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).

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 Novel Biodegradable Polyanhydrides Based on Betulin Disuccinate and Sebacic Acid for Medical Purpose

Proceedings ◽  
2020 ◽  
Vol 67 (1) ◽  
pp. 17
Author(s):  
Daria Niewolik ◽  
Barbara Bednarczyk-Cwynar ◽  
Piotr Ruszkowski ◽  
Katarzyna Jaszcz
Keyword(s):  
Drug Delivery ◽  
Cell Lines ◽  
Hydrolytic Degradation ◽  
Sebacic Acid ◽  
Size Exclusion ◽  
Scanning Calorimetry ◽  
Melt Polycondensation ◽  
Wide Range ◽  
The Us ◽  
Exclusion Chromatography

The paper describes synthesis and the characterization of novel biodegradable betulin-based polyanhydrides, exhibiting anti-cancer activity. Polyanhydrides were obtained by a melt polycondensation of a disuccinate betulin (3,28-di-O-succinyl betulin) and sebacic acid with the use of acetic anhydride. Mentioned polyanhydrides were then thoroughly characterized by 1H NMR and 13C NMR, size exclusion chromatography, differential scanning calorimetry and FT-IR spectroscopy. The content of sebacic acid in obtained copolymers was from 20 to 80 wt%. The use of sebacic acid as a comonomer increases the crystallinity of polymers. Under physiological conditions copolymers undergo hydrolytic degradation to betulin disuccinate, whose biological activity is known and confirmed and to sebacic acid approved by the US Food and Drug Administration (FDA) for use in drug delivery systems. Polyanhydrides were also tested for cytostatic activity against a wide range of cancer cell lines (HeLa, A-549, U-87MG, KB and HepG2), proving its efficiency in inhibiting the growth of selected cell lines. Obtained polymers can be used as carriers in drug delivery system, in form of microspheres. Microspheres with diameter within the range of Dn = 15–30 µm were prepared by using emulsion (O/W) solvent evaporation method.

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.

scholarly journals Effect of Posttranslational Modifications on the Structure and Activity of FTO Demethylase

2021 ◽  
Vol 22 (9) ◽  
pp. 4512
Author(s):  
Michał Marcinkowski ◽  
Tomaš Pilžys ◽  
Damian Garbicz ◽  
Jan Piwowarski ◽  
Damian Mielecki ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Size Exclusion Chromatography ◽  
Posttranslational Modifications ◽  
Size Exclusion ◽  
Saxs Data ◽  
Wide Range ◽  
Exclusion Chromatography ◽  
Demethylase Activity ◽  
Structure And Activity

The FTO protein is involved in a wide range of physiological processes, including adipogenesis and osteogenesis. This two-domain protein belongs to the AlkB family of 2-oxoglutarate (2-OG)- and Fe(II)-dependent dioxygenases, displaying N6-methyladenosine (N6-meA) demethylase activity. The aim of the study was to characterize the relationships between the structure and activity of FTO. The effect of cofactors (Fe2+/Mn2+ and 2-OG), Ca2+ that do not bind at the catalytic site, and protein concentration on FTO properties expressed in either E. coli (ECFTO) or baculovirus (BESFTO) system were determined using biophysical methods (DSF, MST, SAXS) and biochemical techniques (size-exclusion chromatography, enzymatic assay). We found that BESFTO carries three phosphoserines (S184, S256, S260), while there were no such modifications in ECFTO. The S256D mutation mimicking the S256 phosphorylation moderately decreased FTO catalytic activity. In the presence of Ca2+, a slight stabilization of the FTO structure was observed, accompanied by a decrease in catalytic activity. Size exclusion chromatography and MST data confirmed the ability of FTO from both expression systems to form homodimers. The MST-determined dissociation constant of the FTO homodimer was consistent with their in vivo formation in human cells. Finally, a low-resolution structure of the FTO homodimer was built based on SAXS data.

scholarly journals Human Plasma and Recombinant Hemopexins: Heme Binding Revisited

2021 ◽  
Vol 22 (3) ◽  
pp. 1199
Author(s):  
Elena Karnaukhova ◽  
Catherine Owczarek ◽  
Peter Schmidt ◽  
Dominik J. Schaer ◽  
Paul W. Buehler
Keyword(s):  
Protein S ◽  
Soret Band ◽  
Cell System ◽  
Size Exclusion ◽  
Heme Binding ◽  
Systematic Analysis ◽  
Molar Ratios ◽  
Recombinant Production ◽  
Wide Range ◽  
Exclusion Chromatography

Plasma hemopexin (HPX) is the key antioxidant protein of the endogenous clearance pathway that limits the deleterious effects of heme released from hemoglobin and myoglobin (the term “heme” is used in this article to denote both the ferrous and ferric forms). During intra-vascular hemolysis, heme partitioning to protein and lipid increases as the plasma concentration of HPX declines. Therefore, the development of HPX as a replacement therapy during high heme stress could be a relevant intervention for hemolytic disorders. A logical approach to enhance HPX yield involves recombinant production strategies from human cell lines. The present study focuses on a biophysical assessment of heme binding to recombinant human HPX (rhHPX) produced in the Expi293FTM (HEK293) cell system. In this report, we examine rhHPX in comparison with plasma HPX using a systematic analysis of protein structural and functional characteristics related to heme binding. Analysis of rhHPX by UV/Vis absorption spectroscopy, circular dichroism (CD), size-exclusion chromatography (SEC)-HPLC, and catalase-like activity demonstrated a similarity to HPX fractionated from plasma. In particular, the titration of HPX apo-protein(s) with heme was performed for the first time using a wide range of heme concentrations to model HPX–heme interactions to approximate physiological conditions (from extremely low to more than two-fold heme molar excess over the protein). The CD titration data showed an induced bisignate CD Soret band pattern typical for plasma and rhHPX versions at low heme-to-protein molar ratios and demonstrated that further titration is dependent on the amount of protein-bound heme to the extent that the arising opposite CD couplet results in a complete inversion of the observed CD pattern. The data generated in this study suggest more than one binding site in both plasma and rhHPX. Furthermore, our study provides a useful analytical platform for the detailed characterization of HPX–heme interactions and potentially novel HPX fusion constructs.

scholarly journals Effect of DMPA and Molecular Weight of Polyethylene Glycol on Water-Soluble Polyurethane

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1915 ◽  
Author(s):  
Eyob Wondu ◽  
Hyun Woo Oh ◽  
Jooheon Kim
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Polyethylene Glycol ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Soft Segment ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

In this study water-soluble polyurethane (WSPU) was synthesized from isophorone diisocyanate (IPDI), and polyethylene glycol (PEG), 2-bis(hydroxymethyl) propionic acid or dimethylolpropionic acid (DMPA), butane-1,4-diol (BD), and triethylamine (TEA) using an acetone process. The water solubility was investigated by solubilizing the polymer in water and measuring the contact angle and the results indicated that water solubility and contact angle tendency were increased as the molecular weight of the soft segment decreased, the amount of emulsifier was increased, and soft segment to hard segment ratio was lower. The contact angle of samples without emulsifier was greater than 87°, while that of with emulsifier was less than 67°, indicating a shift from highly hydrophobic to hydrophilic. The WSPU was also analyzed using Fourier transform infrared spectroscopy (FT-IR) to identify the absorption of functional groups and further checked by X-ray photoelectron spectroscopy (XPS). The molecular weight of WSPU was measured using size-exclusion chromatography (SEC). The structure of the WSPU was confirmed by nuclear magnetic resonance spectroscopy (NMR). The thermal properties of WSPU were analyzed using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).

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.

A study on the kinetics and thermal properties of polystyrene/diatomite nanocomposites prepared via in situ ATRP

2018 ◽  
Vol 33 (2) ◽  
pp. 180-197 ◽  
Author(s):  
Khezrollah Khezri ◽  
Yousef Fazli
Keyword(s):  
Molecular Weight ◽  
In Situ Polymerization ◽  
Structural Characteristics ◽  
Nitrogen Adsorption ◽  
Linear Increase ◽  
Size Exclusion ◽  
Scanning Calorimetry ◽  
Morphological Studies ◽  
Exclusion Chromatography

Pristine mesoporous diatomite was employed to prepare polystyrene/diatomite composites. Diatomite platelets were used for in situ polymerization of styrene by atom transfer radical polymerization to synthesize tailor-made polystyrene nanocomposites. X-Ray fluorescence spectrometer analysis and thermogravimetric analysis (TGA) were employed for evaluating some inherent properties of pristine diatomite platelets. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the diatomite platelets. Evaluation of pore size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Linear increase of ln ( M0/M) with time for all the samples shows that polymerization proceeds in a living manner. Addition of 3 wt% pristine mesoporous diatomite leads to an increase of conversion from 72% to 89%. Molecular weight of polystyrene chains increases from 11,326 g mol−1 to 14134 g mol−1 with the addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increases from 1.13 to 1.38. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 81.9°C to 87.1°C by adding 3 wt% of mesoporous diatomite platelets.

scholarly journals Synthesis and Self-Assembly of Poly(N-Vinylcaprolactam)-b-Poly(ε-Caprolactone) Block Copolymers via the Combination of RAFT/MADIX and Ring-Opening Polymerizations

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1252
Author(s):  
Rodolfo M. Moraes ◽  
Layde T. Carvalho ◽  
Gizelda M. Alves ◽  
Simone F. Medeiros ◽  
Elodie Bourgeat-Lami ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Ring Opening ◽  
Chain Transfer ◽  
Fluorescence Probe ◽  
Size Exclusion ◽  
Proton Nuclear Magnetic Resonance ◽  
Solution Temperature ◽  
Copolymer Composition ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

Well-defined amphiphilic, biocompatible and partially biodegradable, thermo-responsive poly(N-vinylcaprolactam)-b-poly(ε-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerizations (ROP). Poly(N-vinylcaprolactam) containing xanthate and hydroxyl end groups (X–PNVCL–OH) was first synthesized by RAFT/macromolecular design by the interchange of xanthates (RAFT/MADIX) polymerization of NVCL mediated by a chain transfer agent containing a hydroxyl function. The xanthate-end group was then removed from PNVCL by a radical-induced process. Finally, the hydroxyl end-capped PNVCL homopolymer was used as a macroinitiator in the ROP of ε-caprolactone (ε-CL) to obtain PNVCL-b-PCL block copolymers. These (co)polymers were characterized by Size Exclusion Chromatography (SEC), Fourier-Transform Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), UV–vis and Differential Scanning Calorimetry (DSC) measurements. The critical micelle concentration (CMC) of the block copolymers in aqueous solution measured by the fluorescence probe technique decreased with increasing the length of the hydrophobic block. However, dynamic light scattering (DLS) demonstrated that the size of the micelles increased with increasing the proportion of hydrophobic segments. The morphology observed by cryo-TEM demonstrated that the micelles have a pointed-oval-shape. UV–vis and DLS analyses showed that these block copolymers have a temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by varying the block copolymer composition.

Differentiation of wastewater effluent organic matter (EfOM) from natural organic matter (NOM) using multiple analytical techniques

2008 ◽  
Vol 57 (7) ◽  
pp. 1009-1015 ◽  
Author(s):  
Seong-Nam Nam ◽  
Gary Amy
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Analytical Techniques ◽  
Size Exclusion ◽  
Effluent Organic Matter ◽  
Fluorescence Excitation ◽  
Wide Range ◽  
Exclusion Chromatography

Using three analytical techniques of size exclusion chromatography (SEC), fluorescence excitation-emission matrix (EEM), and dissolved organic nitrogen (DON) measurement, differentiating characteristics of effluent organic matter (EfOM) from natural organic matter (NOM) have been investigated. SEC reveals a wide range of molecular weight (MW) for EfOM and high amount of high MW polysaccharides, and low MW organic acids compared to NOM. Clear protein-like peaks using fluorescence EEM were a major feature of EfOM distinguishing it from NOM. Fluorescence index (FI), an indicator to distinguish autochthonous origin from allochthonous origin, differentiated EfOM from NOM by exhibiting higher values, indicating a microbial origin. In EfOM samples, DON present in higher amounts than NOM.

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