Application of moisturizing face masks is important, because it helps us keep a healthy skin barrier. Skin barrier is important for protecting our underlying tissue from externel factors (UV radiation, microorganisms, chemicals) and keeping skin cycles in balance. Many studies research different types of nanocellulose and their purpose in cosmetic products. It is most often found in skin care products such as creams, lotions, masks and gels, because of it's good rheological properties and high water retention capacity.
We formulated facial masks based on NCC hydrogels, in which ethanol and/or water were entrapped as the liquid phase. The formulations differed in the type of added polymer, the addition of electrolytes and humectants and the proportion of nanocrystalline cellulose (NCC). We developed masks with added ethanol that contained polymer pullulan, hyaluronic acid and NCC in different mass fractions (6, 8, or 10%). In the remaining NCC mask formulations, we incorporated only water as the entrapped liquid phase. These differed in addition of the polymer (Na-alginate), the electrolyte CaCl2, the mass fraction of NCC or they contained only 10% and 12% NCC in addition to water. Then, the rheological properties of five selected masks that maintained physical stability for a longer period of time, were measured with a rheometer at 32°C. We continued the research by applying masks to the skin, where we tested the effect of each mask on the parameters of transepidermal water loss (TEWL) and skin hydration. We found that masks containing ethanol significantly worsen both parameters, which we linked to its drying effect. Therefore, we further evaluated only the mask with 12% NCC. The study was conducted on five volunteers, three of whom had previously applied 90% ethanol to their skin (disruption of the skin barrier). We noticed worsening of TEWL parameter after applying the mask in all volunteers and worsening of hydration after applying the mask in those, with a previous application of 90% ethanol. We concluded, that higher TEWL value after applying the NCC mask in all volunteers is a consequence of increased skin barrier permeability. Thus, even after removing the face mask, it is advisable to continue facial care with application of moisturizing and/or occlusive cosmetic product.
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