Wu Kenneth S, van Osdol William W, Dauskardt Reinhold H
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
Biomaterials. 2006 Feb;27(5):785-95. doi: 10.1016/j.biomaterials.2005.06.019. Epub 2005 Aug 10.
An in vitro mechanics approach to quantify the intercellular delamination energy and mechanical behavior of isolated human stratum corneum (SC) in a direction perpendicular to the skin surface is presented. The effects of temperature, hydration, and a chloroform-methanol treatment to remove intercellular lipids were explored. The delamination energy for debonding of cells within the SC layer was found to be sensitive to the moisture content of the tissue and to the test temperature. Delamination energies for untreated stratum corneum were measured in the range of 1-8J/m(2) depending on test temperature. Fully hydrated specimen energies decreased with increasing temperature, while room-humidity-hydrated specimens exhibited more constant values of 2-4J/m(2). Lipid-extracted specimens exhibited higher delamination energies of approximately 12J/m(2), with values decreasing to approximately 4J/m(2) with increasing test temperature. The peak separation stress decreased with increasing temperature and hydration, but lipid-extracted specimens exhibited higher peak stresses than untreated controls. The delaminated surfaces revealed an intercellular failure path with no evidence of tearing or fracture of cells. The highly anisotropic mechanical behavior of the SC is discussed in relation to the underlying SC structure.
本文提出了一种体外力学方法，用于量化分离的人体角质层（SC）在垂直于皮肤表面方向上的细胞间分层能量和力学行为。研究了温度、水合作用以及用氯仿 - 甲醇处理去除细胞间脂质的影响。发现角质层内细胞脱粘的分层能量对组织的水分含量和测试温度敏感。根据测试温度，未处理角质层的分层能量在1 - 8J/m²范围内测量。完全水合的标本能量随温度升高而降低，而室温湿度水合的标本表现出更恒定的值，为2 - 4J/m²。脂质提取的标本表现出约12J/m²的较高分层能量，随着测试温度升高，值降至约4J/m²。峰值分离应力随温度和水合作用增加而降低，但脂质提取的标本比未处理的对照表现出更高的峰值应力。分层表面显示出细胞间失效路径，没有细胞撕裂或断裂的迹象。讨论了角质层高度各向异性的力学行为与潜在的角质层结构的关系。
