RESUMEN

Hydrophobic bioactives can be more easily incorporated into food and have their bioavailability enhanced if nanostructured lipid carriers (NLC) are used as carriers. In the present study, beta-carotene-loaded NLC were produced by low emulsification using murumuru butter and a mixture of Span 80 and Cremophor RH40 as surfactants. Their average diameter was 35 nm and alpha-tocopherol was required to protect the encapsulated ß-carotene. Besides the evaluation of their physicochemical stability, NLC were submitted to dynamic in vitro digestion and cell viability assays with Caco-2 and HEPG cells. The bioaccessibility of beta-carotene in the dynamic system was about 42%. Regarding cell viability, results indicated NLC were toxic to the cell cultures tested. Such high toxicity is probably related to the type of surfactant used and to the extremely reduced particle size, which may have led to an intense and fast permeation of the NLC through the cells.

Asunto(s)

Antioxidantes/administración & dosificación , Portadores de Fármacos/química , Lípidos/química , Provitaminas/administración & dosificación , alfa-Tocoferol/administración & dosificación , beta Caroteno/administración & dosificación , Antioxidantes/química , Células CACO-2 , Supervivencia Celular/efectos de los fármacos , Portadores de Fármacos/toxicidad , Combinación de Medicamentos , Humanos , Lípidos/toxicidad , Magnoliopsida/química , Nanoestructuras/química , Nanoestructuras/toxicidad , Transición de Fase , Provitaminas/química , Temperatura de Transición , alfa-Tocoferol/química , beta Caroteno/química

RESUMEN

Multilamellar liposomes incorporating essential oil of Brazilian cherry (Eugenia uniflora L.) leaves were produced by dry film hydration. Gas chromatography demonstrated the compounds found in the essential oil were effectively incorporated in the aqueous dispersions of liposomes. Differential scanning calorimetry analyses revealed the incorporation of the essential oil did not cause phase separation in the membrane structure; the gel-liquid crystalline transition temperature (main transition) remained the same despite the higher heterogeneity indicated by the transition peak broadening. Different cryoprotectors (sucrose and trehalose) were added to the liposomal formulations to be tested in their ability to protect the liposomal structure during the lyophilization. The morphological aspect of the lyophilized powders analysed by scanning electron microscopy showed significant differences among the samples with and without cryoprotectors. Fourier-transform infrared spectroscopy indicated the cryoprotectors interacted effectively with the polar heads of phospholipids in the bilayer. In terms of water absorption, trehalose was identified as a much more effective protector agent against it than sucrose. The cryoprotectors showed different degrees of effectiveness of preservation of the liposomal structure when the rehydration assays of lyophilized liposomes were carried out, as particle size measurements indicated a moderate process of fusion when the formulations with sucrose were rehydrated.

Asunto(s)

Liposomas/química , Aceites Volátiles/administración & dosificación , Aceites Volátiles/química , Syzygium/química , Rastreo Diferencial de Calorimetría , Crioprotectores , Composición de Medicamentos , Liofilización , Microscopía Electrónica de Rastreo , Aceites Volátiles/aislamiento & purificación , Hojas de la Planta/química , Espectroscopía Infrarroja por Transformada de Fourier , Agua/química

RESUMEN

The aim of this study was to compare qualitative and quantitative methods for coating characterization on internal surfaces of polyvinyl chloride (PVC) tubing used in procedures of extracorporeal circulation. The methods of characterization included optical microscopy (OM) after dyeing with toluidine blue, scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive spectrometry (EDS). OM after sample dyeing was excellent in allowing early detection of any absence or irregularities of coatings among the used methods. SEM was the most effective in observing the structure and thickness either in heparin coatings or in lipid coatings. AFM provided a good evaluation of the surface topography. A conjunction of all methods is recommended for complete characterization. The quantification methods based on colorimetric tests were efficient in determining the concentrations of heparin and lipid on internal surface tubes, the coating stability and the reproducibility of the results.