Shea butter solid nanoparticles for curcumin encapsulation: Influence of nanoparticles size on drug loading

In the present work, shea butter solid lipid nanoparticles (SLN) were prepared by sonication using nonionic surfactants as stabilizers without organic solvent. The mixture design methodology enabled to control particles size from 50nm to more than 1m according to the mixture composition. Then, curcumin, a natural polyphenol, has been encapsulated in nanoparticles with a wide range of diameters (50-230nm) and the encapsulation efficiency has been related to the particles sizes. The bigger the nanoparticles, the lower the encapsulation efficiency. The lipid structure at non dispersed state and under SLN form has been studied by differential scanning calorimetry and X-ray diffraction. From the obtained results, encapsulated curcumin did not affect the lipid properties at the SLN state unlike at non dispersed state. The localization of the curcumin in the outer shell of the lipid nanoparticles explained the evolution of the encapsulation efficiency according to the nanoparticles size. Practical applications: Solid lipid nanoparticles (SLN) can be used for the delivery of both hydrophobic and hydrophilic drugs. Preparing such nanovectors with natural, non-expensive materials and easily available (i.e., shea butter) will promote their potential use in several applications like oral, parenteral, dermal or ocular delivery. Controlling the particles size from the formulation composition and also the drug loading from SLN properties is of main importance to optimize the use of SLN as colloidal carrier.