Development of a New Process for the Manufacture of Nanostructured Particles for UV Filter Encapsulation

This study describes a successful process using high pressure homogenization (HPH) and interfacial polymerization to produce nanoencapsulation of a UV-filter. Actually, this kind of agent has some limitations mainly related to photostability, degradation and toxicity, and then the process of encapsulation promises to overcome these drawbacks by protecting the active substance. Octyl-methoxycinnamate (OMC) was used as UV-filter model to develop the nanostructured particles. The nanocapsules were prepared by emulsification (using HPH) of an organic phase containing 4,4'-methylene-diphenyl-di-isocyanate (MDI) (a hydrophobic monomer), medium-chain triglycerides, Span 80 and OMC, in an aqueous solution composed of sodium lignosulfonate (stabilizing agent), Pluronic F127 and ethylene glycol (a hydrophilic monomer). In sequence, the polymerization of MDI and ethylene glycol at the water-oil droplet interface was performed at 40 ° C during 4 hours. The nanocapsules dispersions were characterized with respect to their particle size (DLS), zeta potential (electrophoretic mobility), morphology (SEM-FEG), efficiency for UV absorption (UV spectrometry) and FTIR. The nanostructured particles developed here have diameter in a nanometric scale (between 251 and 661 nm), very low polydispersity index (around 0.1 to 0.3), negative zeta potential (about -46,0 mV), fluid aspect and colloidal stability during more than 2 months. The nanocapsules dispersion in a 0.005% (w/w) concentration absorbed around 70% of UV light incident, demonstrating the increase of UV-filter efficacy. In conclusion, the HPH and interfacial polymerization processes allowed producing nanostructured particles to encapsulate UV-filters, presenting a promising system to protect against UV radiation.