Griffith O H, Habliston D L, Birrell G B, Skoczylas W P, Hedberg K K
Institute of Molecular Biology, University of Oregon, Eugene 97403.
Proc Natl Acad Sci U S A. 1989 Mar;86(6):1826-30. doi: 10.1073/pnas.86.6.1826.
Biological surfaces emit electrons when subjected to UV light. This emission is increased greatly after exposure to cesium vapor. Increases from 2 to 3 orders of magnitude are observed, depending on the biochemicals present. Heme and chlorophyll exhibit unusually high photoemission currents, which are increased further after cesiation. Photoemission from proteins and lipids is much less but also is increased by exposure to cesium. The formation of photocathodes with cesium greatly increases the practical magnifications attainable in photoelectron microscopy of organic and biological specimens. Photoelectron micrographs taken at magnifications greater than or equal to X 100,000 of chlorophyll-rich thylakoid membranes and of colloidal gold-labeled cytoskeleton preparations of cultured epithelial cells demonstrate the improvement in magnification. The selectivity and stability of the photocathodes suggest the possibility of detecting chromophore binding proteins in membranes and the design of photoelectron labels for tagging specific sites on biological surfaces.
生物表面在受到紫外线照射时会发射电子。暴露于铯蒸气后，这种发射会大大增加。根据存在的生化物质不同，可观察到增加幅度在2到3个数量级之间。血红素和叶绿素表现出异常高的光发射电流，在铯处理后会进一步增加。蛋白质和脂质的光发射要少得多，但暴露于铯也会使其增加。用铯形成光电阴极大大提高了在有机和生物标本的光电子显微镜中可实现的实际放大倍数。对富含叶绿素的类囊体膜以及培养上皮细胞的胶体金标记细胞骨架制剂在大于或等于X 100,000的放大倍数下拍摄的光电子显微照片证明了放大倍数的提高。光电阴极的选择性和稳定性表明有可能检测膜中的发色团结合蛋白，并设计用于标记生物表面特定部位的光电子标签。
