보습제의 종류와 pH에 따른 피부 각질층의 팽윤 및레올로지 특성에 관한 연구
Study on Swelling and Rheological Properties of the Stratum Corneum under Various Moisturizers and pH Conditions
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Skin is the largest organ of the body as determined by its wet weight or by its surface area. The swelling and rheological properties are very important factor in human dermatology. It is known that a relationship exists between the swelling and rheological property. Female pig skin 45~50 g were kept under conventional laboratory conditions. Dorsal hairs, over an 2 area of approximately 8 cm2, were shaved with electric clipper 1 day prior to the experiment. Crude sample of pig Stratum Corneum (SC) was prepared with 0.1 M tris buffer pH 7.2 (2 M urea, 0.5% trypsin) solution (78 hr) at 37℃. The sample was further purified from n-hexane during 5 hr. The sample pieces (1.5 mm×15 mm) of pig SC were weighted and immersed in the appropriate test solution and reweighed after the immersion to estimate the extent of swelling of the sample in each pH controlled solutions. Moisture contents for pig SC were measured under various humidity conditions. The mechanical properties of pig SC were also estimated by rheometer. The results showed the acidic pH solution gives the pig SC its toughness, an important mechanical property primarily attributable to the intra- and intermolecular interactions of keratin molecules. At pH 3~5, keratin molecules were considered to be oppositely charged and electrostatically bound to each other. Above pH 7, the swelling of pig SC was ascribed to the deionization of the amino groups, which would break the electrostatic linkage between the two functional groups and make the protein chains negatively charged. However, to clarify the swelling and rheological mechanism of the human SC, further study is needed with quantitative investigation on the charge density of the keratin molecule and the distribution of ionic species between keratin molecule and the ambient solution.
Abstract
Skin is the largest organ of the body as determined by its wet weight or by its surface area. The swelling and rheological properties are very important factor in human dermatology. It is known that a relationship exists between the swelling and rheological property. Female pig skin 45~50 g were kept under conventional laboratory conditions. Dorsal hairs, over an 2 area of approximately 8 cm2, were shaved with electric clipper 1 day prior to the experiment. Crude sample of pig Stratum Corneum (SC) was prepared with 0.1 M tris buffer pH 7.2 (2 M urea, 0.5% trypsin) solution (78 hr) at 37℃. The sample was further purified from n-hexane during 5 hr. The sample pieces (1.5 mm×15 mm) of pig SC were weighted and immersed in the appropriate test solution and reweighed after the immersion to estimate the extent of swelling of the sample in each pH controlled solutions. Moisture contents for pig SC were measured under various humidity conditions. The mechanical properties of pig SC were also estimated by rheometer. The results showed the acidic pH solution gives the pig SC its toughness, an important mechanical property primarily attributable to the intra- and intermolecular interactions of keratin molecules. At pH 3~5, keratin molecules were considered to be oppositely charged and electrostatically bound to each other. Above pH 7, the swelling of pig SC was ascribed to the deionization of the amino groups, which would break the electrostatic linkage between the two functional groups and make the protein chains negatively charged. However, to clarify the swelling and rheological mechanism of the human SC, further study is needed with quantitative investigation on the charge density of the keratin molecule and the distribution of ionic species between keratin molecule and the ambient solution.
참고문헌 (17)
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