Development of hybrid vesicular nanosystems composed of lipids and chitosan for octyl methoxycinnamate encapsulation

Nanotechnology is of great importance for the development of new medicines and cosmetic formulations. When applied to cosmetics, nanocarrier systems can prevent skin irritation, and in the case of sunscreens they can enhance photoprotection by improving photostability. Liposomes are considered a promising alternative for carrying different active ingredients, with the advantages of biocompatibility and low toxicity. However, they have low stability, which can cause leakage of the encapsulated substances, making it necessary to find ways to overcome this limitation. In this work, liposomes coated with the cationic polymer chitosan were developed to encapsulate octyl methoxycinnamate, a UVB sunscreen, to obtain systems with good stability and potential for application in photoprotective formulations. The systems were obtained from the incorporation of octyl methoxycinnamate (OMC) in a commercial pre-dispersion of lipids (Phosal (R) 53 MCT) and polysorbate 80 (Tween (R) 80), in which the best proportions of lipid and surfactant for encapsulation of OMC was established by evaluating the average size distribution, polydispersity index (PDI) and stability of the liposomes over time, using the dynamic light scattering (DLS) technique. We obtained a liposomal system with good stability (S1T1), with a size distribution profile with predominant populations around 110 and 510 nm and average PDI of 0.39. The S1T1 system was coated with low molecular weight chitosan, and the coated and uncoated structures (S1T1-Q and S1T1), respectively, were also evaluated by zeta potential (ZP) measurement, atomic force microscopy (AFM) and transmission electron microscopy (TEM) to ascertain the effect of the coating. The sun protection factor (SPF) was determined and in vitro release and in vitro cytotoxicity assays were performed for formulations containing S1T1 and S1T1-Q. The results demonstrated that the formulations containing the coated liposomes were efficient and suitable for topical application, in addition to presenting good stability and better release profile.