Crystallographic investigation of cetylpalmitate solid lipid nanoparticles

Solid lipid nanoparticles (SLN) as alternative intravenous colloidal drug carriers were produced by high pressure homogenisation of the melted lipid cetylpalmitate. The crystallographic properties of the used cetylpalmitate SLN were characterised by small angle X-ray scattering (SAXS) and X-ray diffraction (XRD). It was found that the SLN are available exclusively in a crystalline form. Different cetylpalmitate formulations showed all the same patterns and a uniform crystal lattice was obtained. A partial indexing of the signals of the cetylpalmitate was carried out and the unit cell of the cetylpalmitate was estimated by the Miller indices. A preferred orientation in 001-direction was observed. This can be explained by an impressive lamellar lattice structure of the cetylpalmitate. The results were compared with the crystal data of cetylpalmitate known from literature. There was no correlation with the monoclinic structure known so far. This could indicate that the SLN consist of crystallites of another modification of the cetylpalmitate.