Scanned electron probes can be used to characterize soft as well as hard materials, and the interfaces between them in 3-D at the nanoscale. Here, we illustrate the application of scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS), electron tomography (ET), and serial block face scanning electron microscopy (SBF-SEM) to study bionanoparticles, cells and tissues. The use of focused probes offers important advantages for determining 3-D structure on scales ranging from tens of nanometers to micrometers since it is possible to optimize signals generated by the interactions between the incoming electrons and the specimen depending on the primary beam energy (1 keV to 300 keV). For example, STEM and EELS enable the characterization of structure and elemental composition in multicomponent hybrid nanocarriers with controlled architecture and chemical functionality that offer great potential for development of <i>in vivo</i> and <i>ex vivo</i> medical diagnostics and therapeutics. At larger scales, ET based on axial bright-field STEM imaging enables the determination of 3-D structure in micrometer-thick sections through cells; and the complementary approach of SBF-SEM is proving valuable for analyzing 3-D ultrastructure of cells and tissues over volumes extending up to one million cubic micrometers.

Imaging nanoparticles, cells and tissues in 3-D using focused electron probes

254th National Meeting (2017)

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