Current State of Lipid Nanoparticles (SLN and NLC) for Skin Applications.

The increasing knowledge on skin physiology, formulation science and nanotechnology has led to continuous improvements in cosmetics, and introduction of dermocosmetics has been increasing particularly for the management of skin disorders such as acne, eczema, psoriasis, etc. Nowadays, research has been focused on the development of products which can efficiently administer active compounds to the target skin layers while minimizing side effects. The use of multifunctional lipid nanoparticles for cosmetic and dermocosmetic purposes is promising not only because biocompatible ingredients are used in their composition, but also because of their ability to show enhanced skin penetration. Although the introduction of liposomes has been a hallmark of lipid nanoparticles, development of novel systems capable of encapsulating active compounds with tunable release profiles, that show good stability, are easy to manufacture and handle remains a necessity. Solid lipid nanoparticles (SLN) were introduced as alternative formulations for emulsions, liposomes and polymeric nanoparticles, whereas nanostructured lipid carriers (NLC) were developed later as second-generation nanoparticles. However, both SLN and NLC show many inherited advantageous properties to be used for dermal applications including ability to provide occlusion and photoprotective effect and skin hydration, and various SLN and NLC based products are already in the market. This review provides an overview on the current state-of-art of SLN and NLC particularly for cosmetic and dermocosmetic purposes, discuss their formulation composition, structures and preparation techniques. Their use for the topical delivery of active compounds in different skin disorders is highlighted along with examples of commercialized products.