769 resultados para microcrystalline chitosan
Resumo:
Triheptanoin-enriched diets have been successfully used in the experimental treatment of various metabolic disorders. Maximal therapeutic effect is achieved in the context of a ketogenic diet where triheptanoin oil provides 3040% of the daily caloric intake. However, pre-clinical studies using triheptanoin-rich diets are hindered by the difficulty of administering to laboratory animals as a solid foodstuff. In the present study, we successfully synthesized triheptanoin to the highest standards of purity from glycerol and heptanoic acid, using sulfonated charcoal as a catalyst. Triheptanoin oil was then formulated as a solid, stable and palatable preparation using a ketogenic base and a combination of four commercially available formulation agents: hydrophilic fumed silica, hydrophobic fumed silica, microcrystalline cellulose, and talc. Diet compliance and safety was tested on C57Bl/6 mice over a 15-week period, comparing overall status and body weight change. Practical applications: This work provides a complete description of (i) an efficient and cost-effective synthesis of triheptanoin and (ii) its formulation as a solid, stable, and palatable ketogenic diet (triheptanoin-rich; 39% of the caloric intake) for rodents. Triheptanoin-rich diets will be helpful on pre-clinical experiments testing the therapeutic efficacy of triheptanoin in different rodent models of human diseases. In addition, using the same solidification procedure, other oils could be incorporated into rodent ketogenic diet to study their dosage and long-term effects on mammal health and development. This approach could be extremely valuable as ketogenic diet is widely used clinically for epilepsy treatment.
Resumo:
Triheptanoin-enriched diets have been successfully used in the experimental treatment of various metabolic disorders. Maximal therapeutic effect is achieved in the context of a ketogenic diet where triheptanoin oil provides 3040% of the daily caloric intake. However, pre-clinical studies using triheptanoin-rich diets are hindered by the difficulty of administering to laboratory animals as a solid foodstuff. In the present study, we successfully synthesized triheptanoin to the highest standards of purity from glycerol and heptanoic acid, using sulfonated charcoal as a catalyst. Triheptanoin oil was then formulated as a solid, stable and palatable preparation using a ketogenic base and a combination of four commercially available formulation agents: hydrophilic fumed silica, hydrophobic fumed silica, microcrystalline cellulose, and talc. Diet compliance and safety was tested on C57Bl/6 mice over a 15-week period, comparing overall status and body weight change. Practical applications: This work provides a complete description of (i) an efficient and cost-effective synthesis of triheptanoin and (ii) its formulation as a solid, stable, and palatable ketogenic diet (triheptanoin-rich; 39% of the caloric intake) for rodents. Triheptanoin-rich diets will be helpful on pre-clinical experiments testing the therapeutic efficacy of triheptanoin in different rodent models of human diseases. In addition, using the same solidification procedure, other oils could be incorporated into rodent ketogenic diet to study their dosage and long-term effects on mammal health and development. This approach could be extremely valuable as ketogenic diet is widely used clinically for epilepsy treatment.
Resumo:
Triheptanoin-enriched diets have been successfully used in the experimental treatment of various metabolic disorders. Maximal therapeutic effect is achieved in the context of a ketogenic diet where triheptanoin oil provides 3040% of the daily caloric intake. However, pre-clinical studies using triheptanoin-rich diets are hindered by the difficulty of administering to laboratory animals as a solid foodstuff. In the present study, we successfully synthesized triheptanoin to the highest standards of purity from glycerol and heptanoic acid, using sulfonated charcoal as a catalyst. Triheptanoin oil was then formulated as a solid, stable and palatable preparation using a ketogenic base and a combination of four commercially available formulation agents: hydrophilic fumed silica, hydrophobic fumed silica, microcrystalline cellulose, and talc. Diet compliance and safety was tested on C57Bl/6 mice over a 15-week period, comparing overall status and body weight change. Practical applications: This work provides a complete description of (i) an efficient and cost-effective synthesis of triheptanoin and (ii) its formulation as a solid, stable, and palatable ketogenic diet (triheptanoin-rich; 39% of the caloric intake) for rodents. Triheptanoin-rich diets will be helpful on pre-clinical experiments testing the therapeutic efficacy of triheptanoin in different rodent models of human diseases. In addition, using the same solidification procedure, other oils could be incorporated into rodent ketogenic diet to study their dosage and long-term effects on mammal health and development. This approach could be extremely valuable as ketogenic diet is widely used clinically for epilepsy treatment.
Resumo:
Heusler alloy Mn50Ni40In10 was produced as preferentially textured ribbon flakes by melt spinning, finding the existence of martensitic-austenic transformation with both phases exhibiting ferromagnetic ordering. A microcrystalline three-layered microstructure of ordered columnar grains grown perpendicularly to ribbon plane was formed between two thin layers of smaller grains. The characteristic temperatures of the martensitic transformation were MS=213 K, Mf=173 K, AS=222 K, and Af=243 K. Austenite phase shows a cubic L21 structure (a=0.6013(3) nm at 298 K and a Curie point of 311 K), transforming into a modulated fourteen-layer modulation monoclinic martensite
Resumo:
The nanoparticles developed are based on chitosan, a biocompatible and biodegradable polysaccharide. The chitosan nanoparticles are formed in an entirely water-based process by electrostatic interactions with other biocompatible molecules. As a prerequisite to understand the fate of such nanoparticles in cells, comprehensive characterization and stability studies serve to identify quantitatively the impact of the raw material characteristics and preparation conditions on the nanoparticle characteristics. Methods included H-1 NMR spectroscopy, dilution viscometry, particle size analysis and electron microscopy. Cytotoxicity and cell uptake experiments on RAW 264.7 murine macrophages and p23 murine endothelial cells were performed to investigate the correlation with nanoparticle characteristics and effect of surface decoration with alginate. Cytotoxicity was assessed by the MTT survival test; cell uptake was monitored by fluorescent microscopy using labeled polymers.
Resumo:
The compounds responsible for the colours and decorations in glass and glazed ceramics include: colouring agents (transition metal ions), pigments (micro-and nano-precipitates of compounds that either do not dissolve or recrystallize in the glassy matrix) and opacifiers (microcrystalline compounds with high light scattering capability). Their composition, structure and range of stability are highly dependent not only on the composition but also on the procedures followed to obtain them. Chemical composition of the colorants and crystallites may be obtained by means of SEM-EDX and WDX. Synchrotron Radiation micro-X-ray Diffraction has a small beam size adequate (10 to 50 microns footprint size) to obtain the structural information of crystalline compounds and high brilliance, optimal for determining the crystallites even when present in low amounts. In addition, in glass decorations the crystallites often appear forming thin layers (from 10 to 100 micrometers thick) and they show a depth dependent composition and crystal structure. Their nature and distribution across the glass/glazes decorations gives direct information on the technology of production and stability and may be related to the color and appearance. A selection of glass and glaze coloring agents and decorations are studied by means of SR-micro- XRD and SEM-EDX including: manganese brown, antimony yellow, red copper lusters and cobalt blue. The selection includes Medieval (Islamic, and Hispano Moresque) and renaissance tin glazed ceramics from the 10th to the 17th century AD.
Resumo:
The Heusler alloy Ni50 Mn37 Sn13 was successfully produced as ribbon flakes of thickness around 7-10 μm melt spinning. Fracture cross section micrographs in the ribbon show the formation of a microcrystalline columnarlike microstructure, with their longer axes perpendicular to the ribbon plane. Phase transition temperatures of the martensite-austenite transformation were found to be MS =218 K, Mf =207 K, AS =224 K, and Af =232 K; the thermal hysteresis of the transformation is 15 K. Ferromagnetic L 21 bcc austenite phase shows a Curie point of 313 K, with cell parameter a=0.5971 (5) nm at 298 K, transforming into a modulated 7M orthorhombic martensite with a=0.6121 (7) nm, b=0.6058 (8) nm, and c=0.5660 (2) nm, at 150 K
Resumo:
[spa]Objetivo: El objetivo de este estudio es el diseño de un parche bucoadhesivo para la administración transbucal de clorhidrato de doxepina utilizando diferentes polímeros así como la caracterización de dichos sistemas en cuanto al análisis calorimétrico y la capacidad de hinchamiento.Materiales y métodos: Se ha utilizado clorhidrato de doxepina y diferentes polímeros, carboximetilcelulosa sódica, hidroxipropilmetilcelulosa y chitosan. La calorimetría diferencial de barrido (DSC) se ha realizado en un dispositivo Mettler FP 80 equipado con un horno FP 85 y la capacidad de hinchamiento utilizando placas de agar.Resultados: Se obtienen termogramas de los parches y las mezclas físicas donde se observan transiciones endotérmicas entre 30 y 120º C y el pico endotérmico del principio activo en las mezclas físicas binarias. La entalpía de deshidratación es similar en los polímeros de carboximetilcelulosa sódica y chitosan (281 J/g) siendo menor en la película de hidroxipropilmetilcelulosa (251 J/g), al igual que el porcentaje de hidratación donde se demuestra que los parches elaborados con hidroxipropilmetilcelulosa presenta menor tendencia a captar agua (55,91 %) frente al 67,04 % y 67,30 % de la carboximetilcelulosa sódica y chitosan, respectivamente.Conclusión: Los resultados obtenidos muestran que existe compatibilidad entre los componentes de la formulación y los datos de entalpía se correlacionan con los datos obtenidos en el ensayo de hinchamiento.[eng]The aim of this study is to design a bucoadhesive patch for the transbuccal administration of doxepin hydrochloride using different polymers as well as the characterization of these systems for calorimetric analysis and the swelling capacity. Materials and methods: Doxepin hydrochloride was used as well as various polymers; carboxymethylcellulose sodium, hydroxypropylmethyl cellulose and chitosan. Differential scanning calorimetry (DSC) was carried out using a Mettler FP 80 device equipped with a FP 85 oven and the swelling capacity using agar plates. Results: Thermograms obtained patches and physical mixtures where there are endothermic transitions between 30 and 120º C and the endothermic peak of the active principle in binary physical mixtures. Dehydration enthalpy is similar in polymers of carboxymethylcellulose sodium and chitosan (281 J/g), the film having less hydroxypropylmethylcellulose (251 J/g), the percentage of moisture shows that the patches prepared with hydroxypropylmethylcellulose have less tendency to collect water (55.91 %) compared to 67.04 % and 67.30 % with sodium carboxymethylcellulose and chitosan, respectively. Conclusion: The results show that there is compatibility between the components of the formulation and the enthalpy data correlate
Resumo:
Background: Nanoparticle (NPs) functionalization has been shown to affect their cellular toxicity. To study this, differently functionalized silver (Ag) and gold (Au) NPs were synthesised, characterised and tested using lung epithelial cell systems. Mehtods: Monodispersed Ag and Au NPs with a size range of 7 to 10 nm were coated with either sodium citrate or chitosan resulting in surface charges from ¿50 mV to +70 mV. NP-induced cytotoxicity and oxidative stress were determined using A549 cells, BEAS-2B cells and primary lung epithelial cells (NHBE cells). TEER measurements and immunofluorescence staining of tight junctions were performed to test the growth characteristics of the cells. Cytotoxicity was measured by means of the CellTiter-Blue ® and the lactate dehydrogenase assay and cellular and cell-free reactive oxygen species (ROS) production was measured using the DCFH-DA assay. Results: Different growth characteristics were shown in the three cell types used. A549 cells grew into a confluent mono-layer, BEAS-2B cells grew into a multilayer and NHBE cells did not form a confluent layer. A549 cells were least susceptible towards NPs, irrespective of the NP functionalization. Cytotoxicity in BEAS-2B cells increased when exposed to high positive charged (+65-75 mV) Au NPs. The greatest cytotoxicity was observed in NHBE cells, where both Ag and Au NPs with a charge above +40 mV induced cytotoxicity. ROS production was most prominent in A549 cells where Au NPs (+65-75 mV) induced the highest amount of ROS. In addition, cell-free ROS measurements showed a significant increase in ROS production with an increase in chitosan coating. Conclusions: Chitosan functionalization of NPs, with resultant high surface charges plays an important role in NP-toxicity. Au NPs, which have been shown to be inert and often non-cytotoxic, can become toxic upon coating with certain charged molecules. Notably, these effects are dependent on the core material of the particle, the cell type used for testing and the growth characteristics of these cell culture model systems.
Resumo:
Triheptanoin-enriched diets have been successfully used in the experimental treatment of various metabolic disorders. Maximal therapeutic effect is achieved in the context of a ketogenic diet where triheptanoin oil provides 30-40% of the daily caloric intake. However, pre-clinical studies using triheptanoin-rich diets are hindered by the difficulty of administering to laboratory animals as a solid foodstuff. In the present study, we successfully synthesized triheptanoin to the highest standards of purity from glycerol and heptanoic acid, using sulfonated charcoal as a catalyst. Triheptanoin oil was then formulated as a solid, stable and palatable preparation using a ketogenic base and a combination of four commercially available formulation agents: hydrophilic fumed silica, hydrophobic fumed silica, microcrystalline cellulose, and talc. Diet compliance and safety was tested on C57Bl/6 mice over a 15-week period, comparing overall status and body weight change. Practical applications: This work provides a complete description of (i) an efficient and cost-effective synthesis of triheptanoin and (ii) its formulation as a solid, stable, and palatable ketogenic diet (triheptanoin-rich; 39% of the caloric intake) for rodents. Triheptanoin-rich diets will be helpful on pre-clinical experiments testing the therapeutic efficacy of triheptanoin in different rodent models of human diseases. In addition, using the same solidification procedure, other oils could be incorporated into rodent ketogenic diet to study their dosage and long-term effects on mammal health and development. This approach could be extremely valuable as ketogenic diet is widely used clinically for epilepsy treatment.
Resumo:
Triheptanoin-enriched diets have been successfully used in the experimental treatment of various metabolic disorders. Maximal therapeutic effect is achieved in the context of a ketogenic diet where triheptanoin oil provides 30-40% of the daily caloric intake. However, pre-clinical studies using triheptanoin-rich diets are hindered by the difficulty of administering to laboratory animals as a solid foodstuff. In the present study, we successfully synthesized triheptanoin to the highest standards of purity from glycerol and heptanoic acid, using sulfonated charcoal as a catalyst. Triheptanoin oil was then formulated as a solid, stable and palatable preparation using a ketogenic base and a combination of four commercially available formulation agents: hydrophilic fumed silica, hydrophobic fumed silica, microcrystalline cellulose, and talc. Diet compliance and safety was tested on C57Bl/6 mice over a 15-week period, comparing overall status and body weight change. Practical applications: This work provides a complete description of (i) an efficient and cost-effective synthesis of triheptanoin and (ii) its formulation as a solid, stable, and palatable ketogenic diet (triheptanoin-rich; 39% of the caloric intake) for rodents. Triheptanoin-rich diets will be helpful on pre-clinical experiments testing the therapeutic efficacy of triheptanoin in different rodent models of human diseases. In addition, using the same solidification procedure, other oils could be incorporated into rodent ketogenic diet to study their dosage and long-term effects on mammal health and development. This approach could be extremely valuable as ketogenic diet is widely used clinically for epilepsy treatment.
Resumo:
Hydrogenated microcrystalline silicon films obtained at low temperature (150-280°C) by hot wire chemical vapour deposition at two different process pressures were measured by Raman spectroscopy, X-ray diffraction (XRD) spectroscopy and photothermal deflection spectroscopy (PDS). A crystalline fraction >90% with a subgap optical absortion 10 cm -1 at 0.8 eV were obtained in films deposited at growth rates >0.8 nm/s. These films were incorporated in n-channel thin film transistors and their electrical properties were measured. The saturation mobility was 0.72 ± 0.05 cm 2/ V s and the threshold voltage around 0.2 eV. The dependence of their conductance activation energies on gate voltages were related to the properties of the material.
Resumo:
[spa]Objetivo: El objetivo de este estudio es el diseño de un parche bucoadhesivo para la administración transbucal de clorhidrato de doxepina utilizando diferentes polímeros así como la caracterización de dichos sistemas en cuanto al análisis calorimétrico y la capacidad de hinchamiento.Materiales y métodos: Se ha utilizado clorhidrato de doxepina y diferentes polímeros, carboximetilcelulosa sódica, hidroxipropilmetilcelulosa y chitosan. La calorimetría diferencial de barrido (DSC) se ha realizado en un dispositivo Mettler FP 80 equipado con un horno FP 85 y la capacidad de hinchamiento utilizando placas de agar.Resultados: Se obtienen termogramas de los parches y las mezclas físicas donde se observan transiciones endotérmicas entre 30 y 120º C y el pico endotérmico del principio activo en las mezclas físicas binarias. La entalpía de deshidratación es similar en los polímeros de carboximetilcelulosa sódica y chitosan (281 J/g) siendo menor en la película de hidroxipropilmetilcelulosa (251 J/g), al igual que el porcentaje de hidratación donde se demuestra que los parches elaborados con hidroxipropilmetilcelulosa presenta menor tendencia a captar agua (55,91 %) frente al 67,04 % y 67,30 % de la carboximetilcelulosa sódica y chitosan, respectivamente.Conclusión: Los resultados obtenidos muestran que existe compatibilidad entre los componentes de la formulación y los datos de entalpía se correlacionan con los datos obtenidos en el ensayo de hinchamiento.[eng]The aim of this study is to design a bucoadhesive patch for the transbuccal administration of doxepin hydrochloride using different polymers as well as the characterization of these systems for calorimetric analysis and the swelling capacity. Materials and methods: Doxepin hydrochloride was used as well as various polymers; carboxymethylcellulose sodium, hydroxypropylmethyl cellulose and chitosan. Differential scanning calorimetry (DSC) was carried out using a Mettler FP 80 device equipped with a FP 85 oven and the swelling capacity using agar plates. Results: Thermograms obtained patches and physical mixtures where there are endothermic transitions between 30 and 120º C and the endothermic peak of the active principle in binary physical mixtures. Dehydration enthalpy is similar in polymers of carboxymethylcellulose sodium and chitosan (281 J/g), the film having less hydroxypropylmethylcellulose (251 J/g), the percentage of moisture shows that the patches prepared with hydroxypropylmethylcellulose have less tendency to collect water (55.91 %) compared to 67.04 % and 67.30 % with sodium carboxymethylcellulose and chitosan, respectively. Conclusion: The results show that there is compatibility between the components of the formulation and the enthalpy data correlate
Resumo:
Adjuvants enhance immunogenicity of vaccines through either targeted antigen delivery or stimulation of immune receptors. Three cationic nanoparticle formulations were evaluated for their potential as carriers for a DNA vaccine, and muramyl dipeptide (MDP) as immunostimulatory agent, to induce and increase immunogenicity of Mycobacterium tuberculosis antigen encoding plasmid DNA (pDNA). The formulations included (1) trimethyl chitosan (TMC) nanoparticles, (2) a squalene-in-water nanoemulsion, and (3) a mineral oil-in-water nanoemulsion. The adjuvant effect of the pDNA-nanocomplexes was evaluated by serum antibody analysis in immunized mice. All three carriers display a strong adjuvant effect, however, only TMC nanoparticles were capable to bias immune responses towards Th1. pDNA naturally contains immunostimulatory unmethylated CpG motifs that are recognized by Toll-like receptor 9 (TLR-9). In mechanistic in vitro studies, activation of TLR-9 and the ability to enhance immunogenicity by simultaneously targeting TLR-9 and NOD-like receptor 2 (NLR-2) was determined by proinflammatory cytokine release in RAW264.7 macrophages. pDNA in combination with MDP was shown to significantly increase proinflammatory cytokine release in a synergistic manner, dependent on NLR-2 activation. In summary, novel pDNA-Ag85A loaded nanoparticle formulations, which induce antigen specific immune responses in mice were developed, taking advantage of the synergistic combinations of TLR and NLR agonists to increase the adjuvanticity of the carriers used.