Topical distribution and efficiency of nanostructured lipid carriers on a 3D reconstructed human epidermis model

This study evaluates the topical distribution and efficacy of nanostructured lipid carriers following administration on a 3D model of reconstructed human epidermis. These lipid nanocarriers were formulated with sunflower oil and loaded with retinyl palmitate and α-tocopherol, which are commonly used in cosmetics. The fluorescent dye DiO was incorporated with α-tocopherol to qualitatively characterize release during absorption studies. Physicochemical properties were investigated for nanostructured lipid carriers loaded with retinyl palmitate, with α-tocopherol labeled with DiO and for these empty nanocarrier systems. All characterized formulations demonstrated appropriate particle sizes for topical administration (≈200 nm), good electrostatic stability (between −48 and −80mV) and melting temperatures. Permeation profiles of retinyl palmitate and α-tocopherol, showed a controlled release with cumulative amounts of 270.5 ± 102.7 μg and 103.7 ± 50.6 μg, respectively after 24 h. The distribution of lipid nanoparticles loaded with α-tocopherol labeled with DiO was primarily in the stratum corneum layers. In vitro skin irritation testing on the human epidermis model was also performed and demonstrated that the nanostructured lipid carriers used here were non-irritants. These formulations are proven to be a suitable delivery system within our in vitro model and thus show great potential for incorporation in cosmetic formulations.