scholarly journals Hyaluronic Acid Functionalization with Jeffamine® M2005: A Comparison of the Thermo-Responsiveness Properties of the Hydrogel Obtained through Two Different Synthesis Routes

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 88
Author(s):  
Mathieu Madau ◽  
Didier Le Le Cerf ◽  
Virginie Dulong ◽  
Luc Picton
Keyword(s):  
Hyaluronic Acid ◽  
Aprotic Solvent ◽  
Rheological Behaviour ◽  
Gel Strength ◽  
Coupling Reagents ◽  
Coupling Reagent ◽  
Polar Aprotic Solvent ◽  
Poorly Soluble ◽  
Synthesis Routes ◽  
Responsive Hydrogels

Hyaluronic acid (HA) of different molar masses (respectively 38,000, 140,000 and 1,200,000 g.mol−1) have been functionalized with a commercial poly(etheramine), Jeffamine® M2005, in order to devise physical thermo-responsive hydrogels. Two routes have been studied, involving the use of either water for the first one or of N,N’-Dimethylformamide (DMF), a polar aprotic solvent, for the second one. In the case of the water route, the reaction was performed using a mixture of N-(3-Dimethylaminopropyl)-N’-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) as coupling reagents. The reaction was optimized while making sure no free M2005 remained in the final material, leading to M2005 grafting degrees of about 4%, which enabled the formation of hydrogels by increasing the temperature. In the case of the organic solvent route, propylphosphonic anhydride T3P® was used as a coupling reagent in DMF, resulting in a M2005 grafting degree of around 8% with better thermo-responsive properties of HA-g-M2005 compared to those obtained when the reaction was performed in water. However, the reaction systematically led to covalent cross-linking in the case of the HA, with the highest starting molar masses resulting in a very different rheological behaviour and with higher gel strength retaining thermo-responsive behaviour but being only poorly soluble in water.

scholarly journals ENHANCEMENT OF THE SOLUBILITY OF FAMOTIDINE SOLID DISPERSION USING NATURAL POLYMER BY SOLVENT EVAPORATION

2021 ◽  
pp. 193-198
Author(s):  
HUSSEIN K. ALKUFI ◽  
ASMAA M. RASHID
Keyword(s):  
Hyaluronic Acid ◽  
Solid Dispersion ◽  
Solid Dispersions ◽  
Solvent Evaporation ◽  
Water Soluble ◽  
Poorly Soluble Drugs ◽  
Natural Polymer ◽  
Solubility Study ◽  
Poorly Soluble ◽  
Pure Drug

Objective: The aims of the study to enhance solubility and dissolution of famotidine using natural polymer. Solubility study of a drug is one of the contributing factors of its oral bioavailability. The formulation of poorly soluble drugs for oral delivery presents a challenge to the formulation technologists. Methods: The present study has shown that it is possible to raise the solubility for poorly soluble drugs like famotidine, by preparing solid dispersion using natural water-soluble polymer (xyloglucan and hyaluronic acid) as solubilizer through solvent evaporation method. Physical mixture and solid dispersion of famotidine with xyloglucan (XG) or hyaluronic acid in a ratio of 1:1, 1:2, 1:3 were prepared. Solubility study, drug content, dissolution profile and compatibility study were performed for famotidine in solid dispersions XS1, XS2, XS3, HS4, HS5, HS6 as well as in physical mixtures at a ratio 1:1 for both polymer (XG and hyaluronic acid). Results: It was observed that solid dispersions of each drugs showed an increase in dissolution rate in comparison with its pure drug in the ratio of 1:1 (Drug: carrier). It can be concluded that with the care and proper use of xyloglucan, the solubility of drugs poorly soluble can be improved. The prepared solid dispersion showed improvement of drug solubility in all prepared formulas. The best result was obtained with formula XS1 (famotidine: xyloglucan at ratio 1:1) that showed 26 fold increase in solubility compared to the solubility of pure drug. Conclusion: The natural solid dispersion, increased wettability and reduced crystallinity of the drug which leads to improving solubility and dissolution.

Cyclic trimers of phosphinic acids in polar aprotic solvent: symmetry, chirality and H/D isotope effects on NMR chemical shifts

2018 ◽  
Vol 20 (7) ◽  
pp. 4901-4910 ◽  
Author(s):  
V. V. Mulloyarova ◽  
I. S. Giba ◽  
M. A. Kostin ◽  
G. S. Denisov ◽  
I. G. Shenderovich ◽  
...  
Keyword(s):  
Aprotic Solvent ◽  
Chemical Shifts ◽  
Isotope Effects ◽  
Nmr Chemical Shifts ◽  
Polar Aprotic Solvent ◽  
Phosphinic Acids ◽  
Proton Chemical Shifts ◽  
Bonded Complexes ◽  
Hydrogen Bonded

By using NMR in liquefied gases, the stoichiometry of hydrogen-bonded complexes is determined via H/D isotope effects on proton chemical shifts.

Solvolysis of sulphonyl halides. VIII. Reaction of methane and ethane sulphony1 chlorides with methanol, ethanol, and mixed solvent systems

1971 ◽  
Vol 24 (4) ◽  
pp. 713 ◽  
Author(s):  
R Foon ◽  
AN Hambly
Keyword(s):  
Carbon Tetrachloride ◽  
Room Temperature ◽  
Reaction Rate ◽  
Mixed Solvent ◽  
Aprotic Solvent ◽  
Excess Enthalpies ◽  
Initial State ◽  
Polar Aprotic Solvent ◽  
Rate Of Reaction ◽  
Solvent Systems

At room temperature methanesulphonyl chloride reacts more rapidly than ethanesulphonyl chloride in solvolysis by ethanol. Their rates of reaction with methanol are approximately equal while ethanesulphonyl chloride is the more reactive in hydrolysis. The enthalpies and entropies of activation have been determined for the solvolysis of ethanesulphonyl chloride in mixtures of ethanol with benzene, carbon tetrachloride, or 2,2,4-trimethylpentane. A comparison of the excess enthalpies and entropies of mixing in the formation of these solvents with the corresponding parameters for reaction shows that the effects on reaction rate are not due merely to the modification of the initial state of the system. The effect of the polar aprotic solvent nitrobenzene on the rate of reaction with methanol is attributed to an increase in the nucleophilic tendency of the methanol rather than to solvation of the reactive centre in the transition state.

Poly(vinylpyrrolidone) Coated Iron Nanoparticles in Polar Aprotic Solvent

2008 ◽  
Vol 8 (4) ◽  
pp. 2091-2095 ◽  
Author(s):  
Zhihui Ban ◽  
Brian L. Cushing ◽  
Charles J. O'Connor
Keyword(s):  
Iron Nanoparticles ◽  
Aprotic Solvent ◽  
Shell Structures ◽  
Iron Core ◽  
Capping Agent ◽  
Squid Magnetometry ◽  
X Ray ◽  
Transmission Electron ◽  
Polar Aprotic Solvent ◽  
Core Nanoparticles

Poly(vinylpyrrolidone) (PVP) coated iron nanoparticles which show well-defined core–shell structures have been successfully synthesized in a polar aprotic solvent. In this approach, PVP was employed not as capping agent, but as coating polymer directly applied to the metallic (iron) core nanoparticles. The morphologies, structures, compositions and magnetic properties of the products were investigated by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS), SQUID magnetometry and FTIR spectroscopy.

Ynamide: A New Coupling Reagent for Amide and Peptide Synthesis

Synlett ◽  
2017 ◽  
Vol 28 (14) ◽  
pp. 1663-1670 ◽  
Author(s):  
Long Hu ◽  
Junfeng Zhao
Keyword(s):  
Peptide Synthesis ◽  
Phosphonium Salt ◽  
Peptide Fragment ◽  
Coupling Reagents ◽  
Development History ◽  
Coupling Reagent ◽  
History Of ◽  
Fragment Condensation ◽  
Carbodiimide Coupling ◽  
Guanidinium Salt

The discovery and application of ynamide coupling reagents is highlighted with a brief summary of the development history of coupling reagents in amide and peptide synthesis. As novel coupling reagents, ynamides are not only effective for simple amide and dipeptide synthesis but also can be used for peptide fragment condensation. More importantly, no racemization was detected during the activation of α-chiral carboxylic acids by employing ynamide coupling reagents.1 Introduction2 Carbodiimide Coupling Reagents3 Uronium/Guanidinium Salt Coupling Reagents4 Phosphonium Salt Coupling Reagents5 Ethoxyacetylene as a Coupling Reagent6 Ynamine Coupling Reagents7 Ynamide Coupling Reagents8 Summary and Outlook

scholarly journals Hyaluronic Acid Based Hydrogels for Regenerative Medicine Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Assunta Borzacchiello ◽  
Luisa Russo ◽  
Birgitte M. Malle ◽  
Khadija Schwach-Abdellaoui ◽  
Luigi Ambrosio
Keyword(s):  
Hyaluronic Acid ◽  
Viscoelastic Properties ◽  
Structural Parameters ◽  
Weight Ratio ◽  
Rheological Behaviour ◽  
Biological Properties ◽  
Cross Linking ◽  
In Vitro Tests ◽  
The Cross

Hyaluronic acid (HA) hydrogels, obtained by cross-linking HA molecules with divinyl sulfone (DVS) based on a simple, reproducible, and safe process that does not employ any organic solvents, were developed. Owing to an innovative preparation method the resulting homogeneous hydrogels do not contain any detectable residual cross-linking agent and are easier to inject through a fine needle. HA hydrogels were characterized in terms of degradation and biological properties, viscoelasticity, injectability, and network structural parameters. They exhibit a rheological behaviour typical of strong gels and show improved viscoelastic properties by increasing HA concentration and decreasing HA/DVS weight ratio. Furthermore, it was demonstrated that processes such as sterilization and extrusion through clinical needles do not imply significant alteration of viscoelastic properties. Both SANS and rheological tests indicated that the cross-links appear to compact the network, resulting in a reduction of the mesh size by increasing the cross-linker amount. In vitro degradation tests of the HA hydrogels demonstrated that these new hydrogels show a good stability against enzymatic degradation, which increases by increasing HA concentration and decreasing HA/DVS weight ratio. Finally, the hydrogels show a good biocompatibility confirmed by in vitro tests.

CULTIVATION OF CHONDROCYTES AND MENISCUS CELLS IN THERMO-RESPONSIVE HYDROGELS CONTAINING CHITOSAN AND HYALURONIC ACID UNDER MECHANICAL TENSILE STIMULATION

2011 ◽  
Vol 11 (05) ◽  
pp. 1003-1015 ◽  
Author(s):  
JYH-PING CHEN ◽  
HAN-TSUNG LIAO ◽  
TAI-HONG CHENG
Keyword(s):  
Cell Proliferation ◽  
Hyaluronic Acid ◽  
Tensile Strain ◽  
Biosynthetic Activity ◽  
Hydrogel Scaffold ◽  
Primary Chondrocytes ◽  
Temperature Responsive ◽  
Mechanical Tensile ◽  
Meniscus Cells ◽  
Responsive Hydrogels

Temperature-responsive hydrogel scaffold containing chitosan and hyaluronic acid was used to entrap primary chondrocytes and meniscus cells. The effect of dynamic tensile strain on the cells/hydrogel constructs was evaluated by measuring cell proliferation, biosynthetic activity, and viability. The results demonstrated that mechanical deformation applied at 15% tensile strain, 0.5 Hz, and 10 min per day for 43 days resulted in substantial increases in glycosaminoglycan (36% for chondrocytes and 31% for meniscus cells) and collagen productions (37% for chondrocytes and 52% for meniscus cells) over static controls while not significantly affecting cell proliferation and viability.

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