Department of Physics, Stanford University, Stanford, CA, USA.
Department of Chemistry, University of California at Berkeley, Berkeley, CA, USA.
Nat Nanotechnol. 2019 May;14(5):420-425. doi: 10.1038/s41565-019-0395-0. Epub 2019 Mar 4.
Electron microscopy has been instrumental in our understanding of complex biological systems. Although electron microscopy reveals cellular morphology with nanoscale resolution, it does not provide information on the location of different types of proteins. An electron-microscopy-based bioimaging technology capable of localizing individual proteins and resolving protein-protein interactions with respect to cellular ultrastructure would provide important insights into the molecular biology of a cell. Here, we synthesize small lanthanide-doped nanoparticles and measure the absolute photon emission rate of individual nanoparticles resulting from a given electron excitation flux (cathodoluminescence). Our results suggest that the optimization of nanoparticle composition, synthesis protocols and electron imaging conditions can lead to sub-20-nm nanolabels that would enable high signal-to-noise localization of individual biomolecules within a cellular context. In ensemble measurements, these labels exhibit narrow spectra of nine distinct colours, so the imaging of biomolecules in a multicolour electron microscopy modality may be possible.
电子显微镜在我们理解复杂生物系统方面发挥了重要作用。虽然电子显微镜可以以纳米级分辨率揭示细胞形态，但它不能提供关于不同类型蛋白质位置的信息。一种基于电子显微镜的生物成像技术，如果能够对单个蛋白质进行定位，并解析相对于细胞超微结构的蛋白质-蛋白质相互作用，将为细胞的分子生物学提供重要的见解。在这里，我们合成了小的镧系掺杂纳米粒子，并测量了单个纳米粒子在给定的电子激发通量（阴极发光）下的绝对光子发射率。我们的结果表明，优化纳米粒子的组成、合成方案和电子成像条件，可以得到亚 20nm 的纳米标记，从而可以在细胞环境中实现单个生物分子的高信噪比定位。在集合测量中，这些标记表现出九条不同颜色的窄光谱，因此在多色电子显微镜模式下对生物分子进行成像可能是可行的。
