterization of polyphosphates and polyphosphonates (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1157-1165 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of four bisphenol A-based polyphosphates and phosphonates was accomplished. The polymerization involved a condensation between bisphenol A and a phosphorodichloridate. The heterophasic polycondensation technique was used with the aid of a phase transfer catalyst to yield molecular weights in the range of 20,000-40,000. The polymers were characterized by FT-IR, FT-NMR, and DSC. Systematic studies on the interfacial polymerization indicated that a more concentrated organic phase and a slight excess of diol favored the production of high molecular weight polymers. An optimum concentration of 5-10 mol % was observed for three different phase transfer catalysts. Kinetic studies showed that the polymerization was complete within the first 10 min. The degree of agitation was shown to be important, as the overhead mechanical stirrer was not as effective as the blender. In addition, crosslinking with pentaerythritol yielded significant increases in the molecular weights of these polymers.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290809
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  • 4
    Electronic Resource
    Electronic Resource
    Evaluation of polyphosphates and polyphosphonates as degradable biomaterials (1991)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 25 (1991), S. 1151-1167 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of polymers, bisphenol A-based poly(phosphoesters), were evaluated as degradable biomaterials. Degradation was observed for the four polymers studied under both in vitro and in vivo conditions. The rate of degradation was affected by polymer side-chain structure and correlated with the swelling behavior. The ethyl side-chain polymers absorbed more water than their phenyl counterparts. Among the sterilization methods, UV irradiation followed by antibiotic treatment was the most suitable, as steam autoclave and ethylene oxide treatments altered the properties of several of the poly(phosphoesters). Tissue response to the poly(phosphoesters) in rabbits was characterized by minor encapsulation and slight or no lymphocyte, giant cell, or macrophage activity. No evidence of edema or necrosis was found. The elastic moduli of these materials varied from 488 MPa for poly(bisphenol A-ethylphosphate) (BPA/EOP) to 627 MPa for the more rigid poly(bisphenol A-phenylphosphonate) (BPA/PP). The ultimate strength, modulus, and energy to failure of BPA/PP were lower than those of similarly compression molded high-molecular-weight poly(L-lactic acid) (PLLA).
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820250908
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  • 5
    Electronic Resource
    Electronic Resource
    Poly(L-lactic acid) foams with cell seeding and controlled-release capacity (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 30 (1996), S. 475-484 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A synthetic porous three-dimensional structure that can mimic the architecture of actual tissues, provide sustained release of nutrients or growth factors, and serve as a template for cell seeding would be an ideal substrate for tissue engineering. Poly(L-lactic acid) (PLLA) foams were fabricated for this purpose, based on the principle of phase separation from homogeneous naphthalene solutions. Complex shapes could be readily fabricated, and resulting foams had relatively uniform, open cells throughout the matrix. Densities and total pore-surface areas were in the range of 0.05-0.1 g/cm3 and 0.8-1.3 m2/g, respectively. The loss tangent of these foams ranged from 0.07 to 0.128, as measured by thermomechanical analysis. Naphthalene residue in the resulting foams went below 0.2 wt% after extensive vacuum sublimation. Feasibility of incorporating drugs or nutrients into such a highly porous structure was demonstrated by the dispersion of two model compounds, bromothymol blue (BTB) and sulforhodamine B (SD), in the matrix. Sustained release of BTB from the foam with a porosity as high as 87% was observed for more than 2 months. Alkaline phosphatase, as a model protein to be incorporated, lost approximately 30% of its bioactivity during the fabrication. As a cell-culture substrate, the PLLA foams performed as well as the flat PLLA surface in supporting the growth of rat osteosarcoma cells (ROS 17/2.8) and in maintaining their functions such as alkaline phosphatase activity and osteocalcin synthesis. UMR-106 cells cultured in the foam also expressed a higher degree of mineralization than those cultured on the flat PLLA substrate. © John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bioerodible polyanhydrides as drug-carrier matrices. I: Characterization, degradation, and release characteristics (1985)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 941-955 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polyanhydrides based on a variety of aromatic and aliphatic dicarboxylic acids were developed as bioerodible carrier matrices for controlled delivery applications. The high hydrolytic reactivity of the anhydride linkage provides an intrinsic advantage over other classes of bioerodible polymers in versatility and control of degradation rates. For example, using the poly[bis(p-carboxyphenoxy) alkane anhydrides] as models, polymers with degradation rates in the range of 10-1 to 10-4 mg/h/cm2 were obtained by changing the alkane from a methyl to a hexyl group. The polymers were characterized by infrared (IR), differential scanning calorimetry, gel permeation chromatography, and scanning electron microscopy (SEM). Near zero-order degradation kinetics were observed for the hydrophobic polyanhydrides over several months. The drug release profile of the model drug p-nitroaniline followed closely that of the degradation of injection-molded poly[bis(p-carboxyphenoxy) propane anhydride] over a period of more than 8 months. Close correlation of polymer degradation and drug release was also observed in other injection-molded samples (10% loading), suggesting a release mechanism that was dominantly degradation controlled. Degradation of these polyanhydrides was pH sensitive, being enhanced in high pH, and became more stable in acidic conditions.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820190806
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  • 7
    Electronic Resource
    Electronic Resource
    Bioerodible polyanhydrides as drug-carrier matrices. II. Biocompatibility and chemical reactivity (1986)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 51-64 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biocompatibility of bioerodible polyanhydrides and toxicology of the polymer breakdown products were assessed. Poly-[bis (p-carboxy-phenoxy) propane anhydride] (PCPP), Poly(terephthalic acid anhydride) (PTA), and their copolymers with sebacic acid were tested. The polymers did not provoke inflammatory responses in the corneas of rabbits over a six week implantation period. Subcutaneous implantation studies of PCPP in rats over a six month period showed no evidence of inflammatory cells and only slight tissue encapsulation by layers of fibroblastic cells. The degradation products of the polymers were nonmutagenic, noncytotoxic, and had a low teratogenic potential. The in vitro growth of mammalian cells on the polymers was unaffected as measured by cell morphology and cell growth rate. The chemical reactivity of the polyanhydrides with reactive model drugs, para substituted anilines, was also examined. Amides were formed when the drugs were injection molded with the polyanhydrides at 120°C. However, no reaction was observed using compression molding at room temperature. No reaction occurred between the polymer and the drug during the hydrolytic degradation of the matrix at 37°C.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820200106
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