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 (Γ_s) of emulsifiers, were tuned by controlling the type/concentration of emulsifier used to prepare the SLNs. Increasing the Γ_s decreased the contact angle at the oil–water interface, which enhanced the displacement free energy of the SLNs at the interface. Moreover, the Γ_s of emulsifiers bound to the surface of SLNs covering oil droplets was linearly correlated with the SLN-own Γ_s. 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.