Multiple Response Optimization of Beeswax-Based Nanostructured Lipid Carriers for the Controlled Release of Vitamin E

Consumer demand for cosmetics is growing, causing a need to develop new systems to release active ingredients. Among these, nanostructured lipid carriers (NLCs) have certain advantages regarding penetration of active compounds in the skin. The study reported here aimed to develop an NLC system for controlled release of vitamin E, a substance that has antioxidant and photoprotective properties. The NLCs containing vitamin E (NLC-VE) were prepared by the melting-emulsionsolidification method, using beeswax as the solid lipid, medium-chain triglycerides (MCTs), coconut oil or avocado oil as liquid lipids and three different nonionic surfactants. The composition of the system was defined by studying the effect of various experimental factors on the size distribution, average diameter and physical stability of the nanoparticles. The optimization of these characteristics, achieved by a Box-Behnken statistical design, showed that 8% w/w of the nonionic surfactant Tween 80, 24% ultrasound amplitude and processing time of 2 minutes and 16 seconds generated nanoparticles with homogeneous size (PDI = 0.11±0.02), average diameter of 180±20 nm and physical stability of 12 weeks. The NLC-VE systems prepared under the optimal conditions, containing Tween 80, beeswax and MCTs, were formulated as viscous suspensions by adding Pluronic F-127, a poly(ethylene oxide)-poly(propylene oxide) block copolymer, at a concentration of 10% w/w. The colloidal nanosuspension obtained had a viscosity of 222 mPa·s and released 70% of the active substance in 6 hours, indicating it is a promising candidate for controlled release of vitamin E.