Combination of liquid crystalline systems and TiO₂-based nanoparticles for sun protection and drug delivery

Full text: The skin cancer is very common in countries that receive a high incidence of ultraviolet (UV) radiation. The sunscreen is one of the most utilized preventive measures against skin cancer. TiO₂ is an inorganic compound used as sunscreen in cosmetic/pharmaceutical formulations, it can reflect, absorb and/or scatter the UV radiation and its activity depends on the particle size. Nowadays, there is a high demand for multifunctional products and the use of liquid crystal (LC) has been increased because it promotes controlled delivery of actives. We prepared transparent TiO₂ based nanoparticles in temperature between 20 and 60°C and further incorporated in LC formulations and associated with antioxidant actives for controlled release. The propose of this work is to develop liquid crystalline multifunctional systems with transparent TiO₂ nanoparticles for skin photoprotection and controlled release of molecules with antioxidant activity to prevent and/or treat the skin diseases. In order to obtain LC, surfactants (PPG-5 ceteth 20 (P) and Polyoxyethylene (20) sorbitan monooleate (T)), an oil phase (coconut oil - Cocos nucifera L.) and ultrapure water (UW) were stirred at pH between 5-7. The polarized light micrographies associated to small angle X-ray scattering (SAXS) curves showed the presence of hexagonal, lamellar and cubic liquid crystalline phases and also micellar systems depending on synthesis conditions, with and without TiO₂ incorporated, confirming the possibility of the formation of different phases. We can conclude that these nanoparticles can be interesting on their application in organized systems, such as LC, due to use for controlled release of some antioxidant actives and protect the skin from UVA and UVB radiations and therefore be a promising multifunctional system. (author)