Solid lipid nanoparticle (SLN) formulations as a potential tool for the reduction of cytotoxicity of saponins

The present pilot study explored the potential of solid lipid nanoparticles (SLN) to entrap saponins and reduce the membrane toxicity of these compounds. SLN composed of different types of solid lipid were prepared by the cold homogenisation technique. Combinations of anionic, cationic and non-ionic stabilisers were selected in order to obtain negatively, positively and neutrally charged SLN. Mean particle size and zeta potential of blank and saponin-loaded formulations were measured by Dynamic Light Scattering (DLS), Electrophoretic Light Scattering (ELS) and in vitro cytotoxicity on MRC-5 SV2 and J774 cells was assessed using a resazurin-based assay. The type of solid lipid used for the formulation influenced the mean particle size, while the zeta potential mainly depended on the kind of surfactant utilised. Blank SLN composed of hard fat and anionic or non-ionic surfactants did not result in cytotoxicity. After loading with saponin, the anionic hard fat SLN was found to be the optimal formulation.