Sousa A A, Hohmann-Marriott M, Aronova M A, Zhang G, Leapman R D
Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Building 13, Room 3N17, 13 South Drive, Bethesda, MD 20892, USA.
J Struct Biol. 2008 Apr;162(1):14-28. doi: 10.1016/j.jsb.2008.01.007. Epub 2008 Jan 26.
It is shown that dark-field images collected in the scanning transmission electron microscope (STEM) at two different camera lengths yield quantitative distributions of both the heavy and light atoms in a stained biological specimen. Quantitative analysis of the paired STEM images requires knowledge of the elastic scattering cross sections, which are calculated from the NIST elastic scattering cross section database. The results reveal quantitative information about the distribution of fixative and stain within the biological matrix, and provide a basis for assessing detection limits for heavy-metal clusters used to label intracellular proteins. In sectioned cells that have been stained only with osmium tetroxide, we find an average of 1.2+/-0.1 Os atom per nm(3), corresponding to an atomic ratio of Os:C atoms of approximately 0.02, which indicates that small heavy atom clusters of Undecagold and Nanogold can be detected in lightly stained specimens.
结果表明，在扫描透射电子显微镜（STEM）中以两种不同相机长度采集的暗场图像，可得出经染色的生物样本中重原子和轻原子的定量分布。对配对的STEM图像进行定量分析需要了解弹性散射截面，该截面由美国国家标准与技术研究院（NIST）弹性散射截面数据库计算得出。结果揭示了关于固定剂和染色剂在生物基质中分布的定量信息，并为评估用于标记细胞内蛋白质的重金属簇的检测限提供了依据。在仅用四氧化锇染色的切片细胞中，我们发现每立方纳米平均有1.2±0.1个锇原子，对应锇与碳的原子比约为0.02，这表明在轻度染色的样本中可以检测到十一金和纳米金的小重原子簇。
