Inorganic layered double hydroxides as a 4-hexyl resorcinol delivery system for topical applications

Abstract

In this study, the hydrophobic even skin tone active, 4-hexylresorcinol (HR), was intercalated into a zinc aluminium layered double hydroxide (ZnAl-LDH) by a co-precipitation method and used as a controlled release ingredient in skin care formulation. The resulting nanohybrid (LDH–HR) was characterized using different techniques: XRD, FTIR, TEM, SEM, and TGA. The intercalation reaction between HR and LDH was confirmed using XRD, and FTIR. Some extent of aggregation was observed for the LDH–HR nanoparticles from TEM and SEM results. The thermal behaviour of HR drastically improved after intercalation into the LDH host. Strong electrostatic interactions between the HR and ZnAl-LDH galleries in the nanohybrid and the sustained release of HR from the LDH–HR in phosphate buffered saline (PBS) were observed. We also investigated the de-pigmenting efficiency of the LDH–HR nanohybrid containing formulations in randomized controlled experiments, which showed impressive results after 14 days of topical applications. The LDH–HR nanohybrid significantly minimized the melanogenesis in primary human melanocytes, resulting in overall improvements in even skin tone. Based on the above results, we believe that the LDH–HR nanohybrid has high potential for use as an alternative active ingredient in topical applications for uneven skin tone.