X-ray Energy-Dispersive Spectrometry During <i>In Situ</i> Liquid Cell Studies Using an Analytical Electron Microscope

Zaluzec, Nestor J.; Burke, M.G.; Haigh, Sarah J.; Kulzick, Matthew A.

doi:10.1017/s1431927614000154

Cited by 68 publications

(58 citation statements)

References 17 publications

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“…This study indicates this technique shows promise for visualizing uptake of iron into the bacteria. In situ spectral imaging via EELS 59 or energy dispersive x-ray spectroscopy (EDS) 60 mapping may provide additional means for visualizing iron uptake, which has only been possible to date in dried bacteria samples using techniques like scanning transmission x-ray microscopy 61 . Finally, further correlative fluorescence and fluid cell electron microscopy studies utilizing fluorescent proteins could allow investigation of the connections between biomolecular processes and biomineralization of magnetosome magnetite nanocrystals.…”

Section: Discussionmentioning

confidence: 99%

Correlative Electron and Fluorescence Microscopy of Magnetotactic Bacteria in Liquid: Toward In Vivo Imaging

et al. 2015

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Magnetotactic bacteria biomineralize ordered chains of uniform, membrane-bound magnetite or greigite nanocrystals that exhibit nearly perfect crystal structures and species-specific morphologies. Transmission electron microscopy (TEM) is a critical technique for providing information regarding the organization of cellular and magnetite structures in these microorganisms. However, conventional TEM can only be used to image air-dried or vitrified bacteria removed from their natural environment. Here we present a correlative scanning TEM (STEM) and fluorescence microscopy technique for imaging viable cells of Magnetospirillum magneticum strain AMB-1 in liquid using an in situ fluid cell TEM holder. Fluorescently labeled cells were immobilized on microchip window surfaces and visualized in a fluid cell with STEM, followed by correlative fluorescence imaging to verify their membrane integrity. Notably, the post-STEM fluorescence imaging indicated that the bacterial cell wall membrane did not sustain radiation damage during STEM imaging at low electron dose conditions. We investigated the effects of radiation damage and sample preparation on the bacteria viability and found that approximately 50% of the bacterial membranes remained intact after an hour in the fluid cell, decreasing to ,30% after two hours. These results represent a first step toward in vivo studies of magnetite biomineralization in magnetotactic bacteria.B iomineralization is a widespread biological phenomenon occurring in living organisms ranging from single cells to complex multicellular organisms. Biomineralization of inorganic materials in single cell organisms is an ideal system for studying fundamental mechanisms of biomineralization 1 . Model systems range from prokaryotic organisms, such as magnetite formation in magnetotactic bacteria 2-4 , to eukaryotic organisms, such as silica biomineralization in diatoms 5,6 . Understanding biomineralization in these organisms in terms of crystal nucleation and growth, as well as the involvement of biological macromolecules and cellular processes, is of fundamental interest to scientists as similar principles can be used to develop synthetic nanomaterials.Magnetite biomineralization by magnetotactic bacteria is a topic of great interest in nanotechnology 7-12 , functional materials [11][12][13][14][15][16] , and astrobiology 17 . Magnetotactic bacteria take up soluble iron species that they use to biomineralize chains of magnetite nanocrystals, known as magnetosomes, in intracellular membrane vesicles 2 . The nanocrystals have nearly perfect mineral crystal structures with consistent species-specific morphologies, leading to well-defined magnetic properties 2,3,9,12,18,19 . As a result, magnetotactic bacteria are one of the best model systems for investigating the molecular mechanisms of biomineralization. Magnetite biomineralization in these bacteria is a complex process involving a number of steps including cellular uptake and reduction of ferric ions, complexation of the iron with membrane proteins, an...

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Section: Discussionmentioning

confidence: 99%

Correlative Electron and Fluorescence Microscopy of Magnetotactic Bacteria in Liquid: Toward In Vivo Imaging

et al. 2015

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“…(S)TEM‐EELS spectroscopy is generally superior to EDS for light element analysis although not all elements relevant to catalysis are suitable for EELS analysis. Unfortunately EELS is strongly influenced by the unavoidable effects of multiple scattering;28 samples should typically be less than ≈100 nm thick in order to minimise multiple scattering and optimise signal‐to‐noise ratios. The two e‐Cell windows have a combined thickness of 80–100 nm even before the gas and specimen are considered.…”

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confidence: 99%

In Situ Industrial Bimetallic Catalyst Characterization using Scanning Transmission Electron Microscopy and X‐ray Absorption Spectroscopy at One Atmosphere and Elevated Temperature

Prestat

Kulzick²,

Dietrich³

et al. 2017

ChemPhysChem

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We have developed a new experimental platform for in situ scanning transmission electron microscope (STEM) energy dispersive X‐ray spectroscopy (EDS) which allows real time, nanoscale, elemental and structural changes to be studied at elevated temperature (up to 1000 °C) and pressure (up to 1 atm). Here we demonstrate the first application of this approach to understand complex structural changes occurring during reduction of a bimetallic catalyst, PdCu supported on TiO2, synthesized by wet impregnation. We reveal a heterogeneous evolution of nanoparticle size, distribution, and composition with large differences in reduction behavior for the two metals. We show that the data obtained is complementary to in situ STEM electron energy loss spectroscopy (EELS) and when combined with in situ X‐ray absorption spectroscopy (XAS) allows correlation of bulk chemical state with nanoscale changes in elemental distribution during reduction, facilitating new understanding of the catalytic behavior for this important class of materials.

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“…The gas environmental cell holder was run with an oxygen/argon mix at 290-350 mbar operated between 150-500°C. The holder had been modified previously, similar to the modifications reported for the liquidcell holder, 35,36 in order to significantly reduce the shadowing of the holder for two of the four available EDX detectors. The internal environment of the holder was shielded from the vacuum of the microscope by two silicon nitride windows, 30 and 50-nm thick.…”

Section: Methodsmentioning

confidence: 99%

An in situ and ex situ TEM study into the oxidation of titanium (IV) sulphide

et al. 2017

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Titanium (IV) sulphide (TiS 2 ) is a layered transition metal dichalcogenide, which we exfoliate using liquid phase exfoliation. TiS 2 is a candidate for being part of a range of future technologies. These applications are varied, and include supercapacitor and battery energy storage devices, catalytic substrates and the splitting of water. The driving force behind our interest was as a material for energy storage devices. Here we investigate a potential failure mechanism for such devices, namely oxidation and subsequent loss of sulphur. This degradation is important to understand, since these applications are highly property-dependent, and changes to the chemistry will result in changes in desired properties. Two approaches to study oxidisation were taken: ex situ oxidation by water and oxygen at room temperature and in situ oxidation by a 5% O 2 /Ar gas at elevated temperatures. Both sources of oxygen resulted in oxidation of the starting TiS 2 flakes, with differing morphologies. Water produced amorphous oxide slowly growing in from the edge of the flakes. Oxygen gas at ≥375°C produced crystalline oxide, with a range of structures due to oxidation initiating from various regions of the observed flakes. npj 2D Materials and Applications (2017) 1:22 ; doi:10.1038/s41699-017-0024-4 INTRODUCTION Titanium (IV) sulphide, TiS 2 , is a candidate for applications in a range of future technologies, including catalytic substrates and the splitting of water, supercapacitors and energy storage devices. TiS 2 is a layered transition metal dichalcogenide (TMD) with hexagonal crystal symmetry and takes the 1T phase and is relatively under explored in two-dimensional form. Each layer consists of three sheets of atoms: the two outer planes are sulphur, coordinated to three titanium atoms with a trigonal pyramidal geometry; the middle plane is titanium and each atom takes octahedral coordination to six sulphur atoms. These atomic sheets are stacked ABC (Supplemental Information Fig. 1), while the layers themselves stack AA in the 1T phase.The excellent capacitive properties of bulk TiS 2 (high energydensity and power-density 1, 2 and excellent electronic conductivity 3 ) have attracted interest since the 1970s, with bulk TiS 2 used as a cathode material in lithium-metal/alloy anode batteries, where lithium metal ions were intercalated, transferring charge to reduce titanium 3d orbitals and causing reduction from Ti 4+ to Ti 3+ (refs. 4, 5). High rates of charging and discharging were demonstrated with near-perfect reversibility. In addition, the material forms a single phase with lithium (Li x TiS 2 ) over the entirety of the range 0 ≤ x ≤ 1, avoiding the need for phase changes upon (de-) lithiation which removes much of the strain induced in cycling, prolonging battery life. However, TMD/Lithium-metal batteries were withdrawn from consumers due to accidents in 1989 where the metallic lithium caught fire as a consequence of shortcircuiting due to lithium-dendrite growth.

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X-ray Energy-Dispersive Spectrometry During In Situ Liquid Cell Studies Using an Analytical Electron Microscope

Cited by 68 publications

References 17 publications

Correlative Electron and Fluorescence Microscopy of Magnetotactic Bacteria in Liquid: Toward In Vivo Imaging

Correlative Electron and Fluorescence Microscopy of Magnetotactic Bacteria in Liquid: Toward In Vivo Imaging

In Situ Industrial Bimetallic Catalyst Characterization using Scanning Transmission Electron Microscopy and X‐ray Absorption Spectroscopy at One Atmosphere and Elevated Temperature

An in situ and ex situ TEM study into the oxidation of titanium (IV) sulphide

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