The use of lipid nanoparticles as drug delivery systems has been growing over recent decades. Their biodegradable and biocompatible profile, capacity to prevent chemical degradation of loaded drugs/actives and controlled release for several administration routes are some of their advantages. Lipid nanoparticles are of particular interest for the loading of lipophilic compounds, as happens with essential oils. Several interesting properties, e.g., anti-microbial, antitumoral and antioxidant activities, are attributed to carvacrol, a monoterpenoid phenol present in the composition of essential oils of several species, including Origanum vulgare, Thymus vulgaris, Nigellasativa and Origanum majorana. As these essential oils have been proposed as the liquid lipid in the composition of nanostructured lipid carriers (NLCs), we aimed at evaluating the influence of carvacrol on the crystallinity profile of solid lipids commonly in use in the production of NLCs. Different ratios of solid lipid (stearic acid, beeswax or carnauba wax) and carvacrol were prepared, which were then subjected to thermal treatment to mimic the production of NLCs. The obtained binary mixtures were then characterized by thermogravimetry (TG), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS) and polarized light microscopy (PLM). The increased concentration of monoterpenoid in the mixtures resulted in an increase in the mass loss recorded by TG, together with a shift of the melting point recorded by DSC to lower temperatures, and the decrease in the enthalpy in comparison to the bulk solid lipids. The miscibility of carvacrol with the melted solid lipids was also confirmed by DSC in the tested concentration range. The increase in carvacrol content in the mixtures resulted in a decrease in the crystallinity of the solid bulks, as shown by SAXS and PLM. The decrease in the crystallinity of lipid matrices is postulated as an advantage to increase the loading capacity of these carriers. Carvacrol may thus be further exploited as liquid lipid in the composition of green NLCs for a range of pharmaceutical applications.
The aim of this work was to evaluate the effect of Ouratea sp. butter (OB) on crystallinity of solid lipids used in nanostructured lipid carriers systems. Firstly, the composition of fatty acids in OB was evaluated by transesterification reaction for gas chromatography fatty acid methyl ester analysis. The solid lipids such as stearic acid (SA), beeswax (BW) and carnauba wax (CW) were submitted to recrystallization process (heating-cooling). Moreover, binary mixtures between solid lipids and OB were prepared in ratio 1:1 (w/w) by heating of the components above the melting point followed by cooling at room temperature. Thus, the samples were characterized by differential scanning calorimetry (DSC), thermogravimetry (TG), X ray diffraction (XRD) and hot-stage polarized optical microscopy (HSPOM). DSC curves showed a shift of the melting point to lower temperatures in the lipid mixtures with OB. TG data suggested a thermal stability reduction in the lipid mixtures containing SA and CW and an increase thermal stability in the mixture containing BW. XRD data confirmed DSC results, showing a reduction in intensity of main diffraction peaks of the lipid mixtures and a presence of the amorphous portion in angle 2h: 22°. Finally, HSPOM demonstrated that the microstructures of solid lipids decreased in size and thickness in the mixtures containing OB at room temperature and slightly before the melting point, confirming previous characterizations. These results suggest that lipid mixtures with OB present a lower crystallinity, and it is expected that amorphous portion facilitates drug incorporation, for example.
Xavier, 2005; Dias, 2010; among others). The results achieved were the creation of WebQuests; the development of a deep reflection on the importance of the pedagogical use of technology in language teaching and the improvement of students' digital literacy.
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