scholarly journals A New Hyaluronan Modified with β-Cyclodextrin on Hydroxymethyl Groups Forms a Dynamic Supramolecular Network

Molecules ◽  
2019 ◽  
Vol 24 (21) ◽  
pp. 3849
Author(s):  
Jelica Kovačević ◽  
Zdeňka Prucková ◽  
Tomáš Pospíšil ◽  
Věra Kašpárková ◽  
Michal Rouchal ◽  
...  
Keyword(s):  
Click Reaction ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Supramolecular Network ◽  
Stimuli Responsive ◽  
Calorimetric Titration ◽  
Supramolecular Architectures ◽  
1H Nuclear Magnetic Resonance ◽  
Exclusion Chromatography ◽  
Chemical Stimuli

A new hyaluronan derivative modified with β-cyclodextrin units (CD-HA) was prepared via the click reaction between propargylated hyaluronan and monoazido-cyclodextrin (CD) to achieve a degree of substitution of 4%. The modified hyaluronan was characterized by 1H-nuclear magnetic resonance spectroscopy (NMR) and size exclusion chromatography. Subsequent 1H-NMR and isothermal calorimetric titration experiments revealed that the CD units on CD-HA can form virtual 1:1, 1:2, and 1:3 complexes with one-, two-, and three-site adamantane-based guests, respectively. These results imply that the CD-HA chains used the multitopic guests to form a supramolecular cross-linked network. The free CD-HA polymer was readily restored by the addition of a competing macrocycle, which entrapped the cross-linking guests. Thus, we demonstrated that the new CD-HA polymer is a promising component for the construction of chemical stimuli-responsive supramolecular architectures.

Structure of a shear-thickening polysaccharide extracted from the New Zealand black tree fern, Cyathea medullaris

2020 ◽  
Author(s):  
M Wee ◽  
M Mastrangelo ◽  
Susan Carnachan ◽  
Ian Sims ◽  
K Goh
Keyword(s):  
New Zealand ◽  
Uronic Acid ◽  
Average Molecular Weight ◽  
Shear Thickening ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Tree Fern ◽  
13C Nuclear Magnetic Resonance ◽  
Exclusion Chromatography

A shear-thickening water-soluble polysaccharide was purified from mucilage extracted from the fronds of the New Zealand black tree fern (Cyathea medullaris or 'mamaku' in Māori) and its structure characterised. Constituent sugar analysis by three complementary methods, combined with linkage analysis (of carboxyl reduced samples) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR) revealed a glucuronomannan comprising a backbone of 4-linked methylesterified glucopyranosyl uronic acid and 2-linked mannopyranosyl residues, branched at O-3 of 45% and at both O-3 and O-4 of 53% of the mannopyranosyl residues with side chains likely comprising terminal xylopyranosyl, terminal galactopyranosyl, non-methylesterified terminal glucopyranosyl uronic acid and 3-linked glucopyranosyl uronic acid residues. The weight-average molecular weight of the purified polysaccharide was ~1.9×106Da as determined by size-exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS). The distinctive rheological properties of this polysaccharide are discussed in relation to its structure. © 2014 Elsevier B.V.

Molecular and biochemical characteristics of inulosucrase InuBK from Alkalihalobacillus krulwichiae JCM 11 691

2021 ◽  
Author(s):  
Ken-ji Yokoi ◽  
Sosyu Tsutsui ◽  
Gen-ya Arakawa ◽  
Masakazu Takaba ◽  
Koichi Fujii ◽  
...  
Keyword(s):  
High Performance ◽  
Culture Medium ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Gene Encoding ◽  
Reading Frame ◽  
Exclusion Chromatography ◽  
Chain Lengths

Abstract Information about the inulosucrase of non-lactic acid bacteria is scarce. We found a gene encoding inulosucrase (inuBK) in the genome of the gram-positive bacterium Alkalihalobacillus krulwichiae JCM 11691. The inuBK open reading frame encoded a protein comprising 456 amino acids. We expressed His-tagged InuBK in culture medium using a Brevibacillus system. The optimal pH and temperature of purified InuBK were 7.0–9.0 and 50 °C–55 °C, respectively. The findings of high-performance anion-exchange chromatography, nuclear magnetic resonance spectroscopy, and high-performance size-exclusion chromatography with multi-angle laser light scattering showed that the polysaccharide produced by InuBK was an inulin with a molecular weight of 3,806, a polydispersity index (PI) of 1.047, and fructosyl chain lengths with 3–27 degrees of polymerization. The size of InuBK was smaller than commercial inulins, and the PI of the inulin that it produced was lower.

Structure of a shear-thickening polysaccharide extracted from the New Zealand black tree fern, Cyathea medullaris

2020 ◽  
Author(s):  
M Wee ◽  
M Mastrangelo ◽  
Susan Carnachan ◽  
Ian Sims ◽  
K Goh
Keyword(s):  
New Zealand ◽  
Uronic Acid ◽  
Average Molecular Weight ◽  
Shear Thickening ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Tree Fern ◽  
13C Nuclear Magnetic Resonance ◽  
Exclusion Chromatography

A shear-thickening water-soluble polysaccharide was purified from mucilage extracted from the fronds of the New Zealand black tree fern (Cyathea medullaris or 'mamaku' in Māori) and its structure characterised. Constituent sugar analysis by three complementary methods, combined with linkage analysis (of carboxyl reduced samples) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR) revealed a glucuronomannan comprising a backbone of 4-linked methylesterified glucopyranosyl uronic acid and 2-linked mannopyranosyl residues, branched at O-3 of 45% and at both O-3 and O-4 of 53% of the mannopyranosyl residues with side chains likely comprising terminal xylopyranosyl, terminal galactopyranosyl, non-methylesterified terminal glucopyranosyl uronic acid and 3-linked glucopyranosyl uronic acid residues. The weight-average molecular weight of the purified polysaccharide was ~1.9×106Da as determined by size-exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS). The distinctive rheological properties of this polysaccharide are discussed in relation to its structure. © 2014 Elsevier B.V.

Σύνθεση γραμμικών και αστεροειδών πολυμερών αποτελούμενα από συστάδες με υψηλή παράμετρο αλληλεπίδρασης Flory-Huggins χ

2020 ◽  
Author(s):  
Μαρία-Μαλβίνα Σταθουράκη
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
X Ray ◽  
X Ray Scattering ◽  
Exclusion Chromatography

Σκοπό της διατριβής αυτής αποτελεί η σύνθεση και η μελέτη της αυτοοργάνωσης γραμμικών και αστεροειδών συμπολυμερών με υψηλή παράμετρο αλληλεπιδρασης Flory-Huggins, χ. Τα πολυμερή αυτά, λόγω της μικρής αναμιξιμότητας που παρουσιάζουν τα συστατικά τους, έχουν την δυνατότητα σε μικρά μοριακά βάρη να μπορούν να σχηματίζουν πολύ μικρές και καλά καθορισμένες δομές κατά το μικροφασικό διαχωρισμό. Αρχικά, πραγματοποιήθηκε η σύνθεση των γραμμικών δισυσταδικών συμπολυμερών πολυ(2-βινυλοπυριδίνης)-b-πολυ(l-λακτιδίου) (P2VP-b-PLLA) και των τρισυσταδικών πολυ(l-λακτιδίου)-b-πολύ(διμεθυλοσιλοξάνη)-b-πολύ(l-λακτιδίου) (PLLA-b-PDMS-b-PLLA), καθώς και γραμμικών και αστεροειδών συμπολυμερών πολύ(στυρένιο)-b-πολυ(μονομεθακρυλική γλυκερόλη), PS-b-PGMA, (πολυστυρένιο)2(πολυ(μονομεθακρυλική γλυκερόλη)), (PS)2(PGMA), και (πολυστυρένιο)3(πολυ(μονομεθακρυλική γλυκερόλη)), (PS)3(PGMA), σε διάφορες αναλογίες μοριακών βαρών των συστατικών τους. Χρησιμοποιήθηκαν τεχνικές ζωντανού ανιοντικού πολυμερισμού για τη σύνθεση της P2VP, καθώς και για τη σύνθεση των αστεροειδών πολυμερών, ενώ η σύνθεση των PLLA πραγματοποιήθηκε με χρήση πολυμερισμού διάνοιξης δακτυλίου (Ring Opening Polymerization, ROP). Ο μοριακός χαρακτηρισμός των πολυμερών έγινε μέσω Χρωματογραφίας Αποκλεισμού Μεγεθών (Size Exclusion Chromatography, SEC) και Φασματοσκοπίας Πυρηνικού Μαγνητικού Συντονισμού Πρωτονίου (Nuclear Magnetic Resonance Spectroscopy, 1H-NMR). Τέλος, τίθενται τα αποτελέσματα που αφορούν τα γεωμετρικά χαρακτηριστικά (μέγεθος, μορφολογία) των περιοδικών νανοδομών που σχηματίζουν στο τήγμα τα συμπολυμερή, μέσω σκέδασης ακτίνων Χ σε μικρές γωνίες (Small-angle X-ray Scattering, SAXS).

NEW ELASTOMERIC MATERIALS FROM BIOMASS: STEREOSELECTIVE POLYMERIZATION OF LINEAR TERPENES AND THEIR COPOLYMERIZATION WITH BUTADIENE BY USING A COBALT COMPLEX WITH PHOSPHANE LIGANDS

2020 ◽  
Vol 93 (4) ◽  
pp. 605-614
Author(s):  
David Hermann Lamparelli ◽  
Veronica Paradiso ◽  
Carmine Capacchione
Keyword(s):  
Room Temperature ◽  
Cobalt Complex ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
New Materials ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Elastomeric Materials ◽  
Exclusion Chromatography ◽  
Stereoregular Polymers

ABSTRACT The polymerization of bio-renewable terpenes such as β-ocimene (O), β-myrcene (M), and β-farnesene (F) promoted by CoCl2(PCyPh2)2 (1) in combination with modified methylalumoxane at room temperature is reported. Stereoregular polymers of O, M, and F were obtained. 1 also promoted, showing good stereoselectivity, the copolymerization of O and M with butadiene (B) in a wide range of compositions by suitably varying the alimentation feed: up to 67 and 75 mol% of O and M incorporated for poly(ocimene-butadiene) and poly(myrcene-butadiene) copolymers, respectively. These new materials with elastomeric properties (glass transition temperatures observed in the range of −5.7 to −72.5 °C) were fully characterized by differential scanning calorimetry, size exclusion chromatography, and nuclear magnetic resonance spectroscopy (1H, 13C, and two-dimensional experiments).

Modification of acid hydrolysis lignin for value-added applications by micronization followed by hydrothermal alkaline treatment

Holzforschung ◽  
2015 ◽  
Vol 69 (6) ◽  
pp. 761-768 ◽  
Author(s):  
Stepan M. Krutov ◽  
Dmitry V. Evtuguin ◽  
Elena V. Ipatova ◽  
Sonia A.O. Santos ◽  
Yurii N. Sazanov
Keyword(s):  
Value Added ◽  
Alkaline Treatment ◽  
Raw Material ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Ionization Mass ◽  
Hydrolysis Lignin ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
L1 And L2

Abstract Technical hydrolysis lignin (THL) was micronized by grinding in a rotary-jet mill to obtain a fraction of approximately 5 mm. Both initial and milled THLs were liquefied by thermal alkaline treatment at 220°C for 2 h. Upgraded THLs that were nonmilled (L1) and milled (L2) were desalted by treatment with cation-exchanged resin and were dried. Micronization affected the course of hydrothermal alkaline treatment and the structure and composition of the obtained lignin. Thus, L2 contained much less concomitant polysaccharides and extractives than L1 and was more condensed. The molecular weights of L1 and L2 were 1100 and 1000 Da, respectively, as determined by size-exclusion chromatography. Structural characterization carried out by employing tandem electrospray ionization-mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy revealed that small amounts of β-O-4 (∼6 mol.%), β-5, and β-β structures still remained in L1 and L2. Overall, upgraded lignins are oligomers (trimers-pentamers) with highly degraded propane chains and possess polyconjugated condensed aromatic structures. Upgraded THL seems to be a promising raw material for polymeric formulations.

Synthesis and Characterization of Poly (styrene-co-butyl acrylate)/Silica Aerogel Nanocomposites by in situ AGET ATRP: Investigating Thermal Properties

2017 ◽  
Vol 36 (10) ◽  
pp. 955-962 ◽  
Author(s):  
Khezrollah Khezri ◽  
Yousef Fazli
Keyword(s):  
Molecular Weight ◽  
Butyl Acrylate ◽  
Silica Aerogel ◽  
Size Exclusion ◽  
Proton Nuclear Magnetic Resonance ◽  
Molar Ratio ◽  
Resonance Spectroscopy ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Exclusion Chromatography

AbstractHydrophilic silica aerogel nanoparticles surface was modified with hexamethyldisilazane. Then, the resultant modified nanoparticles were used in random copolymerization of styrene and butyl acrylate via activators generated by electron transfer for atom transfer radical polymerization. Conversion and molecular weight determinations were performed using gas and size exclusion chromatography respectively. Addition of modified nanoparticles by 3 wt% results in a decrease of conversion from 68 to 46 %. Molecular weight of copolymer chains decreases from 12,500 to 7,500 g.mol–1 by addition of 3 wt% modified nanoparticles; however, PDI values increase from 1.1 to 1.4. Proton nuclear magnetic resonance spectroscopy results indicate that the molar ratio of each monomer in the copolymer chains is approximately similar to the initial selected mole ratio of them. Increasing thermal stability of the nanocomposites is demonstrated by thermal gravimetric analysis. Differential scanning calorimetry also shows a decrease in glass transition temperature by increasing modified silica aerogel nanoparticles.

scholarly journals Synthesis and characterization of amphiphilic graft copolymers of poly(1,3 dioxolane) macromonomers with styrene and methyl methacrylate

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Hayet Bendaikha ◽  
Gérald Clisson ◽  
Abdelouahad Khoukh ◽  
Jeanne François ◽  
Seghier Ould Kada
Keyword(s):  
Methyl Methacrylate ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Molecular Weights ◽  
Molar Ratios ◽  
H Nmr ◽  
Amphiphilic Graft Copolymers ◽  
Exclusion Chromatography ◽  
Cationic Ring Opening Polymerization

AbstractMethacrylate-terminated Poly(1,3 dioxolane) (PDXL) macromonomers were synthesized by cationic ring-opening polymerization in the presence of 2- hydroxypropyl methacrylate (2-HPMA) as transfer agent. Molecular weights, polydispersity index and functionality of the PDXL macromonomers were evaluated by size exclusion chromatography (SEC) and 1H nuclear magnetic resonance spectroscopy (1H-NMR). Copolymerizations of PDXL macromonomers, of different molecular weights, with styrene (St) and methyl methacrylate (MMA) were carried out using various feed molar ratios. The resulting polymers confirmed the grafting of PDXL with PS and PMMA by SEC and 1H-NMR Monomer reactivity ratios between the macromonomers and the comonomers were estimated from the copolymerization results. Macromonomer reactivity depends on the comonomer considered. Glass transition temperatures of the copolymers were found to decrease with an increase in the amount of PDXL in the copolymers. The values of Tg depend on the composition and the size of the PDXL grafts.

Star-shaped poly(2-ethyl-2-oxazoline) featuring a porphyrin core: synthesis and metal complexation

e-Polymers ◽  
2015 ◽  
Vol 15 (4) ◽  
pp. 227-235 ◽  
Author(s):  
Tobias Rudolph ◽  
Sarah Crotty ◽  
Ulrich S. Schubert ◽  
Felix H. Schacher
Keyword(s):  
Metal Ion ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Visible Spectroscopy ◽  
Central Cavity ◽  
One Pot ◽  
Ionization Time ◽  
Flight Mass Spectrometry ◽  
Exclusion Chromatography ◽  
Porphyrin Core

AbstractWe demonstrate the synthesis of star-shaped poly(2-ethyl-2-oxazoline) featuring a porphyrin core starting from alkyne-functionalized porphyrin ([TPP-TB]4) and azide-functionalized poly(2-ethyl-2-oxazoline) (PEtOx-N3) via copper-catalyzed azide-alkyne cycloaddition (CuAAC). The porphyrin core was further utilized for the complexation of either copper or iron within the central cavity. The obtained materials were investigated using a combination of nuclear magnetic resonance spectroscopy, fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, size-exclusion chromatography, and matrix assisted laser desorption/ionization time-of-flight mass spectrometry. In the case of copper, the inclusion of the metal ion was achieved in a one-pot reaction during the CuAAC reaction for attaching the PEtOx-N3 arms.

scholarly journals Structural Features and Rheological Properties of a Sulfated Xylogalactan-Rich Fraction Isolated from Tunisian Red Seaweed Jania adhaerens

2020 ◽  
Vol 10 (5) ◽  
pp. 1655 ◽  
Author(s):  
Faiez Hentati ◽  
Cédric Delattre ◽  
Christine Gardarin ◽  
Jacques Desbrières ◽  
Didier Le Cerf ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Flow Characteristics ◽  
Structural Features ◽  
Sulfated Polysaccharide ◽  
Size Exclusion ◽  
Random Coil ◽  
Precipitation Process ◽  
Resonance Spectroscopy ◽  
Exclusion Chromatography ◽  
Average Molecular Masses

A novel sulfated xylogalactan-rich fraction (JSP for J. adhaerens Sulfated Polysaccharide) was extracted from the red Tunisian seaweed Jania adhaerens. JSP was purified using an alcoholic precipitation process and characterized by Attenuated Total Reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR), high-pressure size exclusion chromatography (HPSEC) with a multi-angle laser light scattering (MALLS), gas chromatography coupled to mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR, 1D and 2D). JSP was then evaluated regarding its physicochemical and rheological properties. Results showed that JSP was mainly composed of an agar-like xylogalactan sharing the general characteristics of corallinans. The structure of JSP was mainly composed of agaran disaccharidic repeating units (→3)-β-d-Galp-(1,4)-α-l-Galp-(1→)n and (→3)-β-d-Galp-(1,4)-3,6-α-l-AnGalp-(1→)n, mainly substituted on O-6 of (1,3)-β-d-Galp residues by β-xylosyl side chains, and less with sulfate or methoxy groups. (1,4)-α-l-Galp residues were also substituted by methoxy and/or sulfate groups in the O-2 and O-3 positions. Mass-average and number-average molecular masses (Mw) and (Mn), intrinsic viscosity ([η]) and hydrodynamic radius (Rh) for JSP were, respectively, 8.0 × 105 g/mol, 1.0 × 105 g/mol, 76 mL/g and 16.8 nm, showing a flexible random coil conformation in solution. The critical overlap concentration C* of JSP was evaluated at 7.5 g/L using the Williamson model. In the semi-diluted regime, JSP solutions displayed a shear-thinning behavior with a great viscoelasticity character influenced by temperature and monovalent salts. The flow characteristics of JSP were described by the Ostwald model.

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