Properties of Therapeutic Deep Eutectic Solvents of l-Arginine and Ethambutol for Tuberculosis Treatment

The treatment for tuberculosis infection usually involves a prolonged regimen of multiple antibacterial drugs, which might lead to various secondary effects. For preventing drug resistance and side-effects of anti-tuberculosis drugs, new methods for improving the bioavailability of APIs were investigated. The strategy proposed consists of the preparation of therapeutic deep eutectic solvents (THEDES), that incorporate l-arginine and ethambutol. The eutectic mixtures were prepared by mixing the components at a certain molar ratio, until a clear liquid solution was formed. The prepared mixtures were characterized by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and nuclear magnetic resonance spectroscopy (1H and 13C-NMR). The solubility and permeability of the drugs when they are in the THEDES form was evaluated at 37 °C, in phosphate buffered saline (PBS). Solubility studies showed an increase of the solubility of ethambutol when incorporated in the eutectic system. The cytotoxicity was evaluated using a model cell line (Caco-2), comparing the cytotoxicity of the API incorporated in the eutectic system. We observed that the cell viability in the THEDES was affected by the presence of citric acid, and higher cytotoxicity values were observed. Nonetheless, these findings do not compromise the possibility to use these systems as new delivery systems for ethambutol and arginine.

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

High Temperature Materials and Processes ◽

10.1515/htmp-2015-0244 ◽

2017 ◽

Vol 36 (10) ◽

pp. 955-962 ◽

Cited By ~ 6

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.

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Synthesis of spin-labelled 2-(16′-(N-oxyl-4″,4″-dimethyloxazolidine)stearoyl)-phosphatidylcholine

Canadian Journal of Biochemistry ◽

10.1139/o80-020 ◽

1980 ◽

Vol 58 (2) ◽

pp. 143-146 ◽

Cited By ~ 6

Author(s):

D. J. Vaughan ◽

N. Z. Stanacev

Keyword(s):

Protein Interactions ◽

Egg Yolk ◽

Molar Ratio ◽

Resonance Spectroscopy ◽

Scanning Calorimetry ◽

Spin Resonance ◽

Dimyristoyl Phosphatidylcholine ◽

Label Probe ◽

Lipid Protein Interactions ◽

Good Agreement

Chemical synthesis of spin-labelled lecithin 2-(16′-(N-oxyl-4″,4″-dimethyloxazolidine)-stearoyl)-phosphatidylcholine was achieved by reaction of equimolar amounts of purified egg yolk lyso-lecithin with commercially available 16-(N-oxyl-4′,4′-dimethyloxazolidine)stearic acid activated with N,N-carbonyldiimidazole. After purification by silicic acid column chromatography, spin-labelled lecithin was obtained in 52.2% yield and had an ester:phosphorus:spin molar ratio of 2.0:1.1:1.0. When dimyristoyl-phosphatidylcholine and dimyristoyl-phosphatidylcholine:cholesterol (10:1) liposomes, containing 2-(16′-(N-oxyl-4″,4″-dimethyloxazolidine)stearoyl)-phosphatidylcholine as a probe, were examined for thermotropic changes monitored by electron spin resonance spectroscopy, transition temperatures of 24.0 and 24.2 °C, respectively, were obtained in a very good agreement with previously reported values obtained with different probes and by different techniques, and with our own differential scanning calorimetry measurements. The potential usefulness of synthetic 2-(16′-(N-oxyl-4″,4″-dimethyloxazolidine)stearoyl)-phosphatidylcholine as a spin-label probe in studies of lipid–protein interactions in biological membranes was discussed.

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Influence of the Molecular Structure of Constituents and Liquid Phase Non-Ideality on the Viscosity of Deep Eutectic Solvents

Molecules ◽

10.3390/molecules26144208 ◽

2021 ◽

Vol 26 (14) ◽

pp. 4208

Author(s):

Ahmad Alhadid ◽

Liudmila Mokrushina ◽

Mirjana Minceva

Keyword(s):

Molecular Structure ◽

Melting Temperature ◽

Deep Eutectic Solvents ◽

Liquid Solution ◽

High Viscosity ◽

Molar Ratio ◽

Natural Substances ◽

Low Viscosity ◽

Wide Range ◽

Eutectic Systems

Hydrophobic deep eutectic solvents (DES) have recently been used as green alternatives to conventional solvents in several applications. In addition to their tunable melting temperature, the viscosity of DES can be optimized by selecting the constituents and molar ratio. This study examined the viscosity of 14 eutectic systems formed by natural substances over a wide range of temperatures and compositions. The eutectic systems in this study were classified as ideal or non-ideal based on their solid–liquid equilibria (SLE) data found in the literature. The eutectic systems containing constituents with cyclohexyl rings were considerably more viscous than those containing linear or phenyl constituents. Moreover, the viscosity of non-ideal eutectic systems was higher than that of ideal eutectic systems because of the strong intermolecular interactions in the liquid solution. At temperatures considerably lower than the melting temperature of the pure constituents, non-ideal and ideal eutectic systems with cyclohexyl constituents exhibited considerably high viscosity, justifying the kinetic limitations in crystallization observed in these systems. Overall, understanding the correlation between the molecular structure of constituents, SLE, and the viscosity of the eutectic systems will help in designing new, low-viscosity DES.

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Evaluation of glass transition in model cell lines using differential scanning calorimetry

Cytotherapy ◽

10.1016/s1465324921005715 ◽

2021 ◽

Vol 23 (5) ◽

pp. S173

Author(s):

C. Jones ◽

J. Heimfeld ◽

B.J. Hawkins ◽

R. Marcu

Keyword(s):

Differential Scanning Calorimetry ◽

Glass Transition ◽

Cell Lines ◽

Scanning Calorimetry ◽

Model Cell

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Physicochemical properties and structural dynamics of organic–inorganic hybrid [NH3(CH2)3NH3]ZnX4 (X = Cl and Br) crystals

Scientific Reports ◽

10.1038/s41598-021-87940-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ae Ran Lim ◽

Sun Ha Kim ◽

Yong Lak Joo

Keyword(s):

Structural Dynamics ◽

Chemical Shifts ◽

Lattice Relaxation ◽

Magic Angle Spinning ◽

Spin Lattice Relaxation ◽

Resonance Spectroscopy ◽

Magic Angle ◽

Scanning Calorimetry ◽

Inorganic Hybrid ◽

Halogen Atoms

AbstractThe physical properties of the organic–inorganic hybrid crystals having the formula [NH3(CH2)3NH3]ZnX4 (X = Cl, Br) were investigated. The phase transition temperatures (TC; 268K for Cl and 272K for Br) of the two crystals bearing different halogen atoms in their skeletons were determined through differential scanning calorimetry. The thermodynamic properties of the two crystals were investigated through thermogravimetric analysis. The structural dynamics, particularly the role of the [NH3(CH2)3NH3] cation, were probed through 1H and 13C magic-angle spinning nuclear magnetic resonance spectroscopy as a function of temperature. The 1H and 13C NMR chemical shifts did not show any changes near TC. In addition, the 1H spin–lattice relaxation time (T1ρ) varied with temperature, whereas the 13C T1ρ values remained nearly constant at different temperatures. The T1ρ values of the atoms in [NH3(CH2)3NH3]ZnCl4 were higher than those in [NH3(CH2)3NH3]ZnBr4. The observed differences in the structural dynamics obtained from the chemical shifts and T1ρ values of the two compounds can be attributed to the differences in the bond lengths and halogen atoms. These findings can provide important insights or potential applications of these crystals.

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Synthesis and Characterization of N-Substituted Polyether-Block-Amide Copolymers

Materials ◽

10.3390/ma14040773 ◽

2021 ◽

Vol 14 (4) ◽

pp. 773

Author(s):

Jyun-Yan Ye ◽

Kuo-Fu Peng ◽

Yu-Ning Zhang ◽

Szu-Yuan Huang ◽

Mong Liang

Keyword(s):

Titanium Isopropoxide ◽

Decomposition Temperature ◽

Phenyl Isocyanate ◽

Cross Linking ◽

Resonance Spectroscopy ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Degradation Temperature ◽

Melt Polycondensation ◽

Structural Regularity

A series of N-substituted polyether-block-amide (PEBA-X%) copolymers were prepared by melt polycondensation of nylon-6 prepolymer and polytetramethylene ether glycol at an elevated temperature using titanium isopropoxide as a catalyst. The structure, thermal properties, and crystallinity of PEBA-X% were investigated using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, wide angle X-ray diffraction, and thermogravimetric analysis. In general, the crystallinity, melting point, and thermal degradation temperature of PEBA-X% decreased as the incorporation of N-methyl functionalized groups increased, owing to the disruption caused to the structural regularity of the copolymer. However, in N-acetyl functionalized analogues, the crystallinity first dropped and then increased because of a new γ form arrangement that developed in the microstructure. After the cross-linking reaction of the N-methyl-substituted derivative, which has electron-donating characteristics, with poly(4,4′-methylenebis(phenyl isocyanate), the decomposition temperature of the resulting polymer significantly increased, whereas no such improvements could be observed in the case of the electro-withdrawing N-acetyl-substituted derivative, because of the incompleteness of its cross-linking reaction.

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

Polymers ◽

10.3390/polym11121915 ◽

2019 ◽

Vol 11 (12) ◽

pp. 1915 ◽

Cited By ~ 2

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).

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Clozapine-carboxylic acid plasticized co-amorphous dispersions: Preparation, characterization and solution stability evaluation

Acta Pharmaceutica ◽

10.1515/acph-2015-0014 ◽

2015 ◽

Vol 65 (2) ◽

pp. 133-146 ◽

Cited By ~ 18

Author(s):

Ahmed Mahmoud Abdelhaleem Ali ◽

Adel Ahmed Ali ◽

Ibrahim Abdullah Maghrabi

Keyword(s):

Carboxylic Acid ◽

Tartaric Acid ◽

Molar Ratio ◽

Sublingual Administration ◽

Solution Stability ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Great Chance ◽

Amorphous Dispersions ◽

Pass Metabolism

Abstract This study addressed the possibility of forming of co-amorphous systems between clozapine (CZ) and various carboxylic acid plasticizers (CAPs). The aim was to improve the solubility and oral bioavailability of clozapine. Co-amorphous dispersions were prepared using modified solvent evaporation methodology at drug/plasticizer stoichiometric ratios of 1:1, 1:1.5 and 1:2. Solid state characterization was performed using differential scanning calorimetry, X-ray diffraction and infra red spectroscopy. Highly soluble homogeneous co-amorphous dispersions were formed between clozapine and CAPs via hydrogen bonding. The co-amorphous dispersions formed with tartaric acid (1:2) showed the highest dissolution percentage (> 95 % in 20 minutes) compared to pure crystalline CZ (56 %). Highly stable solutions were obtained from co-amorphous CZ-citric and CZ-tartaric acid at 1:1.5 molar ratio. The prepared dispersions suggest the possibility of peroral or sublingual administration of highly soluble clozapine at a reduced dose with the great chance to bypass the first pass metabolism.

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Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-13321-2016 ◽

2016 ◽

Vol 16 (20) ◽

pp. 13321-13340 ◽

Cited By ~ 54

Author(s):

Xingjun Fan ◽

Siye Wei ◽

Mengbo Zhu ◽

Jianzhong Song ◽

Ping'an Peng

Keyword(s):

Coal Combustion ◽

Fossil Fuels ◽

Solid Phase ◽

Water Soluble ◽

Total Carbon ◽

Atmospheric Environment ◽

Molar Ratio ◽

Resonance Spectroscopy ◽

Molar Ratios ◽

Biomass Materials

Abstract. Humic-like substances (HULIS) in smoke fine particulate matter (PM2.5) emitted from the combustion of biomass materials (rice straw, corn straw, and pine branch) and fossil fuels (lignite coal and diesel fuel) were comprehensively studied in this work. The HULIS fractions were first isolated with a one-step solid-phase extraction method, and were then investigated with a series of analytical techniques: elemental analysis, total organic carbon analysis, UV–vis (ultraviolet–visible) spectroscopy, excitation–emission matrix (EEM) fluorescence spectroscopy, Fourier transform infrared spectroscopy, and 1H-nuclear magnetic resonance spectroscopy. The results show that HULIS account for 11.2–23.4 and 5.3 % of PM2.5 emitted from biomass burning (BB) and coal combustion, respectively. In addition, contributions of HULIS-C to total carbon and water-soluble carbon in smoke PM2.5 emitted from BB are 8.0–21.7 and 56.9–66.1 %, respectively. The corresponding contributions in smoke PM2.5 from coal combustion are 5.2 and 45.5 %, respectively. These results suggest that BB and coal combustion are both important sources of HULIS in atmospheric aerosols. However, HULIS in diesel soot only accounted for ∼  0.8 % of the soot particles, suggesting that vehicular exhaust may not be a significant primary source of HULIS. Primary HULIS and atmospheric HULIS display many similar chemical characteristics, as indicated by the instrumental analytical characterization, while some distinct features were also apparent. A high spectral absorbance in the UV–vis spectra, a distinct band at λex∕λem ≈  280∕350 nm in EEM spectra, lower H ∕ C and O ∕ C molar ratios, and a high content of [Ar–H] were observed for primary HULIS. These results suggest that primary HULIS contain more aromatic structures, and have a lower content of aliphatic and oxygen-containing groups than atmospheric HULIS. Among the four primary sources of HULIS, HULIS from BB had the highest O ∕ C molar ratios (0.43–0.54) and [H–C–O] content (10–19 %), indicating that HULIS from this source mainly consisted of carbohydrate- and phenolic-like structures. HULIS from coal combustion had a lower O ∕ C molar ratio (0.27) and a higher content of [Ar–H] (31 %), suggesting that aromatic compounds were extremely abundant in HULIS from this source. Moreover, the absorption Ångström exponents of primary HULIS from BB and coal combustion were 6.7–8.2 and 13.6, respectively. The mass absorption efficiencies of primary HULIS from BB and coal combustion at 365 nm (MAE365) were 0.97–2.09 and 0.63 m2 gC−1, respectively. Noticeably higher MAE365 values for primary HULIS from BB than coal combustion indicate that the former has a stronger contribution to the light-absorbing properties of aerosols in the atmospheric environment.

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Synthesis, Characterization and Application of Multi-Generations Hyperbranched Polyurethane Based on Isophorone Diisocyanate

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.554-556.126 ◽

2012 ◽

Vol 554-556 ◽

pp. 126-129 ◽

Cited By ~ 3

Author(s):

Shun Yin ◽

Ning Sun ◽

Chun Yun Feng ◽

Zhi Mou Wu ◽

Zhao Hua Xu ◽

...

Keyword(s):

Differential Scanning Calorimetry ◽

Raw Materials ◽

Degradation Mechanism ◽

Resonance Spectroscopy ◽

Gravimetric Analysis ◽

Thermal Gravimetric ◽

Isophorone Diisocyanate ◽

Scanning Calorimetry ◽

Degradation Temperature ◽

Hyperbranched Polyurethane

A series of different generation hyperbranched polyurethane(HBPU) was synthesized based on the raw materials of isophorone diisocyanate(IPDI) and diethanolamine(DEOA). Their structure, thermal degradation mechanism and glass transition temperature(Tg) were characterized by fourier transform infrared spectroscopy(FTIR), nuclear magnetic resonance spectroscopy(NMR), thermal gravimetric analysis(TGA) and differential scanning calorimetry(DSC). The results showed that: the yield of each generation HBPU was up to 90%, different generation HBPU had almost the same initial degradation temperature(about at 200°C) and they all had two decomposition platforms; with the increase of generation, Tg increased from 107.2°C to 132.1°C. The gloss and hardness of the HBPU coatings were significantly improved.

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