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  • 1. Cuers, Julia
    et al.
    Unterieser, Inga
    Burchard, Walther
    Adden, Roland
    Rinken, Marian
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Simultaneous determination of substituent patterns in partially acid hydrolyzed O-Me/O-Me-d(3)-cellulose and quantification of the obtained oligomers by HPLC-ESI-MS2012In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 348, p. 55-63Article in journal (Refereed)
    Abstract [en]

    Substituent patterns in oligosaccharide derivatives obtained from methyl cellulose were determined up to DP10 by electrospray ionization mass spectrometry employing separation of the oligomer fractions by HPLC. Oligosaccharides were labeled with meta-aminobenzoic acid after perdeuteromethylation and partial hydrolysis of methyl cellulose, enabling simultaneous quantification according to DP by HPLC/UV. Control of the HPLC-method was performed with a defined oligomer mixture obtained from beta-cyclodextrin. Results from LC-ESI-MS are discussed in comparison with those from syringe pump injection and compared to a calculated pattern for a random distribution. Programing of instrumental parameters optimized for each DP and avoidance of competition of successively eluting analytes in the electrospray process allowed extension of the established method for determination of the substitution pattern of cellulose derivatives along the polymer chain from DP5 to DP10 and thus a significant gain of information.

  • 2. Fiege, Kathrin
    et al.
    Luensdorf, Heinrich
    Atarijabarzadeh, Sevil
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Cyanoethylation of the glucans dextran and pullulan: Substitution pattern and formation of nanostructures and entrapment of magnetic nanoparticles2012In: Beilstein Journal of Organic Chemistry, ISSN 2195-951X, E-ISSN 1860-5397, Vol. 8, p. 551-566Article in journal (Refereed)
    Abstract [en]

    Cyanoethylglucans with a degree of substitution in the range of 0.74 to 2.40 for dextran and 0.84 to 2.42 for pullulan were obtained by Michael addition of acrylonitrile to the glucans under various conditions. Products were thoroughly characterized, comprising elementary analysis, NMR and ATR-IR spectroscopy, and analysis of the substituent distribution in the glucosyl units by GC-FID and GC-MS of the constituting monosaccharide derivatives. Nanostructuring of the highly substituted cyanoethylpolysaccharides was performed by dialysis against a non-solvent. In the presence of ferromagnetic iron-oxide nanoparticles, multicore cyanoethylglucan-coated ferromagnetic nanoparticles were formed by selective entrapment. The specific interaction between cyano groups and iron could be proven. The size distribution and morphology of the nanoparticles were analyzed by dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy-filtered transmission electron microscopy (EF-TEM) with parallel electron energy loss spectroscopy (PEELS).

  • 3.
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Mass Spectrometric Characterization of Oligo- and Polysaccharides and Their Derivatives2012In: Mass Spectrometry Of Polymers - New Techniques / [ed] Hakkarainen, M, Springer Berlin/Heidelberg, 2012, p. 105-174Chapter in book (Refereed)
    Abstract [en]

    Mass spectrometry has become a key technique for the structural analysis of carbohydrates. Due to their special properties and requirements carbohydrates and especially chemically modified carbohydrates occupy a position between biopolymers and synthetic polymers. Charged analytes can be obtained by adduct formation with appropriate small ions or by various labeling procedures. Besides molecular mass profiling, tandem mass spectrometry can give more detailed structural information including sugar constituents, sequence and interresidue linkage positions, and some information on stereochemistry. Substitution patterns of polysaccharide derivatives are also studied by ESI IT-MS and MALDI ToF-MS. In this review, ion formation of carbohydrates, their chemical modification, fragmentation pathways of various analyte species, and the applicability of MS for quantitative evaluations are discussed. Mainly ESI applications are presented, but where of general significance MALDI-MS applications are also outlined. Examples of application are given, excluding the well-reviewed area of biologically important O- and N-linked glycans. Molecular mass determination and structural analysis of heteroglycans are followed by examples of cellulose and starch derivatives.

  • 4. Tahir, M. Nazir
    et al.
    Bork, Christian
    Risberg, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Horst, Jennifer C.
    Komoss, Christina
    Vollmer, Antje
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Alkynyl Ethers of Glucans: Substituent Distribution in Propargyl-, Pentynyl- and Hexynyldextrans and -amyloses and Support for Silver Nanoparticle Formation2010In: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 211, no 15, p. 1648-1662Article in journal (Refereed)
    Abstract [en]

    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.

  • 5. Tahir, M. Nazir
    et al.
    Lämmerhardt, Nico
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Introduction of various functionalities into polysaccharides using alkynyl ethers as precursors: Pentynyl dextrans2012In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 88, no 1, p. 154-164Article in journal (Refereed)
    Abstract [en]

    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.

  • 6. Tahir, Muhammad Nazir
    et al.
    Adnan, Ahmad
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Stability of lipase immobilized on O-pentynyl dextran2012In: Bioprocess and biosystems engineering (Print), ISSN 1615-7591, E-ISSN 1615-7605, Vol. 35, no 4, p. 535-544Article in journal (Refereed)
    Abstract [en]

    O-Pentynyl dextran (PyD), an amphiphilic polysaccharide derivative with a degree of substitution (DS) of 0.43 was compared with ion exchange resins Lewatit VP OC 1600, Amberlite XAD 761 and Duolite A568 for immobilization of Lipase from Rhizopus arrhizus by adsorption method. The immobilized enzymes were employed for esterification of octanoic acid with geraniol in n-hexane as model reaction. PyD showed higher lipase adsorption and with 249 mu mol min(-1) g(-1) significant higher esterification activity than the other supports (67-83 mu mol min(-1) g(-1)). Biocatalysts from all types of supports except PyD became completely inactive within 8 weeks storing at -10 A degrees C while lipase immobilized on PyD retained its full esterification activity for at least 14 weeks. In repeated use, yield decreased rapidly after two cycles for all supports except for PyD. For this biopolymeric support, constantly 90% yield was achieved even after eight cycles, when the biocatalyst was washed with n-hexane and water and then freeze-dried. To achieve this yield, prolonged reaction times were required, partly on the account of an increasing delay period, probably to adapt active conformation, until the reaction starts.

  • 7. Unterieser, Inga
    et al.
    Cuers, Julia
    Voiges, Kristin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Enebro, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Quantitative aspects in electrospray ionization ion trap and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of malto-oligosaccharides2011In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 25, no 15, p. 2201-2208Article in journal (Refereed)
    Abstract [en]

    Mass spectrometry is widely applied in carbohydrate analysis, but still quantitative evaluation of data is critical due to different ionization efficiencies of the constituents in a mixture. Different size and chemical structure of the analytes cause their uneven distribution in droplets (electrospray ionization, ESI) or matrix spots (matrix-assisted laser desorption/ionization, MALDI). In addition, instrumental parameters affect final ion yields. In order to study and optimize the latter, an equimolar mixture of malto-oligosaccharides (DP1-6) was analyzed using varying target masses for ESI as well as different matrices and laser power for MALDI. The sodium adducts and derivatives for positive ion mode (hydra-zones with Girard's T Reagent, GT) and negative ion mode (reductively aminated with o-aminobenzoic acid, oABA) were studied. Negatively charged oABA-labeled malto-oligosaccharides turned out to be unsuitable for quantification of the malto-oligomeric composition. Best agreement was achieved when applying target masses in the range of the highest homolog in the mixture in electrospray ionization ion trap (ESI-IT) (1-2% deviation with GT label or as Na(+) adducts). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) gave best results when the laser power was adjusted significantly over the desorption/ionization threshold (1% deviation with GT label). Both parameters show significant influence on the determined oligomeric composition. Consequently, estimation and even quantitative determination of amounts of oligosaccharides in a mixture can be achieved when the analytes are labeled and the proper instrumental parameters are used.

  • 8. Unterieser, Inga
    et al.
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Labeling of oligosaccharides for quantitative mass spectrometry2011In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 346, no 1, p. 68-75Article in journal (Refereed)
    Abstract [en]

    Quantitative analysis of oligosaccharide mixtures and their derivatives by electrospray ionization mass spectrometry (ESI MS) is challenging, for example, due to different affinities of the analytes to alkali ions. To overcome this source of discrimination and to enhance signal intensity, labeling studies with cellobiose as model compound were performed with the goal to develop a rapid, easy, and robust method. Hydrazone formation with the permanently charged Girard's T reagent as well as reductive amination with five different charge providing amines were studied under various conditions. In both reaction types, the removal of water turned out to be the critical step because only under these conditions are the reactions pushed to completion. By working with only a slight excess of reagents, no purification is necessary to achieve excellent signal/noise ratios, avoiding further sources of discrimination. Comparing various reducing agents with respect to their selectivity and stability in the acidic reaction medium, 2-picoline borane turned out to be superior to the commonly used sodium cyanoborohydride. Thus, by replacement of the toxic NaCNBH3 by the more selective and stable, non-toxic 2-picoline borane, complete reductive amination with low amounts of reagents and without unlabeled alditol formation was achieved with o-aminobenzoic acid, a useful reagent for ESI MS in negative mode. For MS in positive mode Girard's T derivatization was very suitable.

  • 9. Voiges, Kristin
    et al.
    Adden, Roland
    Rinken, Marian
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Critical re-investigation of the alditol acetate method for analysis of substituent distribution in methyl cellulose2012In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, no 3, p. 993-1004Article in journal (Refereed)
    Abstract [en]

    The alditol acetate method is a common procedure for sugar analysis, also applied to determine the substituent distribution in monomer units of polysaccharide ethers like methyl cellulose by gas liquid chromatography. Consisting of several preparation and work-up steps this procedure is both time consuming and prone to side reactions that promote discrimination of single constituents, especially when no peralkylation step is performed prior to hydrolysis. As a consequence results scatter in dependence on individual treatment and conditions. In the context of this work these critical points were overcome by strict but simplified work-up procedures and using acid instead of alkaline catalyzed acetylation. Under the acidic conditions the tedious removal of borate is no longer necessary and a reduced time requirement was achieved as well as good reproducibility. Comparison with independent reference methods excluded a systematic error of the method and confirmed the results obtained. Without peralkylation, i.e. in the presence of free hydroxyl groups, another fast modification of the method using DMSO as solvent, no removal of borate, and 1-methylimidazole as catalyst for acetylation was found to produce a systematic error.

  • 10. Vollmer, Antje
    et al.
    Voiges, Kristin
    Bork, Christian
    Fiege, Kathrin
    Cuber, Katja
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Comprehensive analysis of the substitution pattern in dextran ethers with respect to the reaction conditions2009In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 395, no 6, p. 1749-1768Article in journal (Refereed)
    Abstract [en]

    Dextrans from Leuconostoc ssp., alpha-1,6-linked glucans branched at O-3, were O-methylated in DMSO with lithium dimsyl and methyl iodide under various conditions. Methyl substituent distribution was comprehensively studied in the terminal, internal, and branched glucosyl units and along and over the dextran macromolecules. The order of reactivity was O-2>O-4 >= O-3. The methyl pattern in the glucosyl units significantly deviates from a random distribution with enhanced amounts of un- and trisubstituted moieties. This deviation was found to proceed on macromolecular level by means of ESI-MS of perdeuteromethylated and partially depolymerized methyl dextrans. Heterogeneity was much more pronounced than for methyl amylose prepared under comparable conditions. DS gradients in and over the material are discussed with respect to dextran structure and the mechanism of Li dimsyl alkylation. For comparison, cyanoethyl dextrans were prepared by sodium hydroxide catalyzed addition of acrylonitrile. Monomer analysis of cyanoethyl dextrans revealed that this thermodynamically controlled reaction gave a random substitution pattern with 48% of cyanoethyl groups at O-2, 33% at O-4, and 19% at O-3.

  • 11.
    Zhang, Yujia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Reactivity investigation of glucomannan from spruce2013Conference paper (Refereed)
  • 12.
    Zhang, Yujia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers, Sweden.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers, Sweden.
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Tech Univ Carolo Wilhelmina Braunschweig, Germany.
    Reactivity investigation of glucomannan from spruce2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247, no 113-CELLArticle in journal (Other academic)
  • 13.
    Zhang, Yujia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Mischnick, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Technische Universität Braunschweig, Germany .
    Relative reactivities in the O-methylation of glucomannans: the influence of stereochemistry at C-2 and the solvent effect2015In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 402, p. 172-179Article in journal (Refereed)
    Abstract [en]

    The main hemicellulose in softwood, glucomannan (GM), structurally resembles cellulose but has quite different physical and chemical properties. In addition to branching and original acetylation, the only other difference between these two beta-1,4-linked glycans is the configuration at C-2 in approximately 80% of the sugar residues. In contrast to glucose, the 2-OH in mannose has an axial orientation. The influence of this stereochemistry on the relative reactivities of glucosyl compared to mannosyl units in methylation reactions are studied in this work. Glucomannan isolated from spruce (SGM) and commercially available konjac glucomannan (KGM) was methylated in DMSO/Li-dimsyl/MeI and water/NaOH/MeI system, respectively. In the early stage of the reaction, the glucose part of the SGM achieved slightly higher DS values than the mannose residues, but the overall relative rate constants were close to 1:1. The order of reactivities in glucose was k(2) > k(3) > k(6) and k(3) > k(2) > k(6) for mannose (in DMSO/Li-dimsyl/MeI). The rate constants did not remain constant, but k(3) decreased when k(2) increased for both epimeric sugars. In water/NaOH/MeI, the methylation of the primary 6-OH was much more pronounced with an order of reactivity of O-6 > O-2 > O-3 for mannose and O-2 > O-6 > O-3 for glucose. The results are discussed with respect to the OH-acidity and the stereoelectronic, sterical, and solvent effects.

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