Effect of beeswax modification on the lipid matrix and solid lipid nanoparticle crystallinity

The influence of a heterolipid (Phospholipon 90G®, P90G), which directly modifies the surface of solid lipid nanoparticles (SLN), and goat fat on the crystallinity of beeswax matrix and the SLN prepared therefrom was studied. Lipid matrices composed of 30% (w/w) of P90G in beeswax and in 1:1 mixture of beeswax and goat fat were formulated and characterized. SLN containing polysorbate 80 with or without P90G were formulated by hot high-pressure homogenisation and characterized by particle size and zeta potential measurements. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) patterns of the SLN were compared with the lipid matrices. Results showed WAXD of the lipid matrices containing P90G contain amorphous portions. Most SLN formulated possessed low z-average diameters and polydispersity indices, which remained constant after 3 months, with high-negative potentials after 4 weeks and crystallized into stable modification within 48 h of preparation. The overall result indicated that P90G and goat fat influenced the crystallinity of beeswax matrix and its SLN, but the crystallinity of the mixed lipid matrix (1:1 beeswax/goat fat) and its SLN, beeswax containing P90G and its SLN was lower than that of beeswax alone and its SLN. There was no increase in crystallinity of SLN on storage. Modification of beeswax with P90G or goat fat offers a way of improving the SLN formulated with beeswax in terms of reduction of its crystallinity responsible for its low-drug incorporation efficiency.