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SummaryTomography in a focused ion beam (FIB) scanning electron microscope (SEM) is a powerful method for the characterization of three-dimensional micro-and nanostructures. Although this technique can be routinely applied to conducting materials, FIB-SEM tomography of many insulators, including biological, geological and ceramic samples, is often more difficult because of charging effects that disturb the serial sectioning using the ion beam or the imaging using the electron beam. Here, we show that automatic tomography of biological and geological samples can be achieved by serial sectioning with a focused ion beam and block-face imaging using low-kV backscattered electrons. In addition, a new ion milling geometry is used that reduces the effects of intensity gradients that are inherent in conventional geometry used for FIB-SEM tomography.

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SummaryAtherogenesis is a pathological condition in which changes in the ultrastructure and in the localization of proteins occur within the vasculature during all stages of the disease. To gain insight in those changes, high-resolution imaging is necessary. Some of these changes will only be present in a small number of cells, positioned in a 'sea' of non-affected cells. To localize this relatively small number of cells, there is a need to first navigate through a large area of the sample and subsequently zoom in onto the area of interest. This approach enables the study of specific cells within their in vivo environment and enables the study of (possible) interactions of these cells with their surrounding cells/environment. The study of a sample in a correlative way using light and electron microscopy is a promising approach to achieve this; however, it is very laborious and additional ultrastructural techniques might be very valuable to find the places of interest.In this report we show that the focused ion beam-scanning electron microscope is a powerful tool to study biological specimens in a correlative way. With this microscope one can scan for the area of interest at low magnification, in this case the atherosclerotic plaque, and subsequently zoom in, for further analysis on an ultrastructural level, rendering valuable and detailed two-and three-dimensional information of, in this case, the endothelial cells and the vessel wall. Moreover, in combination with pre-embedment labelling of surface exposed antigens, the method allows insight into the 3D distribution of these markers.

Emulsions stabilized by solid particles, called Pickering emulsions, offer promising applications in drug delivery, cosmetics, food science and the manufacturing of porous materials. This potential stems from their high stability against coalescence and 'surfactant-free' nature. Generally, Pickering emulsions require that the solid particles are wetted by both phases and as a result, the adsorption free energy is often large with respect to the thermal energy (kBT). Here we provide the first experimental proof for an alternative scenario: non-touching (effectively non-wetting), charged, particles that are completely immersed in the oil phase through a balance of charge induced attractions and repulsions caused by van der Waals forces. These particles nonetheless stabilize the emulsion. The main advantage of this novel adsorption mechanism is that these particles can easily be detached from the interface simply by adding salt. This not only makes the finding fundamentally of interest, but also enables a triggered de-emulsification and particle recovery, which is useful in fields like enhanced oil recovery, heterogeneous catalysis, and emulsion polymerization.