Microemulsion-Based Solid Lipid Nanoparticles As Emulsion Stabilisers

The preparation and properties of water-in-oil (W/O) emulsions stabilised solely by adsorbed surface-active solid lipid nanoparticles (SLNs) at the oil-water interface were studied. Monostearin-based SLNs were prepared using food-grade micoremulsions as nanoscle 'reactors'. Hot oil-in-water (O/W) microemulsions (70°C) consisting of monostearin, Tween 20, ethanol and water were crash-cooled to 4°C to promote the liquid-solid transition of the monostearin and thus develop sub-micron solid lipid particles. SLNs obtained from the cooled microemulsions were partially stabilised with addition to lecithin (0.5% w/w) to the microemulsion system. With 2% (w/w) added monstearin, the W/O emulsion was stable for the 14 days of study. The microstructure of the emulsions revealed the presence of two stabilisation mechanisms, namely Pickering-type and continuous phase crystal network stabilisation, which both contributed to slowing dispersed droplet coalescence. Overall, this study demonstrated that surface-active SLNs developed using a microemulsion technique could effectively kinetically stabilise model W/O emulsions.