Characterization and evaluation of poly(epsilon-caprolactone) nanoparticles containing 2-ethylhexyl-p-methoxycinnamate, octocrylene, and benzophenone-3 in anti-solar preparations.

Ultraviolet radiation can bring both harm and benefits to human health. Among those harms are erythemas, photosensitivity, photoaging, and the most worrying, skin cancer. Nanoencapsulation of sunscreen agents (SA) by using a biocompatible and biodegradable polymer such as poly(epsilon-caprolactone) (PCL) is advantageous as it increases the retention of UV absorbers in the skin, avoids systemic absorption, and consequently, improves water resistance and stability of the preparation. The aim of this work is to develop, characterize, and study the encapsulation of 3 different SA: 2-ethylhexyl-p-methoxycinnamate, benzophenone-3, and octocrylene in PCL nanoparticles (Nps). Nps were prepared by the solvent emulsification and evaporation method. The process yield was calculated, and the Nps were characterized in terms of size, polydispersity index (PI), morphology, zeta potential (ZP), encapsulation efficiency (EE) (%), and sunscreen agent content (SAC). The final formulations were submitted to the hen's egg test-chorioallantoic membrane (HET-CAM), chorioallantoic membrane-trypan blue staining (CAM-TBS), red blood cell (RBC), Draize tests, in vitro release, in vitro sun protection factor (SPF), UVA protection factor (PF-UVA), and photostability. All the Nps were in the nanometric scale. PI showed monodisperse systems. ZP became more negative as the Np were lyophilized and were added to the formulations. EE varied from 84 to 90%. The SAC went from 44 to 65 microg of sunscreen agents by milligram of Np. The process yield went from 60 to 76%. Nps were predominantly spherical and elliptical forms. The addition of Np diminished the release of the SA. The SPF increased with Np presence and helped to maintain the PF-UVA after irradiation. The HET-CAM assay evaluated the formulation as slightly irritant, CAM-TBS and RBC tests as non irritant, and the Draize test as moderately irritant.