1,721,201 research outputs found
Il Sistema Universitario Campano tra Miti e Realtà: Aspetti Metodologici, Analisi e Risultati
No full textProduction of PEG-coated liposomes using a continuous supercritical assisted process
No full textLiposomes are spherical vesicles, characterized by spontaneous aggregation tendency. To overcome this problem, in this work, liposomes coating was attempted, using polyethylene glycol (PEG), at different polymer to lipid ratios (1, 5, 10 % w/w) and proposing two experimental protocols, based on a supercritical assisted process. Only one protocol was successful; in that case, size and SEM analysis confirmed that vesicles did not aggregate thanks to the repulsion created by PEG surface, as confirmed by zeta potential measurements (about -25 mV). Liposomes with mean size ranging between 134 ± 30 and 166 ± 45 nm, stable for at least 70 day, were produced. The efficiency of SuperLip to produce PEG-coated liposomes was also tested, entrapping artesunate, obtaining encapsulation efficiencies up to 92 %. Drug release tests for standard and PEG-coated liposomes were compared: PEGylated vesicles produced a controlled release at least three times longer, without a significant initial burst release
Supercritical fluid processing of polymers
No full textThe use of supercritical fluids instead of organic solvents has attracted the interest of numerous researchers, due to the unique peculiarities of supercritical fluids which are characterized by solvent powers comparable to those of liquid organic solvents, diffusivity comparable to those of gaseous substances and quasi-zero surface tension [...]
Preparation, Characterization and Stability Evaluation of Alpha-Tocopherol Nanosuspensions Produced using a New Supercritical Assisted Process
No full textSupercritical CO2 assisted strategy for acetic acid elimination from industrial cellulose acetate–water mixtures
No full textA critical analysis of the major steps involved in the cellulose acetate industrial process is performed, with the aim of proposing possible improvements using supercritical CO2 based sub-processes. Once highlighted the main weakness of the traditional process, related to the (i) fine modulation of the acetylation reaction to obtain 2.5 acetate, (ii) acetic acid removal from the acetic dope, and (iii) treatment of the diluted acetic acid–water solution, the most attractive alternative resulted the adoption of a supercritical antisolvent extraction (SAE) performed on the acetic dope. Operating in this way, the problems related to the use of large quantities of water to remove acetic acid from the acetic dope are resolved, since it will be directly extracted by supercritical CO2. Micro- and nanoparticles, or filaments, of cellulose acetate can be produced. Finally, an acetic acid residue of 23 ppm, in the supercritical CO2 treated cellulose acetate, confirmed the success of this alternative process configuration
Isolation of rosemary oil: comparison between hydrodistillation and supercritical carbon dioxide extraction.
No full textNiosomes formation using a continuous supercritical CO2 assisted process
No full textThe production of biocompatible nanocarriers, to induce a controlled, sustained and/or targeted drug delivery, is a fascinating nanotechnology challenge. Among the possible nanocarriers, niosomes are non-ionic compounds, with a lipophilic tail and a hydrophilic head, that can self-assemble in aqueous dispersions and can show a good stability over time. In this work, a continuous process, assisted by supercritical CO2, was used for the production of empty and theophylline loaded niosomes. The optimal results, in terms of niosomes nanometric dimension and stability verified up to 30 days, were obtained processing an ethanolic solution at a 90/10 Span® 80 to Tween® 80 ratio. A drug encapsulation efficiency of 85 % was measured when the supercritical process was carried out using a water flow rate of 1 mL/min. Theophylline release time was prolonged up to 5-folds, when this active compound was loaded in niosomes prepared at the largest surfactant to water ratio (100 mg/g)
Supercritical fluid extraction of compounds of pharmaceutical interest from Wendita calysina (burrito)
No full textWendita calysina (commonly known as burrito) is an indigenous Paraguayan medical plat, whose essential oil (EO) is characterized by some pharmaceutical properties. In particular, the main component is D-carvone, with anticancer action and antimicrobial properties against various microorganisms. In this work, supercritical CO2 (SC-CO2) was used for the extraction of volatile compounds from this plant, selecting different operative conditions to optimize the extract yield and purity. Pressure was varied from 80 to 250 bar, and two CO2 flow rates (0.8 kg/h and 1.2 kg/h) were tested. The highest EO percentage in the extract was obtained operating at 100 bar and 40 °C, using ground Wendita calysina leaves of 250 μm. CO2 flow rate did not influence the extraction yield, indicating that an internal mass transfer resistance governs this process. The largely prevailing compound identified in the extract was D-carvone, with a mean percentage up to 90% w/w
Instantaneous coprecipitation of polymer/drug microparticles using the supercritical assisted injection in a liquid antisolvent
No full textIn this work, the supercritical assisted injection in a liquid antisolvent (SAILA) has been proposed as a new technique to produce composite microparticles for drug controlled release. Coprecipitation has been attempted for different non-steroidal anti-inflammatory drugs (Diclofenac, DF, Piroxicam, PX, and Indomethacin, ID) using poly-lactic-co-glycolic (PLGA) as the polymer matrix; acetone has been used as the liquid solvent and water as the liquid antisolvent. Coprecipitation was successful in all the cases and encapsulation efficiency ranged between 50 and 97%. The effect of operating parameters, such as the polymer/drug ratio, polymer concentration, injection temperature and pressure on particle morphology and drug release rate has been studied considering the system PLGA/Piroxicam. SEM analysis indicated that non-coalescing spherical microparticles formed by PLGA/PX were produced by SAILA at fast mixing conditions (higher injection pressure and higher temperature) and high polymer/drug ratios (20/1 and 10/1). All coprecipitates showed a sharp particle distribution, with diameters ranging between about 0.28 and 2.50 Î1⁄4m. SAILA composite microparticles have been characterized by X-ray, FT-IR, EDX and UVâvis analysis. PLGA/PX coprecipitates showed a prolonged release, about 7 times slower than the physical mixture of the same compounds; moreover, the polymer/drug ratio and the concentration of polymer in the solvent revealed to be a controlling parameter for drug release. The Hoffenberg's equation has been used to describe experimental data, showing a fair good agreement with PX release data
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