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https://www.readbyqxmd.com/read/28315762/bionanocomposite-films-based-on-polysaccharides-from-banana-peels
#1
Túlio Ítalo S Oliveira, Morsyleide F Rosa, Michael J Ridout, Kathryn Cross, Edy S Brito, Lorena M A Silva, Selma E Mazzetto, Keith W Waldron, Henriette M C Azeredo
Pectin and cellulose nanocrystals (CNCs) isolated from banana peels were used to prepare films. The effects of a reinforcing phase (CNCs) and a crosslinker (citric acid, CA) on properties of pectin films were studied. Glycerol-plasticized films were prepared by casting, with different CNC contents (0-10wt%), with or without CA. Overall tensile properties were improved by intermediate CNC contents (around 5wt%). The water resistance and water vapor barrier properties were also enhanced by CNC. Evidences were found from Fourier Transform Infrared (FTIR) spectra supporting the occurrence of crosslinking by CA...
March 15, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28277547/backbone-assignment-of-perdeuterated-proteins-by-solid-state-nmr-using-proton-detection-and-ultrafast-magic-angle-spinning
#2
Pascal Fricke, Veniamin Chevelkov, Maximilian Zinke, Karin Giller, Stefan Becker, Adam Lange
Solid-state NMR (ssNMR) is a technique that allows the study of protein structure and dynamics at atomic detail. In contrast to X-ray crystallography and cryo-electron microscopy, proteins can be studied under physiological conditions-for example, in a lipid bilayer and at room temperature (0-35 °C). However, ssNMR requires considerable amounts (milligram quantities) of isotopically labeled samples. In recent years, (1)H-detection of perdeuterated protein samples has been proposed as a method of alleviating the sensitivity issue...
April 2017: Nature Protocols
https://www.readbyqxmd.com/read/28274845/exploring-the-interactions-of-irbesartan-and-irbesartan-2-hydroxypropyl-%C3%AE-cyclodextrin-complex-with-model-membranes
#3
Αdamantia S Liossi, Dimitrios Ntountaniotis, Tahsin F Kellici, Maria V Chatziathanasiadou, Grigorios Megariotis, Maria Mania, Johanna Becker-Baldus, Manfred Kriechbaum, Andraž Krajnc, Eirini Christodoulou, Clemens Glaubitz, Michael Rappolt, Heinz Amenitsch, Gregor Mali, Doros N Theodorou, Georgia Valsami, Marinos Pitsikalis, Hermis Iatrou, Andreas G Tzakos, Thomas Mavromoustakos
The interactions of irbesartan (IRB) and irbesartan-2-hydroxypropyl-β-cyclodextrin (HP-β-CD) complex with dipalmitoyl phosphatidylcholine (DPPC) bilayers have been explored utilizing an array of biophysical techniques ranging from differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), ESI mass spectrometry (ESI-MS) and solid state nuclear magnetic resonance (ssNMR). Molecular dynamics (MD) calculations have been also conducted to complement the experimental results. Irbesartan was found to be embedded in the lipid membrane core and to affect the phase transition properties of the DPPC bilayers...
March 6, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28267155/atomic-scale-structure-of-amorphous-aluminum-oxyhydroxide-oxide-and-oxycarbide-films-probed-by-very-high-field-27-al-nuclear-magnetic-resonance
#4
L Baggetto, V Sarou-Kanian, P Florian, A N Gleizes, D Massiot, C Vahlas
The atomic scale structure of aluminum in amorphous alumina films processed by direct liquid injection chemical vapor deposition from aluminum tri-isopropoxide (ATI) and dimethyl isopropoxide (DMAI) is investigated by solid-state (27)Al nuclear magnetic resonance (SSNMR) using a very high magnetic field of 20.0 T. This study is performed as a function of the deposition temperature in the range 300-560 °C, 150-450 °C, and 500-700 °C, for the films processed from ATI, DMAI (+H2O), and DMAI (+O2), respectively...
March 7, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28257016/solid-state-nmr-meets-electron-diffraction-determination-of-crystalline-polymorphs-of-small-organic-microcrystalline-samples
#5
Tetsuo Oikawa, Manabu Okumura, Tsunehisa Kimura, Yusuke Nishiyama
A combination of solid-state NMR (ssNMR) and electron diffraction (ED) has been used to determine the crystalline polymorphs in small-organic microcrystalline molecules. Although (13)C cross-polarization magic angle spinning (CPMAS) is a widely used method for determining crystalline polymorphs, even in a mixture, it sometimes fails if the molecular conformations are similar. On the other hand, ED can, in principle, differentiate crystalline forms with different lattice parameters, even when they have very similar molecular conformations...
March 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
https://www.readbyqxmd.com/read/28257009/-13-c-and-19-f-solid-state-nmr-and-x-ray-crystallographic-study-of-halogen-bonded-frameworks-featuring-nitrogen-containing-heterocycles
#6
Patrick M J Szell, Shaina A Gabriel, Russell D D Gill, Shirley Y H Wan, Bulat Gabidullin, David L Bryce
Halogen bonding is a noncovalent interaction between the electrophilic region of a halogen (σ-hole) and an electron donor. We report a crystallographic and structural analysis of halogen-bonded compounds by applying a combined X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) approach. Single-crystal XRD was first used to characterize the halogen-bonded cocrystals formed between two fluorinated halogen-bond donors (1,4-diiodotetrafluorobenzene and 1,3,5-trifluoro-2,4,6-triiodobenzene) and several nitrogen-containing heterocycles (acridine, 1,10-phenanthroline, 2,3,5,6-tetramethylpyrazine, and hexamethylenetetramine)...
March 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
https://www.readbyqxmd.com/read/28254276/effect-of-carbonate-substitution-on-physicochemical-and-biological-properties-of-silver-containing-hydroxyapatites
#7
Joanna Kolmas, Urszula Piotrowska, Marzena Kuras, Eliza Kurek
Ag(+)-substituted hydroxyapatites (Ag-HAs) and Ag(+)/CO3(2-)-co-substituted hydroxyapatites (Ag-CHAs) with two different concentrations of silver ions were synthesized by the standard precipitation method. For comparison, pure hydroxyapatite (HA) and carbonated hydroxyapatite (CHA) were synthesized using the same method. The obtained powders were examined by various physicochemical methods, such PXRD, TEM, FTIR and ssNMR. Elemental analysis was provided by WD-XRF and ICP-MS methods. The strains of Staphylococcus aureus and Escherichia coli were used to evaluate the antibacterial activity of the materials...
May 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28240335/dnp-enhanced-ultrawideline-207-pb-solid-state-nmr-spectroscopy-an-application-to-cultural-heritage-science
#8
Takeshi Kobayashi, Frédéric A Perras, Anna Murphy, Yao Yao, Jaclyn Catalano, Silvia A Centeno, Cecil Dybowski, Nicholas Zumbulyadis, Marek Pruski
Dynamic nuclear polarization (DNP) is used to enhance the (ultra)wideline (207)Pb solid-state NMR spectra of lead compounds of relevance in the preservation of cultural heritage objects. The DNP SSNMR experiments enabled, for the first time, the detection of the basic lead carbonate phase of the lead white pigment by (207)Pb SSNMR spectroscopy. Variable-temperature experiments revealed that the short T'2 relaxation time of the basic lead carbonate phase hinders the acquisition of the NMR signal at room temperature...
March 14, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28219822/ultrafast-acquisition-of-1-h-1-h-dipolar-correlation-experiments-in-spinning-elastomers
#9
Laetitia Rouger, Maxime Yon, Vincent Sarou-Kanian, Franck Fayon, Jean-Nicolas Dumez, Patrick Giraudeau
We show that two widely used 2D solid-state NMR (ssNMR) pulse sequences can be implemented in an ultrafast (UF) manner, and yield 2D spectra of elastomers in a single scan, under magic-angle spinning. UF 2D ssNMR provides an acceleration of one to several orders of magnitude for classic experiments.
February 9, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28217261/affinity-of-rimantadine-enantiomers-against-influenza-a-m2-protein-revisited
#10
Antonios Drakopoulos, Christina Tzitzoglaki, Chulong Ma, Kathrin Freudenberger, Anja Hoffmann, Yanmei Hu, Günter Gauglitz, Michaela Schmidtke, Jun Wang, Antonios Kolocouris
Recent findings from solid state NMR (ssNMR) studies suggested that the (R)-enantiomer of rimantadine binds to the full M2 protein with higher affinity than the (S)-enantiomer. Intrigued by these findings, we applied functional assays, such as antiviral assay and electrophysiology (EP), to evaluate the binding affinity of rimantadine enantiomers to the M2 protein channel. Unexpectedly, no significant difference was found between the two enantiomers. Our experimental data based on the full M2 protein function were further supported by alchemical free energy calculations and isothermal titration calorimetry (ITC) allowing an evaluation of the binding affinity of rimantadine enantiomers to the M2TM pore...
February 9, 2017: ACS Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28214103/tracking-the-evolution-and-differences-between-guest-induced-phases-of-ga-mil-53-via-ultra-wideline-69-71-ga-solid-state-nmr-spectroscopy
#11
Yue Zhang, Bryan E G Lucier, Victor V Terskikh, Renlong Zheng, Yining Huang
Ga-MIL-53 is a metal-organic framework (MOF) that exhibits a "breathing effect," in which the pore size and overall MOF topology can be influenced by temperature, pressure, and host-guest interactions. The phase control afforded by this flexible framework renders Ga-MIL-53 a promising material for guest storage and sensing applications. In this work, the structure and behavior of four Ga-MIL-53 phases (as, ht, enp and lt), along with CO2 adsorbed within Ga-MIL-53 at various loading levels, has been investigated using (69/71)Ga solid-state NMR (SSNMR) experiments at 21...
January 31, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28195488/surface-sensitive-nmr-detection-of-the-solid-electrolyte-interphase-layer-on-reduced-graphene-oxide
#12
Michal Leskes, Gunwoo Kim, Tao Liu, Alison L Michan, Fabien Aussenac, Patrick Dorffer, Subhradip Paul, Clare P Grey
Forming a stable solid electrolyte interphase (SEI) is critical for rechargeable batteries' performance and lifetime. Understanding its formation requires analytical techniques that provide molecular-level insight. Here, dynamic nuclear polarization (DNP) is utilized for the first time to enhance the sensitivity of solid-state NMR (ssNMR) spectroscopy to the SEI. The approach is demonstrated on reduced graphene oxide (rGO) cycled in Li-ion cells in natural abundance and (13)C-enriched electrolyte solvents. Our results indicate that DNP enhances the signal of outer SEI layers, enabling detection of natural abundance (13)C spectra from this component of the SEI on reasonable time frames...
February 21, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28191584/sizable-dynamics-in-small-pores-co2-location-and-motion-in-the-%C3%AE-mg-formate-metal-organic-framework
#13
Yuanjun Lu, Bryan E G Lucier, Yue Zhang, Pengju Ren, Anmin Zheng, Yining Huang
Metal-organic frameworks (MOFs) are promising materials for carbon dioxide (CO2) adsorption and storage; however, many details regarding CO2 dynamics and specific adsorption site locations within MOFs remain unknown, restricting the practical uses of MOFs for CO2 capture. The intriguing α-magnesium formate (α-Mg3(HCOO)6) MOF can adsorb CO2 and features a small pore size. Using an intertwined approach of (13)C solid-state NMR (SSNMR) spectroscopy, (1)H-(13)C cross-polarization SSNMR, and computational molecular dynamics (MD) simulations, new physical insights and a rich variety of information have been uncovered regarding CO2 adsorption in this MOF, including the surprising suggestion that CO2 motion is restricted at elevated temperatures...
February 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28166408/characterization-of-the-particle-size-and-polydispersity-of-dicumarol-using-solid-state-nmr-spectroscopy
#14
Kassibla Elodie Dempah, Joseph W Lubach, Eric J Munson
A variety of particle sizes of a model compound, dicumarol, were prepared and characterized in order to investigate the correlation between particle size and solid-state NMR (SSNMR) proton spin-lattice relaxation ((1)H T1) times. Conventional laser diffraction and scanning electron microscopy were used as particle size measurement techniques and showed crystalline dicumarol samples with sizes ranging from tens of micrometers to a few micrometers. Dicumarol samples were prepared using both bottom-up and top-down particle size control approaches, via antisolvent microprecipitation and cryogrinding...
February 15, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28157561/indirect-detection-of-infinite-speed-mas-solid-state-nmr-spectra
#15
Frédéric A Perras, Amrit Venkatesh, Michael P Hanrahan, Tian Wei Goh, Wenyu Huang, Aaron J Rossini, Marek Pruski
Heavy spin-1/2 nuclides are known to possess very large chemical shift anisotropies that can challenge even the most advanced magic-angle-spinning (MAS) techniques. Wide manifolds of overlapping spinning sidebands and insufficient excitation bandwidths often obfuscate meaningful spectral information and force the use of static, low-resolution solid-state (SS)NMR methods for the characterization of materials. To address these issues, we have merged fast-magic-angle-turning (MAT) and dipolar heteronuclear multiple-quantum coherence (D-HMQC) experiments to obtain D-HMQC-MAT pulse sequences which enable the rapid acquisition of 2D SSNMR spectra that correlate isotropic (1)H chemical shifts to the indirectly detected isotropic "infinite-MAS" spectra of heavy spin-1/2 nuclides...
January 18, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28130009/practical-considerations-for-the-acquisition-of-ultra-wideline-14-n-nmr-spectra
#16
Stanislav L Veinberg, Austin W Lindquist, Michael J Jaroszewicz, Robert W Schurko
Several considerations for the acquisition, processing, and analysis of high quality ultra-wideline (UW) (14)N solid-state NMR (SSNMR) powder patterns under static conditions are discussed. It is shown that the (14)N quadrupolar parameters may be determined accurately using the frequencies of only two discontinuities in (14)N NMR powder patterns that are dominated by the first-order quadrupolar interaction, thereby eliminating the need for the acquisition of the entire pattern and concomitantly reducing experimental time...
December 21, 2016: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28094949/how-high-concentrations-of-proteins-stabilize-the-amorphous-state-of-calcium-orthophosphate-a-solid-state-nuclear-magnetic-resonance-nmr-study-of-the-casein-case
#17
Paulo De Sa Peixoto, Juliana V C Silva, Guillaume Laurent, Marc Schmutz, Daniel Thomas, Antoine Bouchoux, Geneviève Gésan-Guiziou
Understanding how proteins stabilize amorphous calcium ortho-phosphate (ACP) phases is of great importance in biology and for pharmaceutical or food applications. Until now, most of the former investigations about ACP-protein stability and equilibrium were performed under conditions where ACP colloidal nanoclusters are surrounded by low to moderate concentrations of peptides or proteins (15-30 g L(-1)). As a result, the question of ACP-protein interactions in highly concentrated protein systems has clearly been overlooked, whereas it corresponds to actual industrial conditions such as drying or membrane filtration in the dairy industry for instance...
January 30, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28094514/structural-model-of-the-tubular-assembly-of-the-rous-sarcoma-virus-capsid-protein
#18
Jaekyun Jeon, Xin Qiao, Ivan Hung, Alok K Mitra, Ambroise Desfosses, Daniel Huang, Peter L Gor'kov, Rebecca C Craven, Richard L Kingston, Zhehong Gan, Fangqiang Zhu, Bo Chen
The orthoretroviral capsid protein (CA) assembles into polymorphic capsids, whose architecture, assembly, and stability are still being investigated. The N-terminal and C-terminal domains of CA (NTD and CTD, respectively) engage in both homotypic and heterotypic interactions to create the capsid. Hexameric turrets formed by the NTD decorate the majority of the capsid surface. We report nearly complete solid-state NMR (ssNMR) resonance assignments of Rous sarcoma virus (RSV) CA, assembled into hexamer tubes that mimic the authentic capsid...
January 27, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28068097/characterization-of-phase-separation-propensity-for-amorphous-spray-dried-dispersions
#19
Daniel McNamara, Shawn Yin, Duohai Pan, George Crull, Peter Timmins, Balvinder Vig
A generalized screening approach, applying isothermal calorimetry at 37 °C 100% RH, to formulations of spray dried dispersions (SDDs) for two active pharmaceutical ingredients (APIs) (BMS-903452 and BMS-986034) is demonstrated. APIs 452 and 034, with similar chemotypes, were synthesized and promoted during development for oral dosing. Both APIs were formulated as SDDs for animal exposure studies using the polymer hydroxypropylmethlycellulose acetyl succinate M grade (HPMCAS-M). 452 formulated at 30% (wt/wt %) was an extremely robust SDD that was able to withstand 40 °C 75% RH open storage conditions for 6 months with no physical evidence of crystallization or loss of dissolution performance...
January 20, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28063904/a-rational-approach-towards-development-of-amorphous-solid-dispersions-experimental-and-computational-techniques
#20
Paroma Chakravarty, Joseph W Lubach, Jonathan Hau, Karthik Nagapudi
The purpose of this study was to determine the drug-polymer miscibility of GENE-A, a Genentech molecule, and hydroxypropyl methylcellulose-acetate succinate (HPMC-AS), a polymer, using computational and experimental approaches. The Flory-Huggins interaction parameter,χ, was obtained by calculating the solubility parameters for GENE-A and HPMC-AS over the temperature range of 25-100°C to obtain the free energy of mixing at different drug loadings (0-100%) using the Materials Studio modeling and simulation platform (thermodynamic approach)...
March 15, 2017: International Journal of Pharmaceutics
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