Читать книгу pH of the Skin: Issues and Challenges - Группа авторов - Страница 74

We wanted to devise an experiment to determine the pH of skin under a protective emollient layer. In other words, we wanted to answer the question “What is the skin pH under the emollient layer?” This provided technical challenges, since commercial pH electrodes are not designed to penetrate skin and an in vitro experiment would require a large effort and expense. However, we designed an alternative experimental approach using a skin analog. This emollient allowed us to answer the question in a fairly direct and cost-effective manner. We chose to mimic the skin using a collagen film (Coffi brand, 25 μm; Naturin Viscofan, Weinheim, Germany). Collagen is a major component of skin tissue and has been used as a skin substitute in other experiments. We know that the collagen is semi-permeable like skin and with the collagen skin-mimic film we could measure the surface pH on the top side or bottom side using a conventional pH electrode designed for skin. Collagen skin-mimic film was placed on top of an open vial filled with the pH buffer 10 solution. Emollient was applied beforehand to one side of the collagen skin-mimic film. The side of the collagen skin-mimic film with the emollient was placed in contact with the buffer pH 10 solution. A wet pH electrode was placed in contact with the opposite side of the collagen skin-mimic film from above (Fig. 9). This indirectly answers whether the pH under the emollient skin would change. The pH of the collagen skin-mimic film surface at the electrode was monitored as a function of time.