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  • 1
    Electronic Resource
    Electronic Resource
    Polymerization reaction with diphenylphosphoryl azide. Preparation of sequential polypeptides by direct polycondensation of peptides (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1799-1809 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Various kinds of sequential polypeptides were prepared by direct polymerization of peptides in the presence of diphenylphosphoryl azide (DPPA). Typically, polymerization reactions were carried out as follows; monomer peptide concentration: 300 mg/0,6 mL of DMSO (or some other solvent); amount of DPPA: 1,3 mol/mol peptide; amount of triethylamine: 2,3 mol/mol peptide (+1,0 mol/mol peptide in case of peptide hydrochloride); reaction time: 2 days at room temperature. Molecular weights of the resulting sequential polypeptides were estimated from their intrinsic viscosities in dichloroacetic acid and SDS-polyacrylamide gel electrophoresis; they range from 4 000 to 30 000. The purity of the sequential polypeptides was confirmed by IR, elemental analysis and optical rotation measurements of their acid total hydrolysates.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920814
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  • 2
    Electronic Resource
    Electronic Resource
    Polymerization reaction with diphenylphosphoryl azide. Preparation of polyamides, polyureas and polyurethanes (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1811-1820 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The preparation of various polyamides, polyureas and polyurethanes by polymerization reactions with diphenylphosphoryl azide (DPPA) was investigated. Various polyamides were obtained very conveniently by polymerization of aminocarboxylic acids or copolymerization of dicarboxylic acids and diamines. Polyureas were mainly obtained by conversion of dicarboxylic acids to acyl azides with DPPA and then to isocyanates, followed by copolymerization of these diisocyanates with diamines. Further, the polymerization of some aminocarboxylic acids that have an amino group of low nucleophilicity (such as p-aminobenzoic acid) was found to give polyureas instead of polyamides by direct polymerization. Polyurethanes were also obtained from dicarboxylic acids and diols through the Curtius rearrangement of acyl azides, similarly as in the polyurea preparations. The products were identified with the help of IR spectra and elemental analyses, and their molecular weights were evaluated viscometrically.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920815
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  • 3
    Electronic Resource
    Electronic Resource
    Polymerization reaction with diphenylphosphoryl azide. Preparation of poly(α-amino acid)s by direct polycondensation of α-amino acids (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1789-1798 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polypeptides can be prepared by stirring an amino acid solution in the presence of diphenylphosphoryl azide (DPPA) and an adequate tertiary amine. Generally, 1,3 mol of DPPA and 2,3 mol of triethylamine per mol of amino acid gave the best result. Polymerization of various amino acids (Gly, Ala, Leu, Phe, Met, Glu(OBzl), Glu(OMe), Cys(Bzl), Ser(Bzl), His(Bzl), Lys(Z), Arg(Tos), Arg(NO2), Arg(Mts), etc.; cf. Tab. 2) in dimethyl sulfoxide, N,N-dimethylformamide, 1,4-dioxane, pyridine, etc. gave the corresponding polypeptides with molecular weights as estimated from their intrinsic viscosities between 3 000 and 16 000, in reasonable yields. The purity of the resulting polypeptides was confirmed by IR, elemental analysis and optical rotation measurements of their acid total hydrolysates.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920813
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  • 4
    Electronic Resource
    Electronic Resource
    Graft copolymers having hydrophobic backbone and hydrophilic branches. X. Preparation and properties of water-dispersible polyanionic microspheres having poly(methacrylic acid) branches on their surfacesFor Part IX, see Riza et al.8 (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1219-1225 
    Details
    ISSN: 0887-624X
    Keywords: macromonomer ; graft copolymer ; dispersion copolymerization ; anionic microsphere ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The free radical copolymerization of poly(t-butyl methacrylate) (PBMA) macromonomer with styrene in ethanol give monodispersed microspheres with 0.8-1.6 μm diameter. The resulting microspheres were treated with HCl solution to convert into anionic microspheres having poly(methacrylic acid) chains. ESCA analysis of the microsphere surface suggested that PBMA chains were favorably located on the surface of the microspheres. The particle size of the microspheres decreased with increasing molecular weight and concentration of the macromonomer. Water dispersibilities of the microspheres were evaluated by measuring the relative turbidity of the suspension of microspheres as a function of pH. The results show that they were strongly dependent on pH. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330804
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  • 5
    Electronic Resource
    Electronic Resource
    Preparation of an α-cyclodextrin-linked chitosan derivative via reductive amination strategy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1965-1968 
    Details
    ISSN: 0887-624X
    Keywords: chitosan ; α-cyclodextrin ; reductive amination ; host-guest complex ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Monolayer formation of chitin derivatives containing PMMA side-chains (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 35 (1994), S. 303-307 
    Details
    ISSN: 0959-8103
    Keywords: monolayer formation ; PMMA-grafted chitin derivative ; phase transition ; accessible monolayer to lysozyme ; 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 monolayer behaviour of poly(methyl methacrylate) (PMMA)-grafted chitin derivatives was studied on an air-water interface by measuring surface pressure-area isotherms. The formation of a stable monolayer indicates the well-defined packing and orientation of the chitin derivative, which can be regulated by the main-chain length under appropriate experimental conditions. The isotherms exhibit a transition point from a liquid expanded phase to a condensed phase at a surface pressure of approximately 15mN/m for almost all monolayers examined. The transition pressure decreases with increase of temperature from 10 to 20°C. The properties of the sub-phase affected the formation of a monolayer greatly. The collapse of a surface film takes place at lower pressure on the sub-phase of a 0.1 M NaCI solution. After introducing lysozyme at a concentration at 2.4 × 10-8M to the sub-phase, the monolayer showed an extensively expanded phase with a longer transition region. This indicates that the monolayer was degraded by the lysozyme, resulting in a disordered structure. The results are contrasted with those of an aqueous phase where N-acetylglucosamine residues may be inaccessible to lysozyme so that the degradation of the chitin derivative occurs at a very slow rate.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210350401
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  • 7
    Electronic Resource
    Electronic Resource
    Stabilization of photo-induced radicals in hematoporphyrin-IX-doped chitosan film (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 36 (1995), S. 365-372 
    Details
    ISSN: 0959-8103
    Keywords: chitosan film ; doping ; hematoporphyrin-IX ; photo-induced radicals ; electron spin resonance ; induced circular dichroism ; 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: Induction and stabilization of free radicals were investigated in hematoporphyrin-IX (Hp)-doped chitosan (Hp-Ch) film by electron spin resonance (ESR) following photo-irradiation. Induced radicals were more stable in chitosan and 6-O-carboxymethyl chitin films than in carboxymethyl cellulose and sodium alginate films. Hydroxyl groups on D-glucosamine residues in chitosan are suggested as participating in accepting radicals, since spin trapping was absorbed in ESR spectra of Hp-Ch film by the use of oxygen sensitive spin trapping reagent. An induced circular dichroism spectrum was observed only for Hp-doped chitosan film over a range 360-450 nm among seven pairs of polymers and dyes; it is suggested that Hp molecules are arranged parallel along the carbohydrate backbone of chitosan, resulting in the highest acceptance of photo-induced radicals in the polymer film.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1995.210360409
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  • 8
    Electronic Resource
    Electronic Resource
    Endothelial cell responses to chitin and its derivatives (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 43 (1998), S. 469-472 
    Details
    ISSN: 0021-9304
    Keywords: angiogenesis ; cell proliferation ; chitin derivatives ; cytokine production ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effects of chitin and its derivatives on the proliferation of human umbilical vein endothelial cells (HUVECs) and on the production of cytokines were examined in vitro. Chitin and its derivatives had no effect on the proliferation of cultured HUVECs. N-Sulfonated 70% deacetylated chitin (S-DAC70) stimulated the production of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α from HUVECs. Compared to S-DAC70, the other materials tested in the present study showed less effect in the stimulation of IL-8 and TNF-α production and had no effect in the stimulation of IL-1β and IL-6 production. These results indicated that S-DAC70 affects HUVECs function but not proliferation. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 469-472, 1998
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Macrophage activation with multi-porous beads prepared from partially deacetylated chitin (1986)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 1359-1372 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of multi-porous beads prepared from 80% deacetylated chitin on the activation of mouse peritoneal macrophages was examined. Deacetylated chitin bead (DAC-bead) preparations were shown to activate macrophages for tumoricidal activity depending on the increasing concentration of acetic acid used for the pretreatment of beads. The large DAC-bead was more susceptible to treatment with acetic acid than small DAC-bead, and showed more potent capacity for the activation of macrophages under the same pretreatment conditions with acetic acid. Reacetylated bead preparations, on the other hand, showed less activities. In addition, DAC-bead pretreated with acetic acid stimulated macrophages to produce interleukin 1. The possibilities of multi-porous beads as cancer chemotherapeutic-carrier were examined by the method of column chromatography and of in vitro antitumor experiment. Forty-four percent of adriamycin adsorbed on the surface of and in bead was released within the first 60 min. of elution, and then adriamycin was released more slowly in proportion to the elution time. Antitumor activity of adriamycin-adsorbed bead was less effective than that of free adriamycin if they were compared on the basis of total content of adriamycin.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820200910
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