2.3. Preparation of NLC Formulations

Different formulations were prepared using the hot emulsification–ultrasonication method. The lipid phases of the formulations consisted of various natural lipids (Table 1). All lipid phases were heated in a water bath 10 °C above the melting temperature of each solid lipid (Cocoa butter—45 °C; beeswax—64 °C; Murumuru butter—47 °C). The aqueous phase, which was the same for all formulations, was composed of a poloxamer solution (5% w/v, Sigma Aldrich^®, St. Louis, MO, USA) that was heated to the lipid phase at the same temperature. For pre-emulsion formation, the aqueous phase was added dropwise to each lipid phase while stirring at 10,000 rpm for 2 min in an Ultra-Turrax homogenizer (Ultra-Turrax^® T18, Berlin, Germany). The resulting pre-emulsions were immediately sonicated for 15 min. Next, the formed nanoemulsions were cooled in an ice bath until reaching 25 °C to solidify the formed nanoparticles [18].

Composition of nanostructured lipid carriers.