scholarly journals Preparation and Characterization of Stealth Archaeosomes Based on a Synthetic PEGylated Archaeal Tetraether Lipid

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Julie Barbeau ◽  
Sandrine Cammas-Marion ◽  
Pierrick Auvray ◽  
Thierry Benvegnu
Keyword(s):  
High Performance ◽  
Drug Carriers ◽  
Physicochemical Characteristics ◽  
Release Studies ◽  
Poly Ethylene ◽  
Membrane Spanning ◽  
The Stability ◽  
The One ◽  
Egg Pc

The present studies were focused on the formation and characterization of sterically stabilized archaeosomes made from a synthetic PEGylated archaeal lipid. In a first step, a synthetic archaeal tetraether bipolar lipid was functionalized with a poly(ethylene glycol), PEG, and (PEG45-Tetraether) with the aim of coating the archaeosome surface with a sterically stabilizing hydrophilic polymer. In a second step, Egg-PC/PEG45-Tetraether (90/10 wt%) archaeosomes were prepared, and their physicochemical characteristics were determined by dynamic light scattering (size, polydispersity), cryo-TEM (morphology), and by high-performance thin layer chromatography (lipid composition), in comparison with standard Egg-PC/PEG45-DSPE formulations. Further, a fluorescent dye, the carboxyfluorescein, was encapsulated into the prepared archaeosomes in order to evaluate the potential of such nanostructures as drug carriers. Release studies have shown that the stability of Egg-PC/PEG45-Tetraether-based archaeosomes is significantly higher at 37∘C than the one of Egg-PC/PEG45-DSPE-based liposomes, as evidenced by the slower release of the dye encapsulated into PEGylated archaeosomes. This enhanced stability could be related to the membrane spanning properties of the archaeal bipolar lipid as already described with natural or synthetic tetraether lipids.

Physicochemical Characterization of Solid Dispersions of Cefdinir with PVP K-30 and PEG 4000

2010 ◽  
Vol 3 (2) ◽  
pp. 948-956
Author(s):  
Kumar P ◽  
S Kumar ◽  
A Kumar ◽  
M Chander
Keyword(s):  
Solid Dispersions ◽  
Physicochemical Characterization ◽  
Drug Carriers ◽  
Dissolution Properties ◽  
Rate Of Dissolution ◽  
Peg 4000 ◽  
Release Studies ◽  
Crystalline Nature ◽  
Physical Mixtures

The purpose of this study was to prepare and characterize solid dispersions of the antibacterial agent Cefdinir with PEG 4000 and PVP K-30 with a view to improve its dissolution properties. Investigations of the properties of the dispersions were performed using release studies, X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR). The results obtained showed that the rate of dissolution of Cefdinir was considerably improved when formulated in solid dispersions with PVP K-30 and PEG 4000 as compared with pure drug and physical mixtures. The results from XRD studies showed the transition of crystalline nature of drug to amorphous form, while FTIR studies demonstrated the absence of drug-carriers interaction.

scholarly journals Preparation and Characterization of Whey Protein-Based Polymers Produced from Residual Dairy Streams

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 722 ◽  
Author(s):  
Chalermthai ◽  
Chan ◽  
Bastidas-Oyanedel ◽  
Taher ◽  
Olsen ◽  
...  
Keyword(s):  
Whey Protein ◽  
Protein Concentration ◽  
Milk Proteins ◽  
Protein Isolate ◽  
Whey Protein Concentrate ◽  
Polymer Sheets ◽  
Lower Protein ◽  
Poly Ethylene ◽  
The One

The wide use of non-biodegradable, petroleum-based plastics raises important environmental concerns, which urges finding alternatives. In this study, an alternative way to produce polymers from a renewable source—milk proteins—was investigated with the aim of replacing polyethylene. Whey protein can be obtained from whey residual, which is a by-product in the cheese-making process. Two different sources of whey protein were tested: Whey protein isolate (WPI) containing 91% protein concentration and whey protein concentrate (WPC) containing 77% protein concentration. These were methacrylated, followed by free radical polymerization with co-polymer poly(ethylene glycol) methyl ether methacrylate (PEGMA) to obtain polymer sheets. Different protein concentrations in water (11–14 w/v%), at two protein/PEGMA mass-ratios, 20:80 and 30:70, were tested. The polymers made from WPI and WPC at a higher protein/PEGMA ratio of 30:70 had significantly better tensile strength than the one with lower protein content, by about 1–2 MPa (the best 30:70 sample exhibited 3.8 ± 0.2 MPa and the best 20:80 sample exhibited 1.9 ± 0.4 MPa). This indicates that the ratio between the hard (protein) and soft (copolymer PEGMA) domains induce significant changes to the tensile strengths of the polymer sheets. Thermally, the WPI-based polymer samples are stable up to 277.8 ± 6.2 °C and the WPC-based samples are stable up to 273.0 ± 3.4 °C.

scholarly journals Synthesis and Characterization of Novel Copolymeric Resveratrol Conjugates

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yan-Jing Ng ◽  
Heather A. E. Benson ◽  
David H. Brown ◽  
Yan Chen
Keyword(s):  
Micelle Formation ◽  
Rat Plasma ◽  
The Body ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene ◽  
The Stability ◽  
Chain Lengths ◽  
Cardioprotective Drug

Resveratrol (RSV), naturally found in plants, is known to have health benefits and has been proposed as a potential anticancer and cardioprotective drug. However, due to its molecular structure, it undergoes rapid metabolism in the body resulting in low bioavailability. Novel polymeric methoxy-poly(ethylene glycol)-block-poly(ε-caprolactone) (mPEG-PCL) RSV conjugates with varying PCL chain lengths have been synthesised and formulated into micelles and/or nanoparticles for preliminaryin vitrostability studies. RSV conjugated with mPEG2000-PCL9500 was found to have improved solubility and stability of RSV as compared to RSV alone. The length of the PCL chain was found to affect the micelle formation, hence the stability in physiological buffers and rat plasma.

scholarly journals Physicochemical characterization of the pulp oil of bacuri Attalea phalerata Mart. ex Spreng. (Arecaceae)

2020 ◽  
Vol 21 (3) ◽  
pp. 1-11
Author(s):  
Michelle Cardoso Coimbra ◽  
Débora Maria Moreno Luzia ◽  
Neuza Jorge
Keyword(s):  
Fatty Acids ◽  
Gas Chromatography ◽  
Refractive Index ◽  
Fatty Acid ◽  
Potassium Hydroxide ◽  
High Performance ◽  
Physicochemical Characterization ◽  
Physicochemical Characteristics ◽  
Total Phenolic

The aim of the study was to characterize the pulp oil of bacuri Attalea phalerata Mart. ex Spreng. (Arecaceae) according to official analytical methods. Total phenolic and carotenoids contents were evaluated by spectrophotometry, and tocopherols composition by high-performance liquid chromatography. The fatty acid profile was obtained through gas chromatography from samples transesterified with potassium hydroxide in methanol and n-hexane. According to the proximate composition, bacuri pulp contained 41.5 % carbohydrates and 39.2 % lipids. Regarding its physicochemical properties, the oil showed a free fatty acids content of 0.7 %, a peroxide value of 1.4 meq/kg, a refractive index of 1.463, an iodine number of 84.3 g I2/100 g, a saponification number of 193.5 mg KOH/g, an unsaponifiable matter of 0.5 %, and 48.7 h of oxidative stability. Total phenolic, carotenoids, and tocopherols contents recorded values of 2.4 mg GAE/g, 243.0 µg/g, and 86.8 mg/kg, respectively. The bacuri oil showed a fatty acid composition similar to olive oil and a high percentage of unsaturation, finding 67.3 % of monounsaturated acids, and 11.3 % of polyunsaturated acids. The main fatty acids were oleic (67.3 %), palmitic (13.3 %), and linoleic (10.5 %). Due to its physicochemical characteristics, bacuri oil has a great potential to be used in food preparations, such as salad oil or in margarine formulation.

scholarly journals Synthesis and Characterization of Crystalline NaY-Zeolite from Belitung Kaolin as Catalyst for n-Hexadecane Cracking

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 404 ◽  
Author(s):  
Yuni K. Krisnandi ◽  
Indah R. Saragi ◽  
Riwandi Sihombing ◽  
Rizki Ekananda ◽  
Indah P. Sari ◽  
...  
Keyword(s):  
High Performance ◽  
Colloidal Silica ◽  
Nay Zeolite ◽  
Percentage Yield ◽  
Structure Similarity ◽  
The One ◽  
Silica Synthesis ◽  
Nay Zeolites ◽  
Cracking Catalysts

Crystalline sodium Y (NaY) zeolite has been synthesized using alternative natural source of aluminate and silicate, extracted from natural Belitung kaolin. Prior to use, the natural kaolin was pretreated to obtain fragmented metakaolin and extracted silica. Synthesis was conducted with the addition of NaY gel (two types of NaY seeds were used, prepared from colloidal sillica or sodium silica water) using hydrothermal method for 21 h at 100 °C. The characterization on the as-synthesized zeolites confirmed that the one prepared using colloidal silica-seed has closer structure similarity to NaY zeolite that was synthesized using pro analysis silicate and aluminate sources. Thus, the rest of the synthesis of NaY was carried out using colloidal silica-NaY seed. The NaY zeolites then were converted to HY, through ammonium-exchange followed by calcination, to be tested as cracking catalysts using n-hexadecane as a probe molecule. It shows that HY from metakaolin and extracted silica gives high performance, i.e., n-hexadecane conversion of 58%–64%, also C5-C12 percentage yield and selectivity of 56%–62% and 98%. This work has shown the potential to utilize kaolin as alternative silicate aluminate sources for crystalline zeolite synthesis and to obtain inexpensive and environmentally friendly catalyst materials.

Factor III Coagulant Antigen - A Measurement Independent of Biological Activity

1979 ◽  
Author(s):  
J.E. Brown ◽  
C.L. Carton ◽  
C. Hougie
Keyword(s):  
Biological Activity ◽  
Factor Viii ◽  
Response Curve ◽  
Fluid Phase ◽  
Bovine Plasma ◽  
Protease Treatment ◽  
The Stability ◽  
The One ◽  
Bovine Factor

A fluid phase immunoradiometric assay (IRMA) specific for factor VIII coagulant antigen determinants (VIII:CAg) employing a human Fab’ fraction antibody has been used to assay purified bovine factor VIII. Bovine plasma, although 8-10 times as active in the one-stage clotting assay for VIII:C is only 40% as relative to human plasma in the in VIII:CAg and exhibits a parallel dose response curve. Thrombin (0.1 units/ml) enhances purified bovine VIII:C 20-fold or more but shows no effect on VIII:CAgΛ higher thrombin concentration (30 units/ml) destroys 97% of the VIII:C activity but only about 30% of the VIII:CAg. Similarly, both human and bovine serum retain about 70% of the VIII:CAg relative to the respective plasma levels. Trypsin (5 ug/ml1 hr 1 destroyed over 99.5% of the factor VIII:C in a purified bovine factor VIII preparation., but left a similarly high (70-90%) level of VIIl:CAg. EDTA-aged plasma used as an artificial substrate for factor VIII:C contains an undiminished level of VIII:CAg, but heated plasma (56°, 1 hr.) showed parallel losses (over 95%) of both VIII:C and VIII:CAg. The stability of factor VIII:CAg to protease treatment should permit characterization of purified factor VIII in caaes where biological activity is absent

Degradation Behavior of Poly(ethylene glycol) Diblock and Multiblock Polymers with Hydrolytically Degradable Ester Linkages

2004 ◽  
Vol 69 (8) ◽  
pp. 1643-1656 ◽  
Author(s):  
Alena Braunová ◽  
Michal Pechar ◽  
Karel Ulbrich
Keyword(s):  
Ethylene Glycol ◽  
Hydrolytic Degradation ◽  
Dicarboxylic Acids ◽  
Drug Carriers ◽  
Poly Ethylene Glycol ◽  
Model Study ◽  
Alkaline Conditions ◽  
Rate Of Hydrolysis ◽  
Poly Ethylene ◽  
The Stability

Diblock and multiblock polymers of poly(ethylene glycol) containing degradable ester bonds between the blocks were synthesized and characterized. Monofunctional poly(ethylene glycol) (PEG 2000) was modified by aliphatic dicarboxylic acids (malonic, succinic, glutaric, maleic) to obtain monocarboxylic polymers PEG-COOH containing ester bonds. Diblock polymers (4000) were prepared by polycondensation of a diamine (ethane-1,2-diamine, L-lysine) and the semitelechelic PEG-COOH. The relationship between the structure of the linkage connecting two PEG blocks and the rate of its hydrolytic degradation was studied at pH 5.5, 7.4 and 8.0. The rate of hydrolysis of all polymers was significant already under mild alkaline conditions (pH 7.4 and 8.0) and increased with increasing pH. The ester bonds of polymers with saturated dicarboxylic acid moieties were stable at pH 5.5. However, the presence of double bond in the acid moiety substantially decreased the stability of the polymer not only in alkaline but also in acid medium. The results of this model study can be utilized in the design of biodegradable high-molecular-weight drug carriers and polymers for preparation of "stealth" systems intended for therapeutic application.

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