Soft X-ray induced radiation damage in thin freeze-dried brain samples studied by FTIR microscopy.

In order to push the spatial resolution limits to the nanoscale, synchrotron-based soft X-ray microscopy (XRM) experiments require higher radiation doses to be delivered to materials. Nevertheless, the associated radiation damage impacts on the integrity of delicate biological samples. Herein, the extent of soft X-ray radiation damage in popular thin freeze-dried brain tissue samples mounted onto Si3N4 membranes, as highlighted by Fourier transform infrared microscopy (FTIR), is reported. The freeze-dried tissue samples were found to be affected by general degradation of the vibrational architecture, though these effects were weaker than those observed in paraffin-embedded and hydrated systems reported in the literature. In addition, weak, reversible and specific features of the tissue-Si3N4 interaction could be identified for the first time upon routine soft X-ray exposures, further highlighting the complex interplay between the biological sample, its preparation protocol and X-ray probe.

X-ray ptychography using randomized zone plates.

We have developed a randomized grating condenser zone plate (GCZP) that provides a µm-scale probe for use in x-ray ptychography. This delivers a significantly better x-ray throughput than probes defined by pinhole apertures, while providing a clearly-defined level of phase diversity to the illumination on the sample, and helping to reduce the dynamic range of the detected signal by spreading the zero-order light over an extended area of the detector. The first use of this novel x-ray optical element has been demonstrated successfully for both amplitude and phase contrast imaging using soft x-rays on the TwinMic beamline at the Elettra synchrotron.

Phase-diverse Fresnel coherent diffractive imaging of malaria parasite-infected red blood cells in the water window.

Phase-diverse Fresnel coherent diffractive imaging has been shown to reveal the structure and composition of biological specimens with high sensitivity at nanoscale resolution. However, the method has yet to be applied using X-ray illumination with energy in the so-called 'water-window' that lies between the carbon and oxygen K edges. In this range, differences in the strength of the X-ray interaction for protein based biological materials and water is increased. Here we demonstrate a proof-of-principle application of FCDI at an X-ray energy within the water-window to a dehydrated cellular sample composed of red blood cells infected with the trophozoite stage of the malaria parasite, Plasmodium falciparum. Comparison of the results to both optical and electron microscopy shows that the correlative imaging methods that include water-window FCDI will find utility in studying cellular architecture.

Unexpected silicon localization in calcium carbonate exoskeleton of cultured and fossil coccolithophores.

Coccolithophores, marine calcifying phytoplankton, are important primary producers impacting the global carbon cycle at different timescales. Their biomineral structures, the calcite containing coccoliths, are among the most elaborate hard parts of any organism. Understanding the morphogenesis of coccoliths is not only relevant in the context of coccolithophore eco-physiology but will also inform biomineralization and crystal design research more generally. The recent discovery of a silicon (Si) requirement for crystal shaping in some coccolithophores has opened up a new avenue of biomineralization research. In order to develop a mechanistic understanding of the role of Si, the presence and localization of this chemical element in coccoliths needs to be known. Here, we document for the first time the uneven Si distribution in Helicosphaera carteri coccoliths through three synchrotron-based techniques employing X-ray Fluorescence and Infrared Spectromicroscopy. The enrichment of Si in specific areas of the coccoliths point to a targeted role of this element in the coccolith formation. Our findings mark a key step in biomineralization research because it opens the door for a detailed mechanistic understanding of the role Si plays in shaping coccolith crystals.

Phase II study of cabazitaxel as second-third line treatment in patients with metastatic adrenocortical carcinoma.

BACKGROUND: Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with a poor prognosis. No efficacious treatment options are currently available for patients with advanced metastatic disease with disease progression to standard etoposide, doxorubicin, cisplatin and mitotane (EDP-M) therapy. We assessed the activity and tolerability of cabazitaxel as a second/third-line approach in metastatic ACC. PATIENTS AND METHODS: Patients included in this single-center, phase II study (ClinicalTrials.gov identifier NCT03257891) had disease progression to a cisplatin-containing regimen (such as EDP) plus mitotane, plus/minus a further chemotherapy line. Cabazitaxel was administered intravenously at 25 mg/m2 on day 1 of a 21-day cycle, for a maximum of six cycles. The primary endpoint was a disease control rate after 4 months. RESULTS: From March 2018 to September 2019, 25 eligible patients were enrolled. A disease control rate after 4 months was obtained in six patients (24%). No patients attained a disease response according to RECIST 1.1, 9 patients (36%) had stable disease and 16 patients (64%) progressive disease. Median progression-free survival and overall survival were 1.5 months (range 0.3-7 months) and 6 months (range 1-22.2 months), respectively. Cabazitaxel therapy was well tolerated and only three (12%) patients developed grade 3 toxicity which were nausea in one patient (4%) and anemia in two patients (8%). CONCLUSIONS: Cabazitaxel has a manageable toxicity profile but is poorly active as second/third-line treatment in advanced ACC patients. These results do not support further evaluation of cabazitaxel in this setting.

An in situ electrochemical soft X-ray spectromicroscopy investigation of Fe galvanically coupled to Au.

In this paper we report a pioneering electrochemical study of the galvanic coupling of Au and Fe in neutral aqueous solutions containing sulphate and fluoride ions, carried out by synchrotron-based in situ soft X-ray imaging and X-ray absorption microspectroscopy. The investigation was performed at the TwinMic X-ray Microscopy station at Elettra synchrotron facility combining X-ray imaging with µ-XAS with sub-micron lateral resolution. Using a purposely developed model thin-layer wet cell the morphology and chemical evolution of Fe electrodes in contact with aqueous solutions containing Na2SO4 and NaF have been investigated. The obtained results shed light on fundamental aspects regarding stability of Fe-based metallic bipolar plates in different electrochemical environments, an important issue for durability of polymer-electrolyte fuel cells. Imaging morphological features typical of the relevant electrochemical processes with chemical contrast, yields details on the spatial distribution and speciation of Fe resulting from corrosion of the Fe electrodes in the working fuel cells.

The first observation of osmotically neutral sodium accumulation in the myocardial interstitium.

The aim of this study was the detection and quantification of the Na+ depositions in the extracellular matrix of myocardial tissue, which are suggested to be bound by negatively charged glycosaminoglycan (GAG) structures. The presented experimental results are based on high resolution X-ray fluorescence (XRF) spectromicroscopy technique used to perform a comparative analysis of sodium containment in intracellular and interstitial spaces of cardiac tissues taken from animals selected by low and high sodium intake rates. The experimental results obtained show that high sodium daily intake can result in a remarkable increase of sodium content in the myocardial interstitium.

A new method for municipal solid waste incinerator (MSWI) fly ash inertization, based on colloidal silica.

Municipal solid waste incineration (MSWI) is a straightforward way to manage waste, however the disposal of process byproducts, mainly bottom and fly ash, is still a problem, because of their hazardous contents. Fly ash is a byproduct of many other processes that involve combustion to produce energy. In this paper we present and discuss a new method for MSWI fly ash inertization, mainly based on the use of colloidal silica as a stabilization agent for metals. In the patented procedure, fly ash of different provenance can be used to produce an inert and non-hazardous material, that can be reused. In fact to make the recovery process more efficient, landfilling should be totally avoided. For this reason, to enhance the possibility of reuse, a washing process, for salts recovery, is proposed as a final step of the inertization procedure. The obtained inert material is called COSMOS (COlloidal Silica Medium to Obtain Safe inert), and it is composed of calcium carbonate, calcium sulfate, silicon oxide and a wide quantity of non-soluble amorphous compounds. COSMOS does not contain any corrosive salts. This makes it extremely interesting for cement industry applications with several other advantages, and environmental benefits. The new proposed inertization procedure appears very promising, because it allows MSWI fly ash to be considered a valuable resource. Thanks to the obtained results, a demonstration project, in the frame of LIFE+, has been funded by the European Commission (LIFE+ 2008 project ENV/IT/000434, ).

Concentration and distribution of silica nanoparticles in colon cancer cells assessed by synchrotron based X-ray techniques.

The quantitative uptake of Silica nanoparticles (SiNPs), although representing an essential prerequisite for their theranostic use, is difficult to address and it is still not utterly investigated. In this study, we tested the uptake and toxicity of two different types of luminescent core-shell silica-PEG (polyethylene glycol) nanoparticles SiNP and their carboxylate analogues on human adenocarcinoma cell line LoVo. We assessed the intracellular spatial distribution and concentration of Si element in the cell by a state-of-the-art approach merging synchrotron-based X-ray techniques (XRFM) with scanning transmission X-Ray microscopy (STXM). The concentration maps of Si obtained reflect the distribution of the SiNPs. In addition, we calculated the number of SiNPs per volume unit in each single cell, quantitating the exact amount of conveyed particles. The absence of effects on proliferation and cell death was confirmed by viability assays, morphological analysis and cytofluorimetric evaluation of ROS content. The three-dimensional analysis of intracellular uptake of both types of nanoparticles (with different surface charge) was performed by confocal fluorescence microscopy, which showed a main localization in the cytosolic region with no sign of nuclear uptake.

Combining in-cell NMR and X-ray fluorescence microscopy to reveal the intracellular maturation states of human superoxide dismutase 1.

An integrated approach which combines in-cell NMR spectroscopy with optical and X-ray fluorescence microscopy was developed to describe the intracellular maturation state of human Cu,Zn-SOD1. Microscopy data show a correlation between the intracellular levels of SOD1 and the content of zinc, corresponding to zinc binding to SOD1 observed by in-cell NMR.

Soft X-Ray Microscopy Radiation Damage On Fixed Cells Investigated With Synchrotron Radiation FTIR Microscopy.

Radiation damage of biological samples remains a limiting factor in high resolution X-ray microscopy (XRM). Several studies have attempted to evaluate the extent and the effects of radiation damage, proposing strategies to minimise or prevent it. The present work aims to assess the impact of soft X-rays on formalin fixed cells on a systematic manner. The novelty of this approach resides on investigating the radiation damage not only with XRM, as often reported in relevant literature on the topic, but by coupling it with two additional independent non-destructive microscopy methods: Atomic Force Microscopy (AFM) and FTIR Microscopy (FTIRM). Human Embryonic Kidney 293 cells were exposed to different radiation doses at 1 keV. In order to reveal possible morphological and biochemical changes, the irradiated cells were systematically analysed with AFM and FTIRM before and after. Results reveal that while cell morphology is not substantially affected, cellular biochemical profile changes significantly and progressively when increasing dose, resulting in a severe breakdown of the covalent bonding network. This information impacts most soft XRM studies on fixed cells and adds an in-depth understanding of the radiation damage for developing better prevention strategies.

Microscopic biomineralization processes and Zn bioavailability: a synchrotron-based investigation of Pistacia lentiscus L. roots.

Plants growing on polluted soils need to control the bioavailability of pollutants to reduce their toxicity. This study aims to reveal processes occurring at the soil-root interface of Pistacia lentiscus L. growing on the highly Zn-contaminated tailings of Campo Pisano mine (SW Sardinia, Italy), in order to shed light on possible mechanisms allowing for plant adaptation. The study combines conventional X-ray diffraction (XRD) and scanning electron microscopy (SEM) with advanced synchrotron-based techniques, micro-X-ray fluorescence mapping (µ-XRF) and X-ray absorption spectroscopy (XAS). Data analysis elucidates a mechanism used by P. lentiscus L. as response to high Zn concentration in soil. In particular, P. lentiscus roots take up Al, Si and Zn from the rhizosphere minerals in order to build biomineralizations that are part of survival strategy of the species, leading to formation of a Si-Al biomineralization coating the root epidermis. XAS analysis rules out Zn binding to organic molecules and indicates that Zn coordinates Si atoms stored in root epidermis leading to the precipitation of an amorphous Zn-silicate. These findings represent a step forward in understanding biological mechanisms and the resulting behaviour of minor and trace elements during plant-soil interaction and will have significant implications for development of phytoremediation techniques.

Soft X-ray spectromicroscopy using ptychography with randomly phased illumination.

Ptychography is a form of scanning diffractive imaging that can successfully retrieve the modulus and phase of both the sample transmission function and the illuminating probe. An experimental difficulty commonly encountered in diffractive imaging is the large dynamic range of the diffraction data. Here we report a novel ptychographic experiment using a randomly phased X-ray probe to considerably reduce the dynamic range of the recorded diffraction patterns. Images can be reconstructed reliably and robustly from this setup, even when scatter from the specimen is weak. A series of ptychographic reconstructions at X-ray energies around the L absorption edge of iron demonstrates the advantages of this method for soft X-ray spectromicroscopy, which can readily provide chemical sensitivity without the need for optical refocusing. In particular, the phase signal is in perfect registration with the modulus signal and provides complementary information that can be more sensitive to changes in the local chemical environment.

Metal fractionation in soils and assessment of environmental contamination in Vallecamonica, Italy.

Metal contamination was investigated in soils of the Vallecamonica, an area in the northern part of the Brescia province (Italy), where ferroalloy industries were active for a century until 2001. The extent in which emissions from ferroalloy plants affected metal concentration in soils is not known in this area. In this study, the geogenic and/or anthropogenic origin of metals in soils were estimated. A modified Community Bureau of Reference sequential chemical extraction method followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses were employed to evaluate the potential bioavailability of Al, Cd, Mn, Fe, Cr, Zn, and Pb in soils. Principal component analysis (PCA) was used to assess the relationships among metal sources in soil samples from different locations. This approach allowed distinguishing of different loadings and mobility of metals in soils collected in different areas. Results showed high concentrations and readily extractability of Mn in the Vallecamonica soils, which may suggest potential bioavailability for organisms and may create an environmental risk and potential health risk of human exposure.

Airborne particulate matter (PM) filter analysis and modeling by total reflection X-ray fluorescence (TXRF) and X-ray standing wave (XSW).

This work is presented as an improvement of a recently introduced method for airborne particulate matter (PM) filter analysis [1]. X-ray standing wave (XSW) and total reflection X-ray fluorescence (TXRF) were performed with a new dedicated laboratory instrumentation. The main advantage of performing both XSW and TXRF, is the possibility to distinguish the nature of the sample: if it is a small droplet dry residue, a thin film like or a bulk sample. Another advantage is related to the possibility to select the angle of total reflection to make TXRF measurements. Finally, the possibility to switch the X-ray source allows to measure with more accuracy lighter and heavier elements (with a change in X-ray anode, for example from Mo to Cu). The aim of the present study is to lay the theoretical foundation of the new proposed method for airborne PM filters quantitative analysis improving the accuracy and efficiency of quantification by means of an external standard. The theoretical model presented and discussed demonstrated that airborne PM filters can be considered as thin layers. A set of reference samples is prepared in laboratory and used to obtain a calibration curve. Our results demonstrate that the proposed method for quantitative analysis of air PM filters is affordable and reliable without the necessity to digest filters to obtain quantitative chemical analysis, and that the use of XSW improve the accuracy of TXRF analysis.