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This paper presents the application of laboratory X-ray Absorption Fine Structure Spectroscopy (XAFS) in the field of iron coordination chemistry, especially for compounds with larger organic ligands and usually low contents of the metal.

Exposures to exogenous particles is of increasing concern to human health. Characterising the concentrations, chemical species, distribution, and involvement of the stimulus with the tissue microanatomy is essential in understanding the associated biological response. However, no single imaging technique can interrogate all these features at once which confounds and limits correlative analyses. Developments of synchronous imaging strategies, allowing multiple features to be identified simultaneously, is essential to assess spatial relationships between these key features with greater confidence. Here we present data to first highlight complications of correlative analysis between the tissue microanatomy and elemental composition associated with imaging serial tissue sections. This is achieved by assessing both the cellular and elemental distribution in 3-dimensional space using optical microscopy on serial sections and confocal X-ray fluorescence spectroscopy on bulk samples respectively. We propose a new imaging strategy using lanthanide tagged antibodies with X-ray fluorescence spectroscopy. Using simulations, a series of lanthanide tags were identified as candidate labels for scenarios where tissue sections are imaged. The feasibility and value of the proposed approach is shown where an exposure of Ti was identified concurrently with CD45 positive cells at sub-cellular resolutions. Significant heterogeneity in the distribution of exogenous particles and cells can be present between immediately adjacent serial sections showing clear need of synchronous imaging methods. The proposed approach enables elemental compositions to be correlated with the tissue microanatomy in a highly multiplexed and non-destructive manner at high spatial resolutions with the opportunity for subsequent guided analysis.

Amyloid plaques are one of the principal hallmarks of Alzheimer's disease and are mainly composed of Aβ amyloid peptides together with other components such as lipids, cations, or glycosaminoglycans. The structure of amyloid peptide's aggregates is related to the peptide toxicity and highly depends on the aggregation conditions and the presence of cofactors. While fibrillary aggregates are nowadays considered nontoxic, oligomeric/granular (nonfibrillary) aggregates have been found to be toxic. In this work we have characterized in situ two different types of amyloid deposits analyzing sections of the cortex of patients in advanced stages of Alzheimer disease. By combining SR-μFTIR for the study of the secondary structure of the peptide and ThS fluorescence as an indicator of fibrillary structures, we found two types of plaques: ThS positive plaques with a clear infrared band at 1630 cm-1 that would correspond to fibrillary plaques and ThS negative plaques showing a mixture of nonfibrillar β-sheet and unordered aggregated structures that would correspond to the nonfibrillary plaques (plaques with increased unordered structure). The analysis of the FTIR spectra has allowed correlation of lipid oxidation with the presence of nonfibrillary plaques. The metal composition of the two types of plaques has been analyzed using SR-nano-XRF and XANES. The results have shown higher accumulation of iron (mainly Fe2+) in fibrillary plaques than in nonfibrillary ones. However, in nonfibrillary plaques Fe3+ has been found to predominate over Fe2+. The identification of different types of aggregated forms and the different composition of metals found in the different types of plaques could be of paramount importance for the understanding of the development of Alzheimer disease.

The increasing number of patents suggests that the use of nanoparticles (NPs) in agriculture will continue to grow in the future. Properties associated with nanosized objects might be desirable, but may pose a threat to the environment since the fate of nanomaterials is poorly understood. Seed treatment is an extensive practice to provide micronutrients and disease protection. This study investigates the effect of Ag2S NPs, Ag0 NPs, and AgNO3 (1, 100, and 1000 mg Ag per L) on the germination of Phaseolus vulgaris seeds and the mechanism of interaction in the seed coat. Ag treatments did not affect the germination rate. On the other hand, the development of seedlings was significantly improved by Ag2S NPs while AgNO3 showed a negative effect compared to the control (water). Silver from different sources was accumulated and biotransformed along the seed coat. Ag from the AgNO3 treatment was found as AgCl and bound to oxygen, and Ag0 NPs underwent oxidative dissolution forming thiolate complexes. On the other hand, Ag2S NPs did not show any detectable chemical changes. Silver distribution and speciation were investigated in the bean testa using μ-XRF and μ-XANES, while the macromolecular composition was assessed by ATR-FTIR. The Ag biotransformation depended on the source. For the FTIR results, it is possible to verify perturbations in the carbohydrate region as well as changes in the protein region. The combination of these results can contribute to building another step in the understanding of how nanoparticles can improve agricultural inputs and benefit food crops.

The rapid degradation of the environment and unsustainable use of our resources are arguably the two major threats to humanity. Biodiversity, which is an essential prerequisite for resilient ecosys...

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Correction for ‘Spatiotemporal distribution and speciation of silver nanoparticles in the healing wound’ by Marco Roman et al., Analyst, 2020, 145, 6456–6469, DOI: 10.1039/D0AN00607F.

International audience; Carbon nanotubes (CNTs) and titanium dioxide nanoparticles (TiO2-NPs) are among the most used nanomaterials (NMs). However, their impacts especially on the terrestrial ecosystems and on plants are still controversial. Apart from obvious physico-chemical differences, a possible explanation of these contrasting results could be the wide range of methods used to evaluate the toxicity at different levels of plant physiology. Fourier Transformed InfraRed (FTIR) spectroscopy is a sensitive and widely informative technique that probes the chemical composition of plants. In this study, we investigated the impacts of CNTs and TiO2-NPs (100 and 500 mg.kg-1) on tomato plants after 5, 10, 15 and 20 days of exposure in soil. Using morphological parameters, no toxicity was found except after 15 days of exposure (-57% in height and-62% in foliar area for plants exposed to 100 mg.kg-1 TiO2-NPs, but no impact after CNT exposure) while FTIR revealed effects of the two NMs starting after 5 days of exposure and being maximum after 15 days. After spectral data treatment optimization, FTIR results suggested modifications in leaf cell wall components of plants subjected to both NMs. Microarray polymer profiling confirmed changes in xyloglucan and homogalacturonan levels for plants exposed to TiO2-NPs. In summary, FTIR was an effective screening method to evaluate the impacts of NMs on tomato plants and to identify their implications on the plant cell walls.

International audience; Mixotrophic microorganisms are able to use organic carbon as well as inorganic carbon sources and thus, play an essential role in the biogeochemical carbon cycle. In aquatic ecosystems, the alteration of carbon dioxide (CO2) fixation by toxic metals such as cadmium – classified as a priority pollutant – could contribute to the unbalance of the carbon cycle. In consequence, the investigation of cadmium impact on carbon assimilation in mixotrophic microorganisms is of high interest. We exposed the mixotrophic microalga Chlamydomonas reinhardtii to cadmium in a growth medium containing both CO2 and labelled 13C‐[1,2] acetate as carbon sources. We showed that the accumulation of cadmium in the pyrenoid, where it was predominantly bound to sulphur ligands, impaired CO2 fixation to the benefit of acetate assimilation. Transmission electron microscopy (TEM)/X‐ray energy dispersive spectroscopy (X‐EDS) and micro X‐ray fluorescence (μXRF)/micro X‐ray absorption near‐edge structure (μXANES) at Cd LIII‐edge indicated the localization and the speciation of cadmium in the cellular structure. In addition, nanoscale secondary ion mass spectrometry (NanoSIMS) analysis of the 13C/12C ratio in pyrenoid and starch granules revealed the origin of carbon sources. The fraction of carbon in starch originating from CO2 decreased from 73 to 39% during cadmium stress. For the first time, the complementary use of high‐resolution elemental and isotopic imaging techniques allowed relating the impact of cadmium at the subcellular level with carbon assimilation in a mixotrophic microalga.

Many attempts have been made to synthesize cadmium-free quantum dots (QDs), using nontoxic materials, while preserving their unique optical properties. Despite impressive advances, gaps in knowledge of their intracellular fate, persistence, and excretion from the targeted cell or organism still exist, precluding clinical applications. In this study, we used a simple model organism (Hydra vulgaris) presenting a tissue grade of organization to determine the biodistribution of indium phosphide (InP)-based QDs by X-ray fluorescence imaging. By complementing elemental imaging with In L-edge X-ray absorption near edge structure, unique information on in situ chemical speciation was obtained. Unexpectedly, spectral profiles indicated the appearance of In-O species within the first hour post-treatment, suggesting a fast degradation of the InP QD core in vivo, induced mainly by carboxylate groups. Moreover, no significant difference in the behavior of bare core QDs and QDs capped with an inorganic Zn(Se,S) gradient shell was observed. The results paralleled those achieved by treating animals with an equivalent dose of indium salts, confirming the preferred bonding type of In3+ ions in Hydra tissues. In conclusion, by focusing on the chemical identity of indium along a 48 h long journey of QDs in Hydra, we describe a fast degradation process, in the absence of evident toxicity. These data pave the way to new paradigms to be considered in the biocompatibility assessment of QD-based biomedical applications, with greater emphasis on the dynamics of in vivo biotransformations, and suggest strategies to drive the design of future applied materials for nanotechnology-based diagnosis and therapeutics., K.D.W. and L.M. thank the Labex SERENADE (grant Saquado) and the French National Research Agency ANR (grant no. ANR-12-NANO-0007-03 NanoFRET) for funding. P.R. acknowledges financial support from Labex ARCANE (grant QDPhotocat), from CAPES/COFECUB (grant 858/15), and from ANR (grant number ANR-16-CE09-0015-03 Neutrinos). M.M. acknowledges financial support from the European Union’s Horizon 2020 research and innovation programme (Marie Skłodowska-Curie grant agreement no. 660228) and Spanish Juan de la Cierva subprogram.

A multiscale description of (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT6) ceramic is presented. High piezoelectric and electromechanical parameters (d33 = 167 pC/N, kt = 48.6%) were experimentally determined. The ceramic’s crystal structure, after poling, was determined from synchrotron X-ray diffraction. The Rietveld analysis reveals a highly textured BNBT6 perovskite with R3c symmetry. μ-X ray fluorescence on both unpoled and poled ceramics provided evidence of micrometric inhomogeneities in the elemental fluorescence intensities. μ-X ray absorption near edge spectroscopy (μ-XANES) at Ti K-edge spectra present anomalous absorption intensities in some energy intervals. First-principles modeling and linear combination analysis of μ-XANES spectra suggest local variations in the structure of the oxygen octahedron around titanium. The integrated analysis of experiments points toward the existence of micrometric clusters with an enrichment of Bi-O vacancies, distributed randomly at distances of tens of microns. Mentioned microstructural characteristics are consistent with the experimentally determined high piezoelectric and electromechanical parameters.

Despite the increasing attention given to the impacts of nanoplastics in terrestrial environments, there is limited data about the effects on plants, and the quantitative information on uptake. In the present study, wheat plants grown in hydroponics were exposed to Pd-doped nanoplastics. This allowed us to quantify nanoplastics uptake and translocation to the shoots. Visualization of nanoplastics in roots was performed with synchrotron micro X-ray fluorescence (µXRF). Nanoplastics accumulated on the root epidermis, especially at the root tip and in root maturation zones. A close relationship between plant roots, rhizodeposits and nanoplastics behaviour was shown. Reinforcement of the cell wall in roots was evidenced using Fourier transform infrared spectroscopy (FTIR) and synchrotron-computed microtomography (µCT). Synchrotron-computed nanotomography (nanoCT) evidenced the presence of globular structures but they could not be identified as nanoplastics since they were observed both in the control and treated roots. By utilizing the inorganic tracer in the doped-nanoplastics, this study paves the road for elucidating interactions in more complex systems by using an integrative approach combining classical phytotoxicity markers with advanced nanometrology techniques. ISSN:0304-3894 ISSN:1873-3336

International audience; Understanding how essential and toxic elements are distributed in cereal grains is a key to improving the nutritional quality of cereal-based products. The main objective of this work was to characterize the distribution of Cd and of nutrients (notably Cu, Fe, Mn, P, S and Zn) in the durum wheat grain. Laser ablation inductively coupled mass spectrometry and synchrotron micro X-ray fluorescence were used for micro-scale mapping of Cd and nutrients. A dissection approach was used to quantitatively assess the distribution of Cd and nutrients among grain tissues. Micro X-ray absorption near-edge spectroscopy was used to identify the Cd chemical environment in the crease. Cadmium distribution was characterized by strong accumulation in the crease and by non-negligible dissemination in the endosperm. Inside the crease, Cd accumulated most in the pigment strand where it was mainly associated with sulfur ligands. High-resolution maps highlighted very specific accumulation areas of some nutrients in the germ, for instance Mo in the root cortex primordia and Cu in the scutellum. Cadmium loading into the grain appears to be highly restricted. In the grain, Cd co-localized with several nutrients, notably Mn and Zn, which challenges the idea of selectively removing Cd-enriched fractions by dedicated milling process.

This work investigates the mechanisms determining Cr speciation and availability in two different soils polluted with two chromium sources (an industrial sludge, highly polluted with Cr, and Cr(VI) solution) and the influence of these parameters on the recovery of the soil functions related with biological quality and plant growth. The experiment was carried out in greenhouse conditions using 36 pots of 17 kg for the growth of Silene vulgaris for 21 months. Logistic Regression Model using Lasso estimator shows that soil organic matter (SOM) and pH control Cr availability in studied soils. In soils treated with the sludge, X ray Absorption spectroscopy showed that Cr was present as Cr(III), biological quality indicators increased and plants were able to grow. However, in soils polluted with Cr(VI), Cr availability was significantly different in the two soils. In the alkaline and poor in organic matter soil, 12% of Cr(VI) remained in the soil leading to the decrease of soil quality indicators and the total inhibition of plant growth. In the neutral soil, Cr(VI) was totally reduced to Cr(III) by soil organic matter (SOM), quality indicators were not affected and plants grown properly. Infrared Spectroscopy showed that different functional groups reacted with Cr in the two soils. This study highlights the importance to understand the mechanisms underlaying Cr redox and adsorption reactions in Cr polluted soils as they determine the potential recovery of the functions related with biological quality indicators and plant growth. The methodology proposed allows this study in complex soil samples at realistic concentrations and may be useful for risk assessment and for the planning of managing strategies in Cr polluted soils.

Phosphorus (P) resource availability is declining and the efficiency of applied nutrients in agricultural soils is becoming increasingly important. This is especially true for P fertilizers from recycled materials, which often have low plant availability. Specific co-fertilization with ammonium can enhance P plant availability in soils amended with these P fertilizers, and thus the yield of plants. To investigate this effect, we performed a pot experiment with maize in slightly acidic soil (pH 6.9) with one water-soluble (triple superphosphate [TSP]) and two water-insoluble (sewage sludge-based and hyperphosphate [Hyp]) P fertilizers and an ammonium sulfate nitrate with or without a nitrification inhibitor (NI). The dry matter yield of maize was significantly increased by the NI with the Hyp (from 14.7 to 21.5 g/pot) and TSP (from 40.0 to 45.4 g/pot) treatments. Furthermore, P uptake was slightly increased in all three P treatments with the NI, but not significantly. Olsen-P extraction and P K-edge micro-X-ray absorption near-edge structure (XANES) spectroscopy showed that apatite-P of the water-insoluble P fertilizers mobilized during the plant growth period. In addition, novel nitrogen (N) K-edge micro-XANES spectroscopy and the Mogilevkina method showed that the application of an NI increased the fixation of ammonium in detectable hot spots in the soil. Thus, the delay in the nitrification process by the NI and the possible slow-release of temporarily fixed ammonium in the soil resulted in a high amount of plant available ammonium in the soil solution. This development probably decreases the rhizosphere pH due to release of H+ by plants during ammonium uptake, which mobilizes phosphorus in the amended soil and increases the dry matter yield of maize. This is especially important for water-insoluble apatite-based P fertilizers (conventional and recycled), which tend to have poor plant availability. Refereed/Peer-reviewed

Engineering protein-based biomaterials is extremely challenging in bioelectronics, medicine and materials science, as mechanical, electrical and optical properties need to be merged to biocompatibility and resistance to biodegradation, when interfacing with a biological entity. An effective strategy is the engineering of physiological processes in situ, in a non-invasive way, by addition of new properties to endogenous components, producing hybrid materials with new functionality. In this direction, here we show that a green fluorescent semiconducting thiophene dye, DTTO, promotes, in vivo, the biogenesis of fluorescent conductive protein microfibers via metabolic pathways. By challenging the simple freshwater organism Hydra vulgaris with DTTO, we demonstrate the stable incorporation of the dye into supramolecular protein-dye co-assembled microfibers without signs of toxicity. An integrated multilevel analysis including morphological, optical, spectroscopical and electrical characterization shows electrical conductivity of biofibers, opening the door to new opportunities for augmenting electronic functionalities within living tissue, which may be exploited for regulation of cell and animal physiology, or in pathological contexts where enhancing of bioelectrical signaling is demanded.

Additional file 1 Fig. S1. Growth of Brassica oleracea accessions (C6 and F103) cultivated hydroponically for 2 weeks in solutions containing 0.025 mM P (Low P) and 0.25 mM P (High P). Fig. S2. Root (a), shoot (b) and plant (c) phosphorus (P) content of two Brassica oleracea accessions (C6 and F103) grown hydroponically for 2 weeks in solutions containing 0.025 mM P (Low P; LP) and 0.25 mM P (High P; HP). Data are means (n = 5–6) and standard errors. Asterisks indicate statistically significant differences (two-way analysis of variance followed by Holm-Sidak post hoc test at P

The medical application of nanomaterials is growing fast. Amongst the most widely used, silver nanoparticles are antimicrobial agents whose key application is the care of burns and chronic wounds. Still, their absorption, distribution, metabolism and excretion behaviour in vivo has not yet been systematically investigated. We collected full-profile specimens of skin from four hospital patients with mid-to-deep thickness burns or equivalent skin wounds, treated with dressings containing silver nanoparticles or silver sulfadiazine. Synchrotron radiation mu XRF/mu XANES and laser ablation-ICP-MS were used to provide the first semi-quantitative/high resolution direct information on the spatiotemporal distribution and speciation of silver in vivo. The metal was rapidly released onto the wound surface, followed by a significant structure-dependent penetration into the damaged tissues. This was accompanied by sequential processes of metallic silver dissolution, chloride complexation, change to metal-thiol protein complexes, and final mobilization into deeper skin layers towards the vascular networks. Complete local clearance of silver was observed after 12 days of treatment in the case of full healing. The results provide a complete insight into the dynamics of silver in real human wounds, and a new basis for the design of innovative silver nanomaterials with optimal antibacterial efficacy and minimized risk for the patient.

Iron is an essential cofactor for symbiotic nitrogen fixation. It is required by many of the enzymes facilitating the conversion of N2into NH4+by endosymbiotic bacteria living within root nodule cells, including signal transduction proteins, O2homeostasis systems, and nitrogenase itself. Consequently, host plants have developed a transport network to deliver essential iron to nitrogen-fixing nodule cells. Model legumeMedicago truncatula Ferroportin2(MtFPN2) is a nodule-specific gene that encodes an iron-efflux protein. MtFPN2 is located in intracellular membranes in the nodule vasculature, and in the symbiosome membranes that contain the nitrogen-fixing bacteria in the differentiation and early-fixation zones of the nodules. Loss-of-function ofMtFPN2leads to altered iron distribution and speciation in nodules, which causes a reduction in nitrogenase activity and in biomass production. Using promoters with different tissular activity to driveMtFPN2expression inMtFPN2mutants, we determined that MtFPN2-facilitated iron delivery across symbiosomes is essential for symbiotic nitrogen fixation, while its presence in the vasculature does not seem to play a major role in in the conditions tested.

The giant gypsum crystals of Naica cave have fascinated scientists since their discovery in 2000. Human activity has changed the microclimate inside the cave, making scientists wonder about the potential environmental impact on the crystals. Over the last 9 years, we have studied approximately 70 samples. This paper reports on the detailed chemical–structural characterization of the impurities present at the surface of these crystals and the experimental simulations of their potential deterioration patterns. Selected samples were studied by petrography, optical and electronic microscopy, and laboratory X-ray diffraction. 2D grazing incidence X-ray diffraction, X-ray μ-fluorescence, and X-ray μ-absorption near-edge structure were used to identify the impurities and their associated phases. These impurities were deposited during the latest stage of the gypsum crystal formation and have afterward evolved with the natural high humidity. The simulations of the behavior of the crystals in microclimatic chambers produced crystal dissolution by 1–4% weight fraction under high CO2 concentration and permanent fog, and gypsum phase dehydration under air and CO2 gaseous environment. Our work suggests that most surface impurities are of natural origin; the most significant anthropogenic damage on the crystals is the extraction of water from the caves.

Summary Engineering protein-based biomaterials is extremely challenging in bioelectronics, medicine, and materials science, as mechanical, electrical, and optical properties need to be merged to biocompatibility and resistance to biodegradation. An effective strategy is the engineering of physiological processes in situ, by addition of new properties to endogenous components. Here we show that a green fluorescent semiconducting thiophene dye, DTTO, promotes, in vivo, the biogenesis of fluorescent conductive protein microfibers via metabolic pathways. By challenging the simple freshwater polyp Hydra vulgaris with DTTO, we demonstrate the stable incorporation of the dye into supramolecular protein-dye co-assembled microfibers without signs of toxicity. An integrated multilevel analysis including morphological, optical, spectroscopical, and electrical characterization shows electrical conductivity of biofibers, opening the door to new opportunities for augmenting electronic functionalities within living tissue, which may be exploited for the regulation of cell and animal physiology, or in pathological contexts to enhance bioelectrical signaling., Graphical Abstract, Highlights • The oligothiophene DTTO promotes the synthesis of microfibers in Hydra vulgaris • DTTO co-assembles with proteins giving rise to fluorescent and conductive microfibers • The biofiber synthesis is an active process, based on protein synthesis • In situ produced hybrid microfibers have great potential in biolectronics and biomedicine, Supramolecular Chemistry; Bioelectronics; Bioengineering

International audience; Copper oxide nanoparticles (CuO-NPs) have been increasingly released in aquatic ecosystems over the past decades as they are used in many applications. Cu toxicity to different organisms has already been highlighted in the literature, however toxicity mechanisms of the nanoparticulate form remain unclear. Here, we investigated the effect, transfer and localization of CuO-NPs compared to Cu salt on the aquatic plant Myriophyllum spicatum, an ecotoxicological model species with a pivotal role in freshwater ecosystems, to establish a clear mode of action. Plants were exposed to 0.5 mg/L Cu salt, 5 and 70 mg/L CuO-NPs during 96 h and 10 days. Several morphological and physiological endpoints were measured. Cu salt was found more toxic than CuO-NPs to plants based on all the measured endpoints despite a similar internal Cu concentration demonstrated via Cu mapping by micro particle-induced X-ray emission (μPIXE) coupled to Rutherford backscattering spectroscopy (RBS). Biomacromolecule composition investigated by FTIR converged between 70 mg/L CuO-NPs and Cu salt treatments after 10 days. This demonstrates that the difference of toxicity comes from a sudden massive Cu$^{2+}$ addition from Cu salt similar to an acute exposure, versus a progressive leaching of Cu$^{2+}$ from CuO-NPs representing a chronic exposure. Understanding NP toxicity mechanisms can help in the future conception of safer by design NPs and thus diminishing their impact on both the environment and humans.

In this contribution we want to show how the intramineral proteins affect the crystal morphology of calcite crystals grown in vitro. Intramineral proteins from emu eggshells and two crocodile species were isolated, purified by ultrafast liquid chromatography, and characterized by biochemical and biophysical methods. We saw that the crystal habit of calcite was modified when intramineral proteins were present at certain concentration. Therefore, all crystal species were individually characterized by scanning electron microscopy (SEM) and by electron diffraction with an electron-reduced dosage in transmission electron microscopy. Additionally, transversal SEM micrographs of eggshells of four types of species, namely, emu, crocodile, hen, and dinosaur (70 million years old), were compared to track the changes produced by the interacting intramineral proteins. Finally, the organic sulfur content analysis of these eggshells was performed by using X-ray absorption techniques like X-ray fluorescence and X-ray ab...

The Cave of Swords was discovered in 1910 at Naica, Chihuahua, Mexico. During the last century, human presence has changed the microclimate conditions inside this cave, raising the question of whether anthropogenic action resulted in the deterioration of its gypsum single crystals and in the deposition of impurities on their surfaces. The present work provides a detailed characterization of representative samples of this cave and suggests an answer to the origin of the impurities on the surface of these nature-made large crystals. Laboratory and synchrotron characterization techniques are applied. For the first time, the samples single-crystal nature and the fragmentation effect of impurities are characterized. Synchrotron light diffraction measurements performed on a collection of characteristic samples consistently reveal sharp textures, with crystal reciprocal vectors [0,1,0] preferably perpendicular to the samples principal cleavage planes and orientation widths averaging 8°. X-ray diffraction identifies galena, sphalerite, hematite, goethite and cuprite on the crystals’ surface. Diffraction results indicate no correlation between the number of phases of impurities present and crystallinity. Micro X-ray fluorescence clarifies the elemental spatial distribution. The correlations between the elemental distributions confirm the phase identification obtained by diffraction. For Mn and Pb, the correlations point to the presence of amorphous oxides. Minor phases’ characterization suggests they have been deposited on iron oxy-hydroxide substrates. All the identified phases correspond to minerals that were abundantly present in Naica ore deposit before any anthropogenic activity. The impurities on the surface of gypsum crystals at the Cave of Swords were not produced by human presence.

Cadmium (Cd) was shown to co-localise with calcium (Ca) in oxalate crystals in the stems and leaves of Cd tolerant Gomphrena claussenii, but Cd binding remained unresolved. Using synchrotron radiation X-ray absorption near edge spectroscopy we demonstrate that in oxalate crystals of hydroponically grown G. claussenii the vast majority of Cd is bound to oxygen ligands in oxalate crystals (>88%; Cd-O-C coordination) and the remaining Cd is bound to sulphur ligands (Cd-S-C coordination). Cadmium binding to oxalate does not depend on the amount of Ca supplied or from which organs the crystals originate (stems and mature leaves). By contrast, roots contain no oxalate crystals and therein Cd is bound predominantly by S ligands. The potential to remove Cd by extraction of Cd-rich oxalate crystals from plant material should be tested in phytoextraction or phytomining strategies.

We investigated population structure and arsenic bioaccumulation and distribution in zooplankton inhabiting highly contaminated freshwater with arsenic. We collected water and zooplankton samples over a 4 year period, determined environmental temperature as well as water temperature, pH, electrical conductivity (EC), total dissolved solids (TDS), oxidation-reduction potential (ORP), dissolved oxygen (DO), major cations and anions and total arsenic concentration. We identified zooplankton species and determined their abundance, length, sex ratios, and arsenic bioaccumulation and distribution in exposed organisms. At the study site, an extremophile, Paracyclops chiltoni, was found to survive in an environment with high concentration of arsenic, sulfate and fluoride in freshwater as a well-adapted organism. Results showed that the average arsenic concentration in freshwater was 53.64 ± 10.58 mg/L. Exposed organisms of Paracyclops chiltoni showed arsenic accumulation (up to 9.6 ± 5.4 mgAs/kg) in its body, likely in the digestive tract as well as typical abundance and length, which showed a relationship to environmental temperature and oxic conditions in freshwater. Metallotolerant copepods might help to better understand if arsenic methylation processes occur in freshwater aquatic organisms.

The interactions of nanoparticles (NPs) with biochar and soil components may substantially influence NP availability and toxicity to biota. In the present study, earthworms (Eisenia fetida) were exposed for 28 days to a residential or agricultural soil amended with 0–2000 mg of CeO2 NP/kg and with biochar (produced by the pyrolysis of pecan shells at 350 and 600 °C) at various application rates [0–5% (w/w)]. After 28 days, earthworms were depurated and analyzed for Ce content, moisture content, and lipid peroxidation. The results showed minimal toxicity to the worms; however, biochar (350 or 600 °C) was the dominant factor, accounting for 94 and 84% of the variance for the moisture content and lipid peroxidation, respectively, in the exposed earthworms. For both soils with 1000 mg of CeO2/kg at 600 °C, biochar significantly decreased the accumulation of Ce in the worm tissues. Amendment with 350 °C biochar had mixed responses on Ce uptake. Analysis by micro X-ray fluorescence (μ-XRF) and micro X-ray absor...

International audience; Sulfidation is a key process for silver nano-particles released from consumer products in the environment. This study focuses on the impact of a model soil microorganism , Bacillus subtilis, on the fate of pristine and already sulfidized Ag-NPs. The nanoparticles were incubated with the initial growth medium, isolated secretome, and living bacteria, and characterized for their size and morphology, agglomeration state, structure, and Ag speciation. No Ag internalization or sorption on the cell wall was detected. A partial sulfidation, leading to an Ag−Ag 2 S core−shell structure, was observed in the presence of the secretome, and the rate limiting step of the reaction was the oxidation of Ag 0 , and it was favored near the crystal dislocations. The sulfidation was complete in the presence of the living bacteria and followed an indirect pathway. Both crystalline Ag 2 S and amorphous Ag 2 S and/or Ag-thiol were identified. At the opposite, the bacteria had no impact on Ag 2 S. These results suggest that microorganisms participate in the sulfidation of Ag-NPs in aerobic systems such as unsaturated soils, and thus affect the bioavailability of Ag. It is important to take these transformations into account during exposure experiments, since they drastically change the exposure conditions. Finally, the secretome of B. subtilis might be used for the green synthesis of Ag−Ag 2 S core−shell nanoparticles.

The increasing prevalence of tattoos provoked safety concerns with respect to particle distribution and effects inside the human body. We used skin and lymphatic tissues from human corpses to address local biokinetics by means of synchrotron X-ray fluorescence (XRF) techniques at both the micro (μ) and nano (ν) scale. Additional advanced mass spectrometry-based methodology enabled to demonstrate simultaneous transport of organic pigments, heavy metals and titanium dioxide from skin to regional lymph nodes. Among these compounds, organic pigments displayed the broadest size range with smallest species preferentially reaching the lymph nodes. Using synchrotron μ-FTIR analysis we were also able to detect ultrastructural changes of the tissue adjacent to tattoo particles through altered amide I α-helix to β-sheet protein ratios and elevated lipid contents. Altogether we report strong evidence for both migration and long-term deposition of toxic elements and tattoo pigments as well as for conformational alterations of biomolecules that likely contribute to cutaneous inflammation and other adversities upon tattooing.

SummaryBackground Allergic reactions to tattoos are not uncommon. However, identification of the culprit allergen(s) remains challenging. Objectives We present a patient with papulo-nodular infiltration of 20-year-old tattoos associated with systemic symptoms that disappeared within a week after surgical removal of metal osteosynthesis implants from his spine. We aimed to explore the causal relationship between the metal implants and the patient's clinical presentation. Methods Metal implants and a skin biopsy of a reactive tattoo were analysed for elemental contents by inductively coupled plasma mass spectrometry and synchrotron-based X-ray fluorescence (XRF) spectroscopy. Results Nickel (Ni) and chromium (Cr) as well as high levels of titanium (Ti) and aluminium were detected in both the skin biopsy and the implants. XRF analyses identified Cr(III), with Cr(VI) being absent. Patch testing gave negative results for Ni and Cr. However, patch tests with an extract of the implants and metallic Ti on the tattooed skin evoked flare-up of the symptoms. Conclusion The patient's hypersensitivity reaction and its spontaneous remission after removal of the implants indicate that Ti, possibly along with some of the other metals detected, could have played a major role in this particular case of tattoo-related allergy.

Mine Tailings of “La Aurora”, a mining site located in central Mexico, display anomalous concentrations of As, Zn, Pb, Cu and Cd. However, data on their potential toxicity is not available. It is known that toxicity is related to elemental speciation. In this work, we evaluated the biogeochemical dynamics of As in terms of mobility and chemical nature. For this purpose, samples of soils, mine tailings, plants and water were collected. Synchrotron based techniques and chemical fractionation extractions were used to determine As speciation, potential mobility, and bioavailability. Our results showed that As is present in concentrations up to 12,672 ± 34 and 326 ± 10 mg kg−1 in mine tailings and nearby soils, respectively. X-ray Absorption Spectroscopy (XAS) analysis demonstrated that As is present as AsV in a structure similar to that of kankite (FeAsO4·3.5H2O) and beudantite (PbFe3 (AsO4)(SO4)(OH)6). The presence of these mineral structures were confirmed by μ X-Ray Fluorescence and X-ray Absorption Near Edge Structure (μ-XRF/XANES). Arsenic was also detected in plant species growing in the tested soils. The highest As concentrations were determined in the roots of Baccharis salicifolia (up to 44 mg kg−1). In a creek nearby the mine tailings, As levels of 163 ± 15 μg L−1 were quantified. In terms of phytoaccessibility and bioaccessibility, As levels can be considered toxic for both plants and humans. According to sequential extraction results, As is associated mainly with the crystalline Fe-Ox fraction.

Biochar is seeing increased usage as an amendment in agricultural soils but the significance of nanoscale interactions between this additive and engineered nanoparticles (ENP) remains unknown. Corn, lettuce, soybean and zucchini were grown for 28 d in two different soils (agricultural, residential) amended with 0–2000 mg engineered nanoparticle (ENP) CeO2 kg−1 and biochar (350 °C or 600 °C) at application rates of 0–5% (w/w). At harvest, plants were analyzed for biomass, Ce content, chlorophyll and lipid peroxidation. Biomass from the four species grown in residential soil varied with species and biochar type. However, biomass in the agricultural soil amended with biochar 600 °C was largely unaffected. Biochar co-exposure had minimal impact on Ce accumulation, with reduced or increased Ce content occurring at the highest (5%) biochar level. Soil-specific and biochar-specific effects on Ce accumulation were observed in the four species. For example, zucchini grown in agricultural soil with 2000 mg CeO2 kg−1 and 350 °C biochar (0.5–5%) accumulated greater Ce than the control. However, for the 600 °C biochar, the opposite effect was evident, with decreased Ce content as biochar increased. A principal component analysis showed that biochar type accounted for 56–99% of the variance in chlorophyll and lipid peroxidation across the plants. SEM and μ-XRF showed Ce association with specific biochar and soil components, while μ-XANES analysis confirmed that after 28 d in soil, the Ce remained largely as CeO2. The current study demonstrates that biochar synthesis conditions significantly impact interactions with ENP, with subsequent effects on particle fate and effects.

cited By 0; International audience; The green micro-alga Chlamydomonas reinhardtii is commonly used as a model to investigate metallic stress in photosynthetic organisms. The aim of this study was to explore processes implemented by three C. reinhardtii strains to cope with cadmium (Cd), and particularly to evidence Cd sequestration in the cell. For that, we used a combination of subcellular fractionation and chemical imaging (micro X-ray fluorescence (μXRF) and transmission electron microscopy (TEM/X-EDS)) to identify subcellular compartments of Cd accumulation, and X-ray absorption spectroscopy (XAS) to determine chemical Cd speciation. C. reinhardtii wild type strain 11/32b (wt), a newly design strain (pcs1) expressing a modified phytochelatin synthase in the chloroplast and a cell wall less strain CC400 (cw15) were exposed to 70 μM Cd. At this Cd concentration, cell vitality was not affected, however, the strains showed various strategies to cope with Cd stress. In wt, most of Cd was diffused in the whole cell, and complexed by thiol ligands, while the other part was associated with phosphate in vacuolar Ca polyphosphate granules. Thiol ligands increased with exposure time, confirming their important role in Cd stress. In pcs1, Cd was also present as vacuolar Ca polyphosphate granules, and diffused in the cell as Cd-thiol complexes. In addition, while it should be regarded with caution, a minor proportion of Cd complexed by carboxyl groups, was potentially provided by starch produced around the pyrenoid and in the chloroplast. Results suggested that pcs1 uses thiol compounds such as PC to a lesser extent for Cd sequestration than wt. In cw15, an excretion of Cd, Ca polyphosphate granules has to be considered. Finally, Cd was detected in the pyrenoid of all strains.

SUMMARYSymbiotic nitrogen fixation carried out by the interaction between legumes and diazotrophic bacteria known as rhizobia requires of relatively large levels of transition metals. These elements act as cofactors of many key enzymes involved in this process. Metallic micronutrients are obtained from soil by the roots and directed to sink organs by the vasculature, in a process participated by a number of metal transporters and small organic molecules that mediate metal delivery in the plant fluids. Among the later, nicotianamine is one of the most important. Synthesized by nicotianamine synthases (NAS), this non-proteinogenic amino acid forms metal complexes participating in intracellular metal homeostasis and long-distance metal trafficking. Here we characterized theNAS2gene from model legumeMedicago truncatula. MtNAS2 is located in the root vasculature and in all nodule tissues in the infection and fixation zones. Symbiotic nitrogen fixation requires ofMtNAS2function, as indicated by the loss of nitrogenase activity in the insertional mutantnas2-1, a phenotype reverted by reintroduction of a wild-type copy ofMtNAS2. This would be the result of the altered iron distribution innas2-1nodules, as indicated by X-ray fluorescence studies. Moreover, iron speciation is also affected in these nodules. These data suggest a role of nicotianamine in iron delivery for symbiotic nitrogen fixation.Significance StatementNicotianamine synthesis mediated by MtNAS2 is important for iron allocation for symbiotic nitrogen fixation by rhizobia inMedicago truncatularoot nodules.

Significance Silver nanowires are a type of novel fiber that are likely to have wide application in consumer electronics but that can also carry risk for cell internalization and toxicity. Here, we show that silver nanowire toxicity can be greatly diminished by reducing nanowire diameter without affecting device performance. X-ray microscopy and supporting studies revealed that endolysosome membranes can mechanically crumple thin silver nanowires, the likely mechanism for diminishing toxicity., Fibrous particles interact with cells and organisms in complex ways that can lead to cellular dysfunction, cell death, inflammation, and disease. The development of conductive transparent networks (CTNs) composed of metallic silver nanowires (AgNWs) for flexible touchscreen displays raises new possibilities for the intimate contact between novel fibers and human skin. Here, we report that a material property, nanowire-bending stiffness that is a function of diameter, controls the cytotoxicity of AgNWs to nonimmune cells from humans, mice, and fish without deterioration of critical CTN performance parameters: electrical conductivity and optical transparency. Both 30- and 90-nm-diameter AgNWs are readily internalized by cells, but thinner NWs are mechanically crumpled by the forces imposed during or after endocytosis, while thicker nanowires puncture the enclosing membrane and release silver ions and lysosomal contents to the cytoplasm, thereby initiating oxidative stress. This finding extends the fiber pathology paradigm and will enable the manufacture of safer products incorporating AgNWs.

International audience; Increasing evidence indicates the presence of engineered nanoparticles (ENPs) in sewage sludge derived from wastewater treatment. Land application of sewage sludge is, therefore, considered as an important pathway for ENP transfer to the environment. The aim of this work was to understand the effects of sewage sludge containing nano-TiO2 on plants (tomato) when used as an amendment in agricultural soil. We assessed developmental parameters for the entire plant life cycle along with metabolic and bio-macromolecule changes and titanium accumulation in plants. The results suggest that the sewage sludge amendment containing nano-TiO2 increased plant growth (142% leaf biomass, 102% fruit yield), without causing changes in biochemical responses, except for a 43% decrease in leaf tannin concentration. Changes in elemental concentrations (mainly Fe, B, P, Na, and Mn) of plant stem, leaves and, to a lesser extent fruits were observed. Fourier-transformed infrared analysis showed maximum changes in plant leaves (decrease in tannins and lignins and increase in carbohydrates) but no change in fruits. No significant Ti enrichment was detected in tomato fruits. In conclusion, we evidenced no acute toxicity to plants and no major implication for food safety after one plant life cycle exposure.