Transepidermal water loss is one of the main properties of the skin indicative of its barrier function. Careful skin care with properly selected cosmetic products is crucial for maintaining an optimal level of moisture in the skin and, to maintain its protective role. Hydrogels, carrier systems with a wide range of applications, are often used for this purpose and play an important role in the fields of medicine, pharmacy, biotechnology and cosmetology.
As part of the thesis work, two sets of hydrogels were evaluated on porcine skin in vitro. The first set consisted of hydrogels based on nanocrystalline cellulose, a type of nanomaterial derived from cellulose, and the second set consisted of hydrogels for facial cleansing with whey, a by-product of cheese production. We were interested in their impact on the skin's barrier function, specifically on transepidermal water loss. The first set of hydrogels based on nanocrystalline cellulose consisted of four formulations with different qualitative and quantitative compositions, namely, a natural polymer (aginate or pectin), a variable proportion of water and one of two types of nanocrystalline cellulose. During the evaluation, we observed that the final TEWL values of all four formulations were comparable, and the obtained results did not unequivocally confirm the positive effects of hydrogel application in reducing TEWL values. In addition, we also dried these hydrogels to form films and examined their influence on TEWL values. With the obtained results, we confirmed that the use of films is beneficial, which is further supported by TEWL values that remained comparable to the basal values for all parallels. In the continuation of the study, we focused on facial cleansing formulations with whey, developed in previous studies. We wanted to evaluate their potential for irritation based on the different concentration of the incorporated surfactant. We found that the incorporated surfactant did not have a negative impact on the skin's barrier function. Therefore, the developed hydrogels for facial cleansing are suitable for the use on even more sensitive skin. With the results of this thesis, we confirmed the importance of in vitro evaluation of hydrogels before their application on the skin. The results of the TEWL evaluation are therefore essential for the development of moisturizing and non-irritating hydrogels for skin application.
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