Skin cell targeting with self-assembled ligand addressed nanoemulsion droplets.

Dermo-pharmacy and cosmetic industries have utilized nanotechnologies for two decades. Initially proposed as vector systems for encapsulation of actives, they gained interest in increasing cutaneous bioavailability. Here, we assay the benefits of self-assembled nanoemulsions bearing ligands for targeting specific skin cells. Nanoemulsions, small droplets ranging typically from 20 nm to 150 nm, possess key properties for further use in cosmetics: long-term stability, optical transparency, extended range of textures and versatility. We investigated this nanoemulsion system and show ability to encapsulate a range of cosmetic actives with various physicochemical properties. Furthermore, this nanoemulsion presents a low cytotoxicity and is capable of directly targeting skin cells through simple addition of specific ligand in a one-step production protocol. This is of interest for increasing bioavailability of actives encapsulated into nanoemulsion droplets which may have penetrated the skin barrier to specific skin cell. Taken together, these chemical and in vitro observations suggest follow-up with in vivo models.

Simultaneous characterization of oxygen transport into and through porcine skin exposed to oxygen-saturated water.

Oxygen delivery to the skin is a promising approach for treatment of dermatological diseases (e.g. ischemic wound healing). However, characterization of oxygen transport into and through the skin exposed to oxygen carrier formulations has not been reported. In the present study, we developed an original lab-made static diffusion cell mounted with porcine skin enabling the assessment of oxygen uptake into the skin (i.e., oxygen penetration) and passage through the skin (i.e., oxygen permeation). Oxygen penetration and permeation were recorded by using an optical probe implanted into the skin tissue and a Clark-type electrode plunged into the receptor solution of the diffusion cells. Permeability parameters (i.e., maximal and steady-state flux; permeability coefficient) of oxygen were determined after a 2-hour application of oxygen-saturated water to either the skin surface (exogenous delivery) or the dermis (endogenous delivery). Similar experiments were performed by using intact or stripped skin in order to appreciate the role of the stratum corneum as oxygen barrier. Exogenous delivery of oxygen to skin tissue was found more effective than endogenous delivery through intact and stripped skin. However, exogenous oxygen permeation was found smaller than that determined from endogenous delivery. The upper layers of the skin would constitute a potential oxygen reservoir created by the high solubility of oxygen in epidermal lipids. Therefore, oxygen carrier formulations might significantly improve the oxygen status in the skin for further biological effects.