Interfacial and colloidal characterization of oil-in-water emulsions stabilized by interface-tunable solid lipid nanoparticles.

We evaluated the correlation between the interfacial characteristics of solid lipid nanoparticles (SLNs) and the interfacial/colloidal stability of SLN-stabilized emulsions. Herein, the interfacial properties of SLNs, particularly the surface load (Γs) of emulsifiers, were tuned by controlling the type/concentration of emulsifier used to prepare the SLNs. Increasing the Γs decreased the contact angle at the oil-water interface, which enhanced the displacement free energy of the SLNs at the interface. Moreover, the Γs of emulsifiers bound to the surface of SLNs covering oil droplets was linearly correlated with the SLN-own Γs. The size/ζ-potential of emulsions stabilized by SLNs covered by the highest concentration of emulsifiers was unchanged for 1 month, indicating good emulsion stability. The interfacial/colloidal stability of SLN-stabilized emulsions was thus enhanced by increasing the emulsifier concentration used to produce the SLNs. This study provides baseline data for developing SLN-stabilized emulsions for the food, cosmetic, and pharmaceutical industries.