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Open Access
Abstract: In recent years, elevated concentrations of arsenic (As) have been detected in the Tertiary detrital aquifer of Madrid. A significant number of areas where waste from old mining operations, rich in metals and metalloids, accumulate may partially explain contamination events by toxic elements. In these environments, colloidal particles can act as nanovectors for the dispersion of As, enhancing its migration and contamination of surrounding soils. This work studies the mobilization of As-rich colloids from a waste zone of an old mining operation in the Community of Madrid. These wastes, mainly composed of arsenopyrite [FeAsS] ([As] = 0.2 g kg-1), are deposited near a natural stream and exposed to environmental conditions. In order to follow the mobility of As-rich colloids, the combined techniques of asymmetric flow field flow fractionation and inductively coupled plasma mass spectrometry (AF4-ICP-MS) are used to obtain the size distribution of the colloidal fraction and associated As, while X-ray absorption spectroscopy (XAS) techniques are utilized for the study of the chemical speciation of As in the solid phase. In addition, geochemical modeling allows prediction of the thermodynamically favored phases in each of the studied areas. The mobilization of colloidal As from mining waste to water and soil located up to 1 km from the source of contamination is described. The essential role of colloidal Fe oxyhydroxides as As mobilizing nanovectors is also highlighted.
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Dec 2025
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Abstract: Cerium oxide nanoparticles (CeO2 NPs), a few nanometers in diameter, exhibit strong antioxidant and anti-inflammatory activity and are considered promising candidates for the treatment of ocular diseases. This study investigated the impact of CeO2 NPs, both in their naked form, and formulated as eye drops, on the bacteria inhabiting the ocular surface. The microbiome from healthy eyes was characterized through 16 S rRNA amplicon sequencing. The dominant bacterial genera included Staphylococcus, with lower abundances of Corynebacterium and Streptococcus, varying among the samples. Eye bacteria were isolated and exposed to both forms of CeO2 NPs to investigate cell growth, viability, and gene expression. Neither naked CeO2 NPs nor eye drop formulation affected the growth of Staphylococcus aureus and Staphylococcus epidermidis. In S. aureus, CeO2 caused down-regulation of rho (naked CeO2 NPs) and recA (eye drop form) genes related to the termination of transcription and DNA damage response, respectively. In S. epidermidis, the expression of lexA, recA, ftsZ, rho and icaC remained comparable between treated and control samples, while DNA damage response genes lexA and recA were up-regulated in C. amycolatum following exposure to CeO2 eye drops. These gene expression patterns revealed subtle changes in specific bacteria, indicating a short-term adaptive response to eye drop formulations. Overall, these results suggest that CeO2 NP eye drops have a minimal impact on the isolated bacterial strains. Nonetheless, comprehensive in vivo and clinical studies are necessary to validate these findings, given the inherent limitations of in vitro assays.
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Dec 2025
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Abstract: To address concerns about the ever-increasing release of photocatalytic engineered cerium oxide nanoparticles (nCeO2) into freshwaters, field experiments were conducted to evaluate their impacts on diatom-dominated assemblages of phytoplankton and phytobenthos from UK streams. Outcomes were compared to those obtained in laboratory toxicity tests on the freshwater diatom Fistulifera pelliculosa. Exposure to an environmentally relevant concentration (0.05 mg/L nCeO2) led to two significant stimulatory responses in photosynthetic performance, averaging ~15%, in phytobenthos, compared to a single minor inhibitory response (~7%) in phytoplankton, relative to controls. At supra-environmental exposures (5.0 mg/L nCeO2) two significant inhibitory responses (~13%) were measured in photosynthetic performance, in phytoplankton and only one (~11%) for phytobenthos, relative to controls. No significant impacts were detected in the benthic diatom Fistulifera pelliculosa at the same two concentrations, their release of copious extracellular polymeric substances likely reduced direct contact with nCeO2. Many diatoms contribute to the pool of natural organic matter in aquatic ecosystems through release extracellular polymeric substances (EPS). Phytobenthic cells embedded in the EPS matrix, may have received less exposure to nCeO2 than the phytoplankton. We consider the extent to which media-dependent nanoparticle characteristics and behaviour, including Ce3+/Ce4+ ratios, zeta-potential, hydrodynamic diameter, the polydispersity index, nanoparticle stabilisation and nanoparticle settlement may account for the observed differences. We propose that EPS-secreting diatoms would make ideal model species for future laboratory toxicity testing of newly emerging nanoparticle sub-types, as they generate environmentally realistic conditions, in artificial culture media, more closely representing those experienced by natural assemblages of phytoplankton and phytobenthos.
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Nov 2025
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B18-Core EXAFS
I14-Hard X-ray Nanoprobe
I18-Microfocus Spectroscopy
I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[33674, 35117, 35776, 40942, 37789]
Open Access
Abstract: Achieving safe and sustainable nanomaterials remains challenging—not necessarily from limited synthetic innovation but due to gaps in observing structural and chemical transformations under environmental conditions. Here, we make a call for a tri-beam operando characterization strategy, integrating synchrotron, neutron, and X-ray free-electron laser (XFEL) techniques into one synergistic experimental framework. Unlike traditional methods providing disconnected snapshots, tri-beam analysis dynamically tracks nanomaterial evolution from atomic-scale changes to structural collapse under near-real-world/quasi-realistic conditions. This holistic approach reveals previously hidden degradation pathways, transient states, and physicochemical thresholds that reshape definitions of material safety. Enhanced by robotic automation, machine learning, and findable, accessible, interoperable, and reusable (FAIR) data principles, our method directly supports Europe’s safe and sustainable by design (SSbD) initiative. We propose embedding tri-beam datasets into regulatory standards, predictive models, and AI-driven screening workflows. Ultimately, tri-beam operando characterization represents a transformative platform for designing resilient, high-performance nanomaterials that meet the environmental and societal demands of the 21st century.
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Sep 2025
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B18-Core EXAFS
I14-Hard X-ray Nanoprobe
I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[25930, 24074, 21441]
Open Access
Abstract: Uranium (U) is a natural radioactive metal and a persistent environmental pollutant. Characterising the influence of arbuscular mycorrhizal fungi (AMF) on U bioaccumulation and partitioning in plants is crucial to understand U soil-to-plant transfer mechanisms. High resolution elemental mapping, spectroscopy and microscopy techniques were conducted on uranyl nitrate dosed Plantago lanceolata roots colonised with Rhizophagus irregularis. U-rich particles accumulated within the root cells, with higher abundance in epidermal and outer cortex cells of mycorrhizal root samples than in non-mycorrhizal roots. Electron microscopy determined two different crystalline U phases, an acicular crystal and a novel rounded aggregate formation, the latter of which was only found within the mycorrhizal root cells. Multiple imaging and spectroscopic techniques enabled the dominant elements with these U biominerals to be determined. Co-localisation between U, phosphorus and oxygen indicated the dominance of U-phosphate biominerals, but metals including calcium and zinc were also found to co-localise. The most dominant U compound was uranyl orthophosphate, likely accompanied by autunite. This study demonstrates alteration in U localisation and U particle morphology within Plantago roots as a direct consequence of AMF colonisation. This knowledge will allow more accurate U food-chain transfer modelling and better assessment of AMF-assisted phytoremediation feasibility.
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Jun 2025
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I08-Scanning X-ray Microscopy beamline (SXM)
I14-Hard X-ray Nanoprobe
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Open Access
Abstract: Advances in X-ray nanoprobe beamlines at synchrotrons across the world present exciting opportunities for rich multimodal imaging of biomineral structures and their formation processes. The combination of techniques provides a sensitive probe of both chemistry and structure, making X-ray nanoprobes an important tool for investigating crystallite growth and orientations, interfaces and assembly of building blocks into hierarchical structures. A discussion of these capabilities is presented with reference to recent examples using a range of nanoprobe imaging techniques for investigating enamel structure, as well as coccolith properties. Key opportunities for the use of X-ray nanoprobes lie in exploiting the penetrating power and coherence properties of synchrotron X-rays in order to image in situ processes or apply coherent diffractive imaging techniques to obtain higher resolutions. To this end initial results demonstrating the observation of calcium phosphate mineralisation, in a liquid environment, using nano-X-ray fluorescence mapping are presented, and the role of X-ray dose and beam induced effects is considered. Finally novel results from tomographic ptychography imaging of a Mytilus Edulis mussel shell calcite prisms are discussed, where the segmentation of the phase density into organic and mineral content give insights into the mechanisms underlying mineral prism formation and the role of the organic matrix in biomineralisation.
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May 2025
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I14-Hard X-ray Nanoprobe
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Diamond Proposal Number(s):
[28688]
Open Access
Abstract: Understanding the interactions between metal-based nanoparticles and biological systems in complex environments (e.g., the human body, soils, and marine settings) remains challenging, especially at the single-cell and nanoscale levels. Capturing the dynamics of these interactions, such as metal distribution, nanoparticle growth, or degradation, in their native state (in vivo) is particularly difficult. Here, we demonstrate the direct measurement of iron content in hydrated, magnetite-biomineralizing magnetotactic bacteria using synchrotron-based nanobeam–scanning X-ray fluorescence microscopy combined with a liquid cell environment. In addition to X-ray fluorescence imaging, we collected iron chemical speciation information from individual bacteria in liquid using X-ray absorption spectroscopy. To follow biomineralization in situ, we developed a microfluidic device to track magnetite nanoparticle formation over several hours under the X-ray beam. This approach highlights the potential of X-ray fluorescence microscopy in liquid cell setups to provide elemental and chemical insights into biological processes at the single-cell level. Combining X-ray nanobeam techniques with liquid cell devices will enable more “on-chip” experiments on metals in biological contexts to be conducted at the synchrotron.
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Mar 2025
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I18-Microfocus Spectroscopy
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Camilo A.
Mesa
,
Michael
Sachs
,
Ernest
Pastor
,
Nicolas
Gauriot
,
Alice J.
Merryweather
,
Miguel A.
Gomez-Gonzalez
,
Konstantin
Ignatyev
,
Sixto
Gimenez
,
Akshay
Rao
,
James R.
Durrant
,
Raj
Pandya
Diamond Proposal Number(s):
[30381]
Open Access
Abstract: Photo(electro)catalysts use sunlight to drive chemical reactions such as water splitting. A major factor limiting photocatalyst development is physicochemical heterogeneity which leads to spatially dependent reactivity. To link structure and function in such systems, simultaneous probing of the electrochemical environment at microscopic length scales and a broad range of timescales (ns to s) is required. Here, we address this challenge by developing and applying in-situ (optical) microscopies to map and correlate local electrochemical activity, with hole lifetimes, oxygen vacancy concentrations and photoelectrode crystal structure. Using this multi-modal approach, we study prototypical hematite (α-Fe2O3) photoelectrodes. We demonstrate that regions of α-Fe2O3, adjacent to microstructural cracks have a better photoelectrochemical response and reduced back electron recombination due to an optimal oxygen vacancy concentration, with the film thickness and extended light exposure also influencing local activity. Our work highlights the importance of microscopic mapping to understand activity, in even seemingly homogeneous photoelectrodes.
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May 2024
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I14-Hard X-ray Nanoprobe
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Huayun
Shi
,
Oliver W. L.
Carter
,
Fortuna
Ponte
,
Cinzia
Imberti
,
Miguel A.
Gomez-Gonzalez
,
Fernando
Cacho-Nerin
,
Paul D.
Quinn
,
Julia E.
Parker
,
Emilia
Sicilia
,
Huaiyi
Huang
,
Peter J.
Sadler
Diamond Proposal Number(s):
[27852]
Open Access
Abstract: The novel hetero-dinuclear complex trans,trans,trans-[PtIV(py)2(N3)2(OH)(μ-OOCCH2CH2CONHCH2-bpyMe)IrIII(ppy)2]Cl (Pt-Ir), exhibits charge transfer between the acceptor photochemotherapeutic Pt(IV) (Pt-OH) and donor photodynamic Ir(III) (Ir-NH2) fragments. It is stable in the dark, but undergoes photodecomposition more rapidly than the Pt(IV) parent complex (Pt-OH) to generate Pt(II) species, an azidyl radical and 1O2. The Ir(III)* excited state, formed after irradiation, can oxidise NADH to NAD⋅ radicals and NAD+. Pt-Ir is highly photocytotoxic towards cancer cells with a high photocytotoxicity index upon irradiation with blue light (465 nm, 4.8 mW/cm2), even with short light-exposure times (10–60 min). In contrast, the mononuclear Pt-OH and Ir-NH2 subunits and their simple mixture are much less potent. Cellular Pt accumulation was higher for Pt-Ir compared to Pt-OH. Irradiation of Pt-Ir in cancer cells damages nuclei and releases chromosomes. Synchrotron-XRF revealed ca. 4× higher levels of intracellular platinum compared to iridium in Pt-Ir treated cells under dark conditions. Luminescent Pt-Ir distributes over the whole cell and generates ROS and 1O2 within 1 h of irradiation. Iridium localises strongly in small compartments, suggestive of complex cleavage and excretion via recycling vesicles (e.g. lysosomes). The combination of PDT and PACT motifs in one molecule, provides Pt-Ir with a novel strategy for multimodal phototherapy.
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Apr 2024
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I14-Hard X-ray Nanoprobe
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Lucas Atila
Bernardes Marcal
,
Nils
Lamers
,
Susanna
Hammarberg
,
Zhaojun
Zhang
,
Huaiyu
Chen
,
Dmitry
Dzhigaev
,
Miguel
Gomez-Gonzalez
,
Julia
Parker
,
Alexander
Bjorling
,
Anders
Mikkelsen
,
Jesper
Wallentin
Diamond Proposal Number(s):
[25924]
Open Access
Abstract: Over the last years metal halide perovskites have demonstrated remarkable potential for integration in light emitting devices. Heterostructures allow for tunable bandgap depending on the local anion composition, crucial for optoelectronic devices, but local structural effects of anion exchange in single crystals is not fully understood. Here, we investigate how the anion exchange of CsPbBr3 nanowires fully and locally exposed to HCl vapor affects the local crystal structure, using nanofocused x-rays. We study the nanoscale composition and crystal structure as function of HCl exposure time and demonstrate the correlation of anion exchange with changes in the lattice parameter. The local composition was measured by x-ray fluorescence and x-ray diffraction, with general agreement of both methods but with much less variation using latter. The heterostructured nanowires exhibit unintentional gradients in composition, both axially and radially. Ferroelastic domains are observed for all HCl exposure times, and the magnitude of the lattice tilt decreases for higher Cl concentrations.
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Mar 2024
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