Impact of hydrophilic natural deep eutectic solvents on hydrogels intended for skin application
Résumé
NaDES were identified recently as interesting green solvent to prepare cosmetic ingredients from biomasses. Betaine/glycerol and glucose/glycerol were shown to be of particular interest in the extraction and stabilization of phycoproteins. The aim of this investigation was to evaluate the impact of the incorporation of these well-known NaDES in a cosmetic gel intended for skin application. Betaine/glycerol (BG) and glucose/glycerol (GG) were incorporated at 3 different concentrations (1%, 5% and 10%) in two different hydrogels based on a hemisynthetic cellulose derivative and a vegetable gum respectively. The organoleptic and physico-chemical characteristics of the NaDES-enriched gels were observed over 30 days at room temperature (25°C) and in accelerated aging conditions (40°C, 75°C humidity). Obtained results showed notably that the incorporation of NaDES does not change significantly the pH of the formulations, but has a variable impact on the viscosity of the gels depending on the composition of the NaDES, their concentration and the method of incorporation. These results highlight the importance of understanding the interaction of NaDES with the ingredients of the formula for a predictive approach of their compatibility as ingredients in cosmetic formulations.