Applications of synchrotron μ-XRF to study the distribution of biologically important elements in different environmental matrices: A review

Majumdar, Sanghamitra; Peralta-Videa, José R.; Castillo‐Michel, Hiram; Hong, Jie; Rico, Cyren M.; Gardea‐Torresdey, Jorge L.

doi:10.1016/j.aca.2012.09.050

Cited by 106 publications

(53 citation statements)

References 70 publications

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“…This combined approach offers a way to study the role of trace elements in their structural context. ptychography | X-ray fluorescence microscopy | cryogenic biological samples X -ray fluorescence microscopy (XFM) offers unparalleled sensitivity for quantitative mapping of elements, especially trace metals which play a critical role in many biological processes (1)(2)(3). It is complementary to light microscopy, which can study some elemental content in live cells (with superresolution techniques possible) but which is more difficult to quantitate because it depends on the binding affinities of fluorophores.…”

mentioning

confidence: 99%

Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

Deng

Vine

Chen

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

164

131

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Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolution beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and ∼90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. This combined approach offers a way to study the role of trace elements in their structural context. ptychography | X-ray fluorescence microscopy | cryogenic biological samples X -ray fluorescence microscopy (XFM) offers unparalleled sensitivity for quantitative mapping of elements, especially trace metals which play a critical role in many biological processes (1-3). It is complementary to light microscopy, which can study some elemental content in live cells (with superresolution techniques possible) but which is more difficult to quantitate because it depends on the binding affinities of fluorophores. However, XFM does not usually show much cellular ultrastructure, because the light elements (such as H, C, N, and O, which are the main constituents of biological materials) have low fluorescence yield (4). At the multi-keV X-ray energies needed to excite most X-ray fluorescence lines of interest, these light elements show little absorption contrast, but phase contrast can be used to image cellular structure (5, 6) and this can be combined with scanned-beam XFM (7-11).One can also acquire phase-contrast X-ray images with a resolution beyond X-ray lens limits by recording the diffraction pattern from a coherently illuminated, noncrystalline sample in an approach called coherent diffraction imaging (CDI) (12). This approach has been used to image isolated dried cells (13-15), and 3-nm resolution has been achieved when imaging silver nanocubes (16). The traditional CDI approach requires that samples meet a so-called "finite support" (17) requirement with no observable scattering outside of a defined region; although some limited success has been obtained (18,19), this finite support condition has proven difficult to achieve with single cells surrounded by ice layers. Ptychography (20-22) is a recently realized CDI method [with an older history (23)] that circumvents this isolated cell requirement by instead scanning a limitedsize coherent illumination spot across the sample. Ptychography has been used to image freeze-dried diatoms at 30-nm resolution (24) and bacter...

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mentioning

confidence: 99%

Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

Deng

Vine

Chen

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

164

131

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“…Synchrotron-based microfocused X-rayfluorescence (μ-SXRF) with microX-ray absorption near-edge structure (μ-XANES) or microXray diffraction (μ-XRD) are currently the most powerful set of techniques used for a complete characterization of biological samples. Among the set of techniques, μ-SXRF is very useful, allowing in situ mapping of nanoparticles with high sensitivity, negligible sample damage, and enable tuning of the incident energy as desired (Ma et al, 2011;Majumdar et al, 2012;Hernandez-Viezcas et al, 2013;Hummer and Rompel, 2013). Other promising advances include single particle inductively coupled plasma-mass spectrometry (spICP-MS), solid sampling highresolution-continuum source atomic absorption spectrometry (HR-CS AAS) and two-photon excitation microscopy (TPEM) (Wild and Jones, 2009;Feichtmeier and Leopold, 2013;Gray et al, 2013).…”

Section: Perspectives and Research Prioritiesmentioning

confidence: 99%

Interactions between engineered nanomaterials and agricultural crops: implications for food safety

Deng

White

Xing

2014

J. Zhejiang Univ. Sci. A

117

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Engineered nanomaterials (ENMs) are being discharged into the environment and to agricultural fields, with unknown impacts on crop species. In this paper, we review the literature on ENMs uptake, translocation/distribution, and generational transmission in various crop species, as well as potential material trophic transfer. Previous studies reveal that ENM-exposed crops exhibit adaptive processes in response to stress, including endocytosis/endosome activities, production of antioxidant enzymes, regulation of genes related to cell division/extension and membrane transport. Some agronomic traits of crops are compromised during the adaption response, including photosynthesis, fruit yields, nutritional quality and nitrogen fixation. Cultivation of crops in ENMs-contaminated environments has unknown implications for food safety and quality. Notably, mechanisms underlying ENMs phytotoxicity and bioavailability are unclear. Additional investigations focused on developing novel techniques for in vivo identification/characterization of ENMs are critically needed. Given the abundance of uncertainty in the literature, it is clear that more research is urgently needed in the area of ENMs-crop interactions; only then can one accurately assess exposure, risk, and overall implications for food safety and also enable guidance development for the sustainable implementation of nanotechnology in agriculture and food production/manufacturing.

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“…Micro-X-ray fluorescence (μ-XRF) analysis 1 is applied in environmental sciences, 2,3 geological applications, 4,5 cultural heritage studies, 6 archeology, 7 and in the biomedical, 8,9 chemical, 10,11 and forensic 12 domains. Usually the related experiments are realized at advanced research facilities, i.e., third generation synchrotron sources, where the bright, coherent, polarized, energy-tunable, and monochromatic Xray beams can be used for fluorescence, scattering, diffraction, or absorption experiments.…”

Section: Introductionmentioning

confidence: 99%

Laboratory-based micro-X-ray fluorescence setup using a von Hamos crystal spectrometer and a focused beam X-ray tube

Kayser

Błachucki

Dousse

et al. 2014

Review of Scientific Instruments

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The high-resolution von Hamos bent crystal spectrometer of the University of Fribourg was upgraded with a focused X-ray beam source with the aim of performing micro-sized X-ray fluorescence (XRF) measurements in the laboratory. The focused X-ray beam source integrates a collimating optics mounted on a low-power micro-spot X-ray tube and a focusing polycapillary half-lens placed in front of the sample. The performances of the setup were probed in terms of spatial and energy resolution. In particular, the fluorescence intensity and energy resolution of the von Hamos spectrometer equipped with the novel micro-focused X-ray source and a standard high-power water-cooled X-ray tube were compared. The XRF analysis capability of the new setup was assessed by measuring the dopant distribution within the core of Er-doped SiO 2 optical fibers.

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Applications of synchrotron μ-XRF to study the distribution of biologically important elements in different environmental matrices: A review

Cited by 106 publications

References 70 publications

Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

Interactions between engineered nanomaterials and agricultural crops: implications for food safety

Laboratory-based micro-X-ray fluorescence setup using a von Hamos crystal spectrometer and a focused beam X-ray tube

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