Maria I. Z. Lionzo

Microparticles prepared with poly(hydroxybutyrate-co-hydroxyvalerate) and poly(ε-caprolactone) blends to control the release of a drug model

The objective of this work was to verify the influence of the poly(ϵ-caprolactone) PCL concentration in poly(hydroxybutyrate-co-hydroxyvalerate) P(HBHV)/PCL microparticles, prepared by an emulsion/solvent evaporation process, on the release behavior of a drug. Differential Scanning Calorimetry analyses demonstrated that the preparation process increased the crystallite heterogeneity for the P(HBHV) in the particles. The drug caused an increase in the glass transition of the P(HBHV) in the microparticles. Dexamethasone acetate-loaded microparticles demonstrated drug sustained releases (up to 250 h), which profiles fit the biexponential model. The release of dexamethasone acetate caused an increase in the surface area of the microparticles. The kinetic constants of the sustained phase increased with the augmentation of the PCL content in the blend. The drug release mechanism was dependent on the presence of PCL in the microparticles. A Fickian release was determined for the microparticles prepared exclusively with P(HBHV), while non-Fickian release behaviors were found for the P(HBHV)/PCL microparticles.

Surface morphology of spray-dried nanoparticle-coated microparticles designed as an oral drug delivery system

This paper was devoted to studying the influence of coating material (nanocapsules or nanospheres), drug model (diclofenac, acid or salt) and method of preparation on the morphological characteristics of nanoparticle-coated microparticles. The cores of microparticles were obtained by spray drying or evaporation and the coating was applied by spray drying. SEM analyses showed nanostructures coating the surface of nanocapsule-coated microparticles and a rugged surface for nanosphere-coated microparticles. The decrease in their surface areas was controlled by the nanoparticulated system, which was not dependent on microparticle size. Optical microscopy and X-ray analyses indicated that acid diclofenac crystals were present in formulations prepared with the acid as well as in the nanocapsule-coated microparticles prepared with the salt. The control of coating is dependent on the use of nanocapsules or nanospheres and independent of either the characteristics of the drug or the method of preparing the core.

Avaliação da redução da carga microbiana de droga vegetal através do processamento tecnológico: decocção e secagem por aspersão

As plantas medicinais podem representar importantes alternativas terapeuticas. No entanto, para elaboracao de um fitoterapico a contaminacao microbiana constitui um problema a ser vencido. O processamento tecnologico da materia-prima envolve etapas, geralmente, desfavoraveis a sobrevivencia de microrganismos, sendo sua eliminacao dependente da carga microbiana inicial e das condicoes de trabalho utilizadas. Assim, este estudo teve como objetivo verificar a contaminacao microbiana presente nas partes aereas de Phyllanthus niruri e produtos derivados, solucao extrativa (SE) e produto seco por aspersao (PSA), a fim de avaliar a reducao da contaminacao apos a decoccao e a secagem por aspersao. A determinacao dos microrganismos viaveis nos produtos foi realizada atraves do metodo de contagem em placas, e a quantificacao de coliformes totais pela tecnica do numero mais provavel. Os resultados demonstraram que carga microbiana dos produtos analisados encontrava-se abaixo do limite maximo permitido. Em relacao a droga vegetal, a solucao extrativa apresentou carga microbiana consideravelmente menor, sugerindo que a decoccao tenha sido responsavel pela reducao de 98,3% da contaminacao inicial. Por outro lado, a carga microbiana do PSA foi semelhante a da SE, indicando que os microrganismos nao sao afetados pela operacao de secagem por aspersao.

Phospholipid/chitosan self‐assemblies analyzed by SAXS and Light Scattering

Self‐assemblies of phospholipids in an organic solvent (ethyl acetate) and their interaction with a cationic polysaccharide (chitosan) were appraised by scattering techniques. The investigations allowed following the formation of the self‐assemblies and their dimensions as a function of components concentration over time.

Chitosan as Stabilizer and Carrier of Natural Based Nanostructures

The use of nanotechnology in the development of cosmetics can bring new sights to old approaches. Liposomes are classic nanostructured systems largely used because of their ability to entrap hydrophilic and hydrophobic active substances. However, new materials can be obtained by the association of such classical devices with other materials, like the polyelectrolyte chitosan. In this way, chitosan can be used to modulate the surface properties of liposomes. The large surface area makes crucial the knowledge about interfacial phenomena for systems that contain nanoparticles. On the other hand, the macroscopic properties, e.g. rheology, can be modified by the association of chitosan and nanoparticles, affecting sensory attributes. Finally, on the biomedical field it is also possible to produce new devices to be used as support to growth cells employing the same strategy. By analyzing some fundamental aspects of the nanoparticles as well as their carrier it is possible to bring new and better systems based on chitosan.

The influence of chondroitin sulfate on composite multilamellar liposomes containing chitosan

A composite multilamellar liposome containing chitosan attached to the inside and outside of the membrane as well as an opposite charged polyelectrolyte, chondroitin, adsorbed at the surface was developed. Not only the chitosan/chondroitin ratio but also the concentration of them were varied. The structure and superficial properties of the liposomes were studied through a combination of light scattering, zeta potential, and small-angle X-rays scattering techniques. While the chitosan/chondroitin ratio affected the superficial charge distributions, the concentration of polyelectrolytes affected the structural properties of the liposomes, as the rigidity of the phospholipid layers. The superficial charge of the resultant composite liposome was influenced by the type and concentration of the polyelectrolyte. Information about the charge density could be obtained by the treatment of zeta potential data, and it was used to estimate the amount of chondroitin adsorbed to the liposome surface. Applying the modified Caillé theory to the X-rays scattering curves, information about the internal structure of the liposomes was accessed. The ability to control the properties of composite multilamellar liposomes is an important issue when they have to be applied as a biomaterial device component.