de Jonge, Niels | Mølhave, Kristian | Alloyeau, Damien
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DOI:de Jonge, Niels | Peckys, Diana B.
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Electron microscopy of biological cells in liquid provides unique nanoscale information. A highly attractive idea is the capability to also study physiological processes of live cells with electron microscopy. However, this idea seems unrealistic because the minimal needed electron dose to obtain contrast is already many orders of magnitude above the lethal dose known to cause reproductive-cell death. We show here that claims of electron microscopy of viable cells in recent reports are based on a questionable interpretation of the used fluorescence live/dead assay. A practical alternative to study biological processes is correlative light and electron microscopy.
de Jonge, Niels | Ross, Frances M. | Wang, Chongmin
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DOI:Peckys, Diana | Korf, Ulrike | Wiemann, Stefan | de Jonge, Niels
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DOI:Peckys, Diana B. | Alansary, Dalia | Niemeyer, Barbara A. | de Jonge, Niels
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DOI:Peckys, Diana B. | de Jonge, Niels
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DOI:Ross, Frances M. | Wang, Chongmin | de Jonge, Niels
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Transmission electron microscopy is a powerful technique for the analysis of solid samples, but it can also be used to image in liquid environments, gaining a unique view of processes and structures in liquids. Here, we describe recent developments in electron microscopy of liquids and discuss applications in several areas. We first describe closed-liquid-cell microscopy with its opportunities for visualizing electrochemical processes. We then discuss imaging of low-vapor-pressure liquids relevant to the operation of rechargeable batteries. Finally, we describe imaging of thick biological materials to obtain information on membrane proteins in intact mammalian cells that cannot be observed classically under dry or frozen conditions. Electron microscopy in liquid environments is developing rapidly and has the potential to solve key problems in materials science, physics, chemistry, and biology.
Verch, Andreas | de Jonge, Niels
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DOI:Weber, Eva | Verch, Andreas | Levy, Davide | Fitch, Andy N. | Pokroy, Boaz
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Transition from an amorphous to a crystalline phase and stabilization of amorphous phases is a common strategy in biomineralization. Although no such phenomenon has yet been reported for biogenic calcium oxalate systems, it was recently demonstrated for synthetic calcium oxalate monohydrate (COM). Here we focused on COM raphides—needle shaped biominerals—synthesized by Duckweed. Although these raphides show some birefringence in polarized light, implying their crystallinity, they diffracted poorly when examined by x-ray diffraction in our experiments. By means of transmission electron microscopy coupled with electron diffraction experiments we demonstrated that raphides from Duckweed are completely amorphous in their tip region and transform into a crystalline phase under the electron beam after a few seconds of exposure. To the best of our knowledge, this is the first report on biogenic amorphous calcium oxalate produced by a living organism.
Kraß, Marc-Dominik | Gosvami, Nitya Nand | Carpick, Robert W. | Müser, Martin H. | Bennewitz, Roland
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Hexadecane exhibits pronounced molecular layering upon confinement to gaps of a few nanometer width which is discussed for its role in boundary lubrication. We have probed the mechanical properties of the confined layers with the help of an atomic force microscope, by quasi-static normal force measurements and by analyzing the lateral tip motion of a magnetically actuated torsional cantilever oscillation. The molecular layering is modeled by a oscillatory force curve and the tip approach is simulated assuming thermal equilibrium correlations in the liquid. The shear response of the confined layers reveals gradually increasing stiffness and viscous dissipation for a decreasing number of confined layers.