O/W/O multiple emulsions containing soluble collagen: in vitro and in vivo skin biophysical properties evaluation

Abstract

The integrity of the stratum corneum is essential for skin hydration. In order to fulfill all of its functions, a balance of the water content in the stratum corneum is necessary, as well as maintaining the epidermis, an essential objective of cosmetic formulations. Cosmetic skin hydration can be achieved through the frequent application of cosmetic products that can act through basic mechanisms: occlusion, moisturization, and hydration or active moisturization. Therefore, when developing new cosmetic products, it is important to consider their positive effect on skin hydration and viscoelasticity, considering that the objective of a cosmetic product is to protect the skin and delay skin aging. Subsequently, multiple O/W/O emulsions were developed and skin hydration was evaluated in vitro and in vivo. The in vitro method for skin hydration employs gelatin whose composition mimics collagen and NMF of the skin, forming a surface (1 cm thick) through which internal water vapor can be released. The occlusion provided to this gelatin surface is evaluated, and the hydrating power of the applied products is determined. Due to the composition of the gelatin support cell and the evaporation of water inside it, it can simulate TEWL of the skin. The in vivo evaluation of hydration, pH, and sebum of the aqueous solution of proteins, simple O/W, and multiple O/W/O with collagen showed that O/W/O emulsions provided greater occlusive and oily content, maintaining the pH levels of the skin. Therefore, these O/W/O systems improve conditions for dry skin.

Graphical abstract

Scheme of the gelatin support cells before (A) and after (B) the application of the O/W_Co/O multiple emulsions.

Keywords:

• Multiple emulsions
• O/W/O
• collagen
• in vitro and in vivo skin evaluation

Author contributions

Conceptualization, methodology, writing - review and editing P.A.R.F., methodology, practical execution M.M. Both authors have read and agreed to the published version of the manuscript.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

This research received no external funding