Physicochemical and morphological characterizations of glyceryl tristearate/castor oil nanocarriers prepared by the solvent diffusion method

Neste estudo, nanocarreadores lipidicos foram preparados a partir do triestearato de glicerila e oleo de ricino em diferentes proporcoes pela tecnica de difusao do solvente a quente. Estearato de PEG-660 ou Poloxamer 188 e lecitina de soja foram usados como surfactante e cossurfactante, respectivamente. Caracteristicas estruturais e fisico-quimicas das particulas foram investigadas por meio de espalhamento de luz dinâmico (DLS), calorimetria exploratoria diferencial (DSC), espalhamento de raios X a altos ângulos (WAXS), microscopia de forca atomica (AFM) e microscopia eletronica de transmissao (TEM e cryo-TEM). A analise por DLS indicou que particulas menores foram obtidas quando o lipidio liquido foi usado sozinho para obter as nanoemulsoes (NEs). Tecnicas microscopicas (TEM e cryo-TEM) mostraram que as NEs apresentaram formas esfericas, enquanto as nanoparticulas lipidicas solidas (NLSs) e os carreadores lipidicos nanoestruturados (CLNs) apresentaram formas mais complexas. As NLSs exibiram estrutura cristalina lamelar, enquanto os CLNs exibiram uma estrutura mista composta de fase cristalina lamelar em contato com compartimento oleoso. Estes experimentos contribuem para um melhor entendimento da capacidade de incorporacao e liberacao de farmacos destes nanocarreadores. In this study, drug delivery nanocarriers based on glyceryl tristearate and castor oil at different ratios were prepared by the hot solvent diffusion method. PEG 660-stearate or Poloxamer 188 and soybean lecithin were used as surfactant and co-surfactant, respectively. Structural and physicochemical characteristics of the particles were investigated by means of dynamic light scattering (DLS), differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), atomic force microscopy (AFM) and transmission electron microscopy (TEM and cryo-TEM). DLS data indicated that smaller particles were obtained when the liquid lipid was used alone to prepare nanoemulsions (NEs). TEM and cryo-TEM images showed that NEs presented spherical particles, whereas solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) presented more complex shapes. SLNs exhibited lamellar crystal structure, while NLCs displayed a hybrid structure composed of a lamellar crystalline phase in contact with a liquid oil compartment. These experiments contribute to a better understanding of the structure and release performance of these drug carrier systems.