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  • chitosan  (2)
  • hydroxyapatite  (2)
  • Hybrid materials  (1)
  • Polymer hybrids  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Preparation and characterization of covalently bonded biopolymer-polypyrrole hybrid materials (1999)
    Springer
    Journal of polymer research 6 (1999), S. 203-210 
    Details
    ISSN: 1572-8935
    Keywords: Biopolymers ; Polypyrrole ; Polymer hybrids ; Hybrid materials ; Collagen ; Chitosan
    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: Abstract The synthesis of biopolymer-polypyrrole hybrid materials that can possess electrical conducting has been the focus of our laboratory. To date, we have only obtained intimate blends that at best, display ionic bonding interactions. In this paper we report on the preparation of biopolymer-polypyrrole hybrid materials with covalent bonding between the two polymer chains. This has been achieved by preparing several functionalized pyrrole monomers, followed by covalently bonding of these monomer to the biopolymer and finally, polymerizing the pyrrole monomer. The pyrrole monomers used were 4-(3-pyrrolyl)oxobutyric acid, 4-(3-pyrrolyl)butyric acid, 3-(3-pyrrolyl)propylamine and the biopolymers were collagen and chitosan. FTIR data show the presence of covalent bonding between the two polymer chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10965-006-0089-9
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Alginate-chitosan coacervation in production of artificial seeds (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 449-454 
    Details
    ISSN: 0006-3592
    Keywords: artificial seed ; sodium alginate ; chitosan ; complex coacervation ; encapsulation ; embryoid viability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Survival of secondary embryoids of winter oilseed rape (Brassica napus ssp. oleifera cv. Primor) has been used as an assay for the development of artificial seeds involving complex coacervation of alginate (polyanion) with chitosan (polycation). Germination frequency of 100% was achieved for encapsulated embryoids when alginate formed the inner matrix and chitosan the outer layer. When the matrix makeup was reversed, there was no germination of embryoids. The artificial seeds produced were hardened in dilute alkaline solutions of NaOH and Ca(OH)2. An optimum setting time could be selected based on a quantitative measurement of resistance of hardened capsules to compression and the germination frequency of the encapsulated embryoids. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420407
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation of a chitin-apatite composite by in situ precipitation onto porous chitin scaffolds (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 41 (1998), S. 541-548 
    Details
    ISSN: 0021-9304
    Keywords: apatite ; chitin ; in situ precipitation ; hydroxyapatite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Composites of chitin with calcium phosphate were obtained by in situ precipitation of the mineral from a supersaturated solution onto chitin scaffolds. The chitin scaffolds were obtained by freeze drying to give a highly porous structure possessing a polar surface favorable for apatite nucleation and growth. The extent and arrangement of calcium phosphate deposits on the chitin and substituted chitin scaffolds were explored. Up to 55% by mass of calcium phosphate could be incorporated into chitin scaffolds. Deposits on the chitin surface were of a continuous apatite carpet nature while deposits on carboxymethylated chitin surfaces displayed a spherical morphology. Carboxymethylation of chitin exerts an overall inhibitory effect towards calcium phosphate deposition, but it provides for site-specific nucleation of the mineral phase. In situ precipitation can be an important route in the future production of various polymer-calcium phosphate composites. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 541-548, 1998.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Hydroxyapatite modified chitin as potential hard tissue substitute material (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 38 (1997), S. 235-241 
    Details
    ISSN: 0021-9304
    Keywords: hydroxyapatite ; chitin ; artificial bone ; mechanical properties ; bone composites ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Calcium hydroxyapatite (HA) powder was incorporated into chitin solutions to form an intimate mixture. Upon casting of this mixture into molds of fixed dimensions with subsequent removal of solvent, HAs containing chitin flexible plates were produced. The amount of (HA) was varied from 10 to 50% by mass of HA. The elastic modulus, yield stress, and elongation to fracture, measured at a crosshead speed of 5 mm/min, of these HAs containing chitin flexible plates were evaluated. The amount of HA in the HA incorporated chitin was found to not significantly change the elastic modulus or elongation to fracture. However, a decrease in the maximum tensile stress with an increase in the HA content was found. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 38: 235-241, 1997
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    γ Irradiation of chitosan (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 43 (1998), S. 282-290 
    Details
    ISSN: 0021-9304
    Keywords: chitosan ; γ irradiation ; films ; main chain scission ; network structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Chitosan has potential biomedical applications that may require the final products to be sterilized before use. The γ irradiation of purified and highly deacetylated chitosan fibers and films at sterilizing doses (up to 25 kGy) caused main chain scissions. The viscosity average molecular weight of the polymer decreased with increasing irradiation dose, the radiation yields of scission being 1.16 in air and 1.53 in anoxia. Preirradiation application of a negative pressure of 100 kPa disrupted the network structure, which may have contributed to the greater radiation yield obtained by chitosan fibers in anoxia. Radiation induced scission of the chitosan chains resulted in a lower glass transition temperature (Tg), indicative of higher segmental mobility. The Tg was below ambient at an irradiation dose of 25 kGy in air. Irradiation in air improved the tensile strength of the chitosan film, probably due to changes in chain interaction and rearrangement. Irradiation in anoxia did not affect film properties significantly, partly because the preirradiation application of negative pressure had a negligible effect on the structure of the chitosan film. Polymer network structure and the irradiation conditions are therefore important determinants of the extent of radiation induced reactions in chitosan. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 282-290, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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