1,720,992 research outputs found
The Nanostructure of Polymer‐Active Principle Microparticles Produced by Supercritical CO2 Assisted Processing
No full textTraditional and supercritical CO2 assisted processes are frequently used to produce mi-croparticles formed by a biopolymer containing an active principle to improve the bioavailability of the active principle. However, information about the internal organization of these microparticles is still scarce. In this work, a suspension of dextran + Fe3O4 nanoparticles (model system) and a solution of polyvinylpyrrolidone (PVP) + curcumin were used to produce spherical microparticles by supercritical CO2 processing. Periodic dynamic light scattering measurements were used to analyze the evolution of the microparticles dissolution, size, and size distribution of the guest active principle in the polymeric matrix. It was found that curcumin was dispersed in the form of nanoparticles in the PVP microparticles, whose size largely depended on its relative concentration. These results were validated by transmission electron microscopy and scanning electron microscopy of the PVP microparticles and curcumin nanoparticles, before and after the dissolution tests
Lycopene extract from tomato concentrate and its co-precipitation with PVP using hybrid supercritical processes
No full textIn this work, a hybrid supercritical approach was proposed for the production of a dried lycopene extract and its co-precipitation in polyvinylpyrrolidone (PVP) sub-microparticles. In particular, lycopene extract was obtained from a tomato pulp concentrate, using ethyl acetate as the optimal organic solvent. Then, the lycopene extract was dried via supercritical antisolvent extraction, operating at 9.0 MPa and 50 °C. In a single step, a solvent-free powder that preserved up to 80 % of antioxidant activity was obtained. To improve lycopene extract shelf-life, supercritical assisted atomization was performed. The aim was to co-precipitate the active principle with a hydrophilic polymer, like PVP, to protect lycopene from oxidation phenomena. Operating at 8.5 MPa and 80 °C, sub-microparticles of 194 ± 230 nm mean diameter were produced that maintained around 85 % of antioxidant activity at least for 6 months of storage at room temperature
Supercritical fluid assisted process for the generation of cellulose acetate loaded structures, potentially useful for tissue engineering applications
No full text3D PLLA/ibuprofen composite scaffolds obtained by a supercritical fluids assisted process
No full textThe emerging next generation of engineered tissues is based on the development of loaded scaffolds containing bioactive molecules in order to control the cellular function or to interact on the surrounding tissues. Indeed, implantation of engineered biomaterials might cause local inflammation because of the host's immune response; thereby, the use of anti-inflammatory agents, whether steroidal or nonsteroidal is required. One of the most important stages of tissue engineering is the design and the generation of a porous 3D structure, with high porosity, high interconnectivity and homogenous morphology. Various techniques have been reported in the literature for the fabrication of biodegradable scaffolds, but they suffer several limitations. In this study, for the first time, the possibility of generating 3D polymeric scaffolds loaded with an active compound by supercritical freeze extraction process is evaluated; this innovative process combines the advantages of the thermally induced phase separation process and of the supercritical carbon dioxide drying. Poly-L-lactid acid/ibuprofen composite scaffolds characterized by a 3D geometry, micrometric cellular structures and wrinkled pores walls have been obtained; moreover, homogeneous drug distribution and controlled release of the active principle have been assured
Use of a supercritical fluids assisted process to generate cellulose acetate loaded membranes for controlled release applications
No full textFractionation of Marigold Waxy Extract Using Supercritical CO2
No full textMarigold oil is a product of great industrial interest thanks to its wide range of medicinal and wound-healing properties. In this work, supercritical carbon dioxide was used to recover marigold essential oil from the hexane solvent extract of marigold flowers, the floral “concrete”. This starting material was mixed with synthetic paraffinic waxes to heighten its melting point and viscosity, thus, improving material processability. Supercritical fluid extraction and fractionation of the modified marigold “concrete” was carried out, and the effect of pressure and CO2 mass flow rate was studied. The pressure was varied from 80 to 180 bar, keeping the temperature constant at 40 °C: the higher the pressure, the larger the CO2 solvent power and extraction yield (up to 9.40% w/w). Nevertheless, the optimum between productivity and process selectivity was found at 100 bar. By changing the CO2 mass flow rate (from 1.20 to 1.50 kg/h), we noted that mass transfer resistance was located externally. GC-MS analysis showed that the most abundant compounds in the oil were δ-cadinene (25%), γ-cadinene (16%), τ-muurolol (6.5%), and α-muurolene (6%). Moreover, the traces of oil and waxes showed no mutual contamination between lighter species and waxes, meaning that the fractionation step was successful
Production of cannabidiol nanoparticles loaded in polyvinylpyrrolidone microparticles by supercritical CO2 assisted atomization and dissolution enhancement effect
No full textIn this work, cannabidiol (CBD) nanoparticles contained in polyvinylpyrrolidone (PVP) microparticles (nano-in-micro system) were produced by supercritical CO2 assisted atomization (SAA) with the aim of improving CBD bioavailability. The experiments were performed by changing the total concentration of solute PVP + CBD and CBD/PVP mass ratio (R) to understand the effect of these parameters on CBD nanoparticle mean size, measured by a dynamic light scattering operating in a periodic manner. Nanoparticles as small as 33 nm were obtained, protected in PVP microparticles. CBD release tests were carried out to verify the increase in the solubilization rate of CBD nanoparticles: pure CBD powder was completely dissolved in about 240 min; whereas CBD 55 nm nanoparticles were completely released in 20 min
A new tool to produce alginate-based aerogels for medical applications, by supercritical gel drying
No full textAlginate-based aerogels with a cylindrical shape to be used for medical applications were produced by supercritical drying. First, alginate (Alg) solutions at different polymer concentrations (from 5% to 15% w/w) were extruded using a new custom-made device, in a coagulation bath of CaCl2 at 5% w/w or CuSO4 at 1.5% w/v, where hydrogels were generated; then, the corresponding aerogels were produced by supercritical drying at 200 bar and 45 °C for 4 h. Scanning electron microscopy showed that nanostructured morphology of native Ca- and Cu-Alg-hydrogels was preserved by supercritical drying. The same apparatus was also tested to produce alginate-chitosan (Alg-Ch) aerogels; they showed an hybrid morphology characterized by the microporosity of chitosan and the nanofibers of alginate, homogeneously distributed in the gel structure
Extraction of rotenoids from Derris elliptica using supercritical CO2
No full textBACKGROUND: Supercritical (SC)-CO2 extraction of rotenoids from Derris elliptica roots was proposed using fractional separation of the extracts and operating at increasing pressure. RESULTS: The best processing conditions were found at 200 bar, 40 °C and 1.2 kg h−1 SC-CO2 flow rate, obtaining a final product with a concentration of 93% w/w of rotenone and rotenoids, and a yield of active principles of 6.70% w/w with respect to the vegetable matrix. Very small quantities of waxes were found, up to 0.05% w/w; this result can be explained considering the reduced surface-to-volume ratio of this vegetable material. CONCLUSION: Extraction kinetics data confirmed that, in this case, the extraction process was controlled by solubility limitation of the active compounds in the supercritical solvent
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