Chen Y L, Wiedmann T S
3M Life Sciences Sector Laboratory, Maplewood, Minnesota 55144, USA.
J Invest Dermatol. 1996 Jul;107(1):15-9. doi: 10.1111/1523-1747.ep12296521.
The cohesive strength of the stratum corneum is determined by its unique molecular composition and structural architecture. Whereas the structure responsible for corneocyte cohesion has been visualized at the microscopic level, the structure of the intercellular domain has not been characterized at the molecular level. In this report, new insight into the molecular architecture of the stratum corneum has been provided by atomic force microscopy and x-ray photoelectron spectroscopy. The surface layer of human stratum corneum was stripped, yielding the characteristic polygonal corneocytes shown by scanning electron microscopy as well as low resolution atomic force microscopy. With atomic force microscopy, the resolution was increased to allow imaging of the molecular architecture of the stratum corneum. With the high resolution image, a repetitive pattern characteristic of lipids in an ordered state was visualized. The lattice appeared to be orthorhombic where the lattice distances were about 5.5 and 9 angstroms, and the lattice angle was close to 90 degrees. The atomic composition of the superficial layers was 82% carbon, 16.5% oxygen, and 1.4% nitrogen as determined by x-ray photoelectron spectroscopy. The high nitrogen content compared to the calculated stratum corneum lipid composition and measured model lipid composition suggests that proteins were detected. In summary, although proteins are present, the fracture plane of the stratum corneum is largely composed of lipids that appear to have a distorted orthorhombic packing.
角质层的内聚强度由其独特的分子组成和结构架构决定。尽管负责角质形成细胞黏附的结构已在微观层面可视化，但细胞间区域的结构在分子层面尚未得到表征。在本报告中，原子力显微镜和X射线光电子能谱为角质层的分子架构提供了新的见解。人类角质层的表层被剥离，得到了扫描电子显微镜以及低分辨率原子力显微镜所显示的特征性多边形角质形成细胞。借助原子力显微镜，分辨率得以提高，从而能够对视角质层的分子架构进行成像。通过高分辨率图像，可以看到有序状态下脂质特有的重复图案。晶格似乎是正交晶系的，晶格间距约为5.5埃和9埃，晶格角接近90度。通过X射线光电子能谱测定，表层的原子组成为82%的碳、16.5%的氧和1.4%的氮。与计算出的角质层脂质组成和测量的模型脂质组成相比，高氮含量表明检测到了蛋白质。总之，尽管存在蛋白质，但角质层的断裂面主要由似乎具有扭曲正交堆积的脂质组成。
