| 1. |
- Tahir, M. Nazir, et al.
(författare)
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Alkynyl Ethers of Glucans : Substituent Distribution in Propargyl-, Pentynyl- and Hexynyldextrans and -amyloses and Support for Silver Nanoparticle Formation
- 2010
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Ingår i: Macromolecular Chemistry and Physics. - : Wiley. - 1022-1352 .- 1521-3935. ; 211:15, s. 1648-1662
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Tidskriftsartikel (refereegranskat)abstract
- Alkynyldextrans with a DS in the range 0.1-1.67 have been prepared as reactive intermediates for further polymer-analogous functionalisation.. DS and substituent distribution were determined by GLC and GLCMS after hydrolysis and acetylation, or methanolysis and trimethylsilylation. Reactivity was in the order O-2 > O-4 >= O-3 with pronounced differences in the distinct patterns for propargyl ethers and its higher homologous. A large deviation from a random substituent distribution was observed. Propargyldextrans were not stable during long-time storage in the solid state, while terminal pentynyl and hexynyl ethers are. Pentynyldextrans showed structure formation of various geometries. They bound silver efficiently, yielding silver nanoparticles by reduction.
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| 2. |
- Tahir, M. Nazir, et al.
(författare)
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Introduction of various functionalities into polysaccharides using alkynyl ethers as precursors : Pentynyl dextrans
- 2012
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 88:1, s. 154-164
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Tidskriftsartikel (refereegranskat)abstract
- Following the concept of using O-alkynyl glycans as key precursors of functional polysaccharides. dextran derivatives with nearly the same distritbution pattern, but various functional groups - for common (bio)conjugation reactions, molecular recognition, and antioxidant activity - have been prepared. Pentynyl dextran well characterized with respect to the degree of substitution (DS 0.43) and the distribution of alkynyl groups to the various OH of the glucosyl unit, was further modified by 1,3-dipolar cycloaddition of various functionalized azides, thus introducing amino, hydroxy, thiol, and carboxyl groups with good to quantitative yield. Besides these functional groups, biotin and tocopherol were introduced with about 60% conversion of alkyne groups. Biotinylated dextran was demonstrated to bind specifically to fluorophor-labeled streptavidin, while glucose linked tocopherol did not show loss of antioxidant activity. Formation of triazole derivatives was proved by ATR-IR and NMR spectroscopy, and after methanolysis of the dextran, by ESI mass spectrometry. Degree of conversion was estimated from H-1 NMR spectra, decrease of pentynyl groups in the product mixture analyzed by GLC, and elemental analysis.
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