Recently developed EM-based tools for determining nanoscale biological ultrastructure
Abstract: Electron microscopy provides nanoscale information about the architecture and composition of biological structures ranging in size from isolated supramolecular assemblies, to organelles, cells, and tissues. To extract such information requires careful consideration of how the primary electrons are scattered both elastically and inelastically by the atoms in the sample. Some relatively new EM-based techniques include: (1) scanning transmission electron tomography, which enables the determination of three-dimensional ultrastructure in specimens that are considerably thicker than can be analyzed by conventional electron tomography; (2) electron energy-loss spectroscopic imaging and energy-filtered transmission electron microscopy, which allow identification of small numbers of specific atoms bound to biological structures; and (3) serial block face scanning electron microscopy, which provides nanoscale ultrastructure in tissue volumes that extend across a million cubic micrometers. These same tools also facilitate the characterization of exogenous nanostructures that have potential medical applications in diagnostic imaging and therapeutics. Advanced structural tools based on electron microscopy are becoming ever more important as researchers endeavor to understand how large macromolecules assemble into the highly complex architectures of cells and tissues.
Richard Leapman obtained B.A. and M.A. in Natural Sciences, and Ph.D. in physics from the University of Cambridge, UK. He then trained as a postdoctoral fellow in the Department of Materials at the University of Oxford, UK, and in the Department of Applied and Engineering Physics at Cornell University, NY, where he contributed to the development of electron spectroscopy for the nanoscale characterization of materials. He subsequently moved to NIH to develop methods based on scanning transmission electron microscopy and electron spectroscopy to determine the structure and chemical composition of cells and supramolecular assemblies. Dr. Leapman was elected a Fellow of the Microscopy Society of America in 2011. He is currently Editor of the Journal of Microscopy (Oxford), a member of the editorial boards of other microscopy and nanotechnology journals, and has served on numerous national scientific advisory committees. Dr. Leapman is Chief of NIBIB’s Laboratory of Cellular Imaging and Macromolecular Biophysics, while also serving as NIBIB’s Scientific Director since 2006.
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