title: Nanoemulsions containing octyl methoxycinnamate and solid particles of TiO₂: preparation, characterization and in vitro evaluation of the solar protection factor.
abstract: The objective of this work was to develop and evaluate the physical-chemical properties of oil-in-water nanoemulsions for application as nanocosmetics for sun protection. Oil-in-water dispersions were processed by ultrasound (US) to obtain small emulsion droplets. These emulsions were obtained in the presence of commercial nonionic surfactants based on polyoxides and avocado oil as the oil phase. The US generated small but unstable droplets. This problem was solved by using a different surfactant, with a longer ethylene oxide chain, able to promote stabilization by steric mechanisms. The light scattering technique was used to characterize the nanoemulsions by their dispersed droplets' size, size distribution and variation of distribution with time (stability). Chemical and physical sunscreens - octyl methoxycinnamate (OMC) and titanium dioxide (TiO₂), respectively - were added to the stable system. The anti-UVB activity of the nanoemulsions and their components were evaluated by the method of Mansur et al. (1986) and spectral transmittance. The solar protection factor (SPF) was proportional to the OMC and TiO₂ concentrations. The in vitro OMC release was evaluated, and the presence of TiO₂ in the nanoemulsion did not affect the release profile, which showed the diffusion-dependent kinetics of the active ingredient in the formulation.
authors.affiliation: Instituto de Macromoléculas Professora Eloisa Mano, Universidade Federal do Rio de Janeiro (IMA/UFRJ), Centro de Tecnologia, Bl. J, Avenida Horácio Macedo, 2030, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, Brazil.
authors.forename: Flavia F F
authors.initials: FF
authors.lastname: Silva
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ricci-Júnior
authors.forename: Claudia R E
authors.initials: CR
authors.lastname: Mansur
mesh_terms: D055598:Chemical Phenomena; D002934:Cinnamates / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding; D004355:Drug Stability; D004655:Emulsions; D005638:Fruit / Q000737:chemistry; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D027421:Persea / Q000737:chemistry; D010592:Pharmaceutic Aids / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D059405:Sun Protection Factor; D013473:Sunscreening Agents / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry; D014025:Titanium / Q000737:chemistry*; D014465:Ultrasonics / Q000379:methods; D014783:Viscosity
chemical_list: D002934:Cinnamates; D004337:Drug Carriers; D004655:Emulsions; D010592:Pharmaceutic Aids; D010938:Plant Oils; D013473:Sunscreening Agents; D013501:Surface-Active Agents; C009495:titanium dioxide; C118580:octylmethoxycinnamate; D014025:Titanium