Silver-nanolipid complex for application to atopic dermatitis skin: rheological characterization, in vivo efficiency and theory of action.

A skin care formulation was developed by incorporating microsilver, in combination with nanostructured lipid carriers (NLC) into an o/w cream and lotion. To increase skin adhesion of the NLC, and subsequent film formation and occlusion onto the skin, the NLC were produced with a size of about 200 nm. Production of NLC was performed by high-pressure homogenisation. Characterization was performed regarding size and charge (zeta potential), and for the cream and lotion also by rheology. Incorporation of NLC and/or microsilver into the cream or lotion led to pronounced changes in the thixotropic behaviour (shape of rheogram, yield point, viscosity). This was explained by specific interaction of the nanoparticles and/or the microsilver with the two formulations. In vivo studies revealed a high potential to remove not only symptoms of irritated sensitive skin, but also of light to medium atopic dermatitis. Based on zeta potential measurements, a silver ion-nanolipid complex seems to form which leads to a higher activity of the antimicrobial silver, e.g., increasing the silver ion concentration on skin and bacterial membranes. The antimicrobial effect in combination with restoration of normal skin condition (repair of stratum corneum lipid film by NLC) is obviously sufficient to replace in many cases medical therapy with glucocorticoids by a biological, natural skin care cosmetic nano formulation.