ORCID Profile
0000-0002-8034-5513
Current Organisations
Georg-August-Universität Göttingen
,
Argonne National Laboratory
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Inorganic Chemistry | Bioinorganic Chemistry | Chemical Spectroscopy | Biological And Medical Chemistry | Molecular Medicine | Bioinorganic Chemistry | Analytical Spectrometry
Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Biological Sciences | Treatments (e.g. chemicals, antibiotics) | Chemical sciences | Expanding Knowledge in the Medical and Health Sciences |
Publisher: MDPI AG
Date: 21-05-2013
DOI: 10.3390/NU5051734
Publisher: Wiley
Date: 22-12-2016
Publisher: American Chemical Society (ACS)
Date: 27-04-2010
DOI: 10.1021/CB1000263
Abstract: Growing evidence points toward a very dynamic role for metals in biology. This suggests that physiological circumstance may mandate metal ion redistribution among ligands. This work addresses a critical need for technology that detects, identifies, and measures the metal-containing components of complex biological matrixes. We describe a direct, user-friendly approach for identifying and quantifying metal-protein adducts in complex s les using native- or SDS-PAGE, blotting, and rapid synchrotron X-ray fluorescence mapping with micro-XANES (X-ray absorption near-edge structure) of entire blots. The identification and quantification of each metal bound to a protein spot has been demonstrated, and the technique has been applied in two exemplary cases. In the first, the speciation of the in vitro binding of exogenous chromium to blood serum proteins was influenced markedly by both the oxidation state of chromium exposed to the serum proteins and the treatment conditions, which is of relevance to the biochemistry of Cr dietary supplements. In the second case, in vivo changes in endogenous metal speciation were examined to probe the influence of oxygen depletion on iron speciation in Shewanella oneidensis.
Publisher: Proceedings of the National Academy of Sciences
Date: 09-02-2015
Abstract: X-ray fluorescence microscopy provides unparalleled sensitivity for measuring the distribution of trace elements in many-micrometer-thick specimens, whereas ptychography offers a path to the imaging of weakly fluorescing biological ultrastructure at beyond-focusing-optic resolution. We demonstrate here for the first time, to our knowledge, the combination of fluorescence and ptychography for imaging frozen-hydrated specimens at cryogenic temperatures, with excellent structural and chemical preservation. This combined approach will have significant impact on studies of the intracellular localization of nanocomposites with attached therapeutic or diagnostic agents, help elucidate the roles of trace metals in cell development, and further the study of diseases where trace metal misregulation is suspected (including neurodegenerative diseases).
Publisher: The Optical Society
Date: 23-02-2015
DOI: 10.1364/OE.23.005438
Publisher: Proceedings of the National Academy of Sciences
Date: 20-10-2009
Abstract: While the role of microorganisms as main drivers of metal mobility and mineral formation under Earth surface conditions is now widely accepted, the formation of secondary gold (Au) is commonly attributed to abiotic processes. Here we report that the biomineralization of Au nanoparticles in the metallophillic bacterium Cupriavidus metallidurans CH34 is the result of Au-regulated gene expression leading to the energy-dependent reductive precipitation of toxic Au(III)-complexes. C. metallidurans , which forms biofilms on Au grains, rapidly accumulates Au(III)-complexes from solution. Bulk and microbeam synchrotron X-ray analyses revealed that cellular Au accumulation is coupled to the formation of Au(I)-S complexes. This process promotes Au toxicity and C. metallidurans reacts by inducing oxidative stress and metal resistances gene clusters (including a Au-specific operon) to promote cellular defense. As a result, Au detoxification is mediated by a combination of efflux, reduction, and possibly methylation of Au-complexes, leading to the formation of Au(I)-C-compounds and nanoparticulate Au 0 . Similar particles were observed in bacterial biofilms on Au grains, suggesting that bacteria actively contribute to the formation of Au grains in surface environments. The recognition of specific genetic responses to Au opens the way for the development of bioexploration and bioprocessing tools.
Publisher: Wiley
Date: 16-02-2017
Abstract: [Rh III (*Cp)Cl(X,Y)] n + complexes {X, Y = Cl, PTA, n = 0 ( 2 ) X, Y = en, n = 1 ( 3 , Cl – salt 4 , PF 6 – salt) X, Y = acac, n = 0 ( 5 ) X, Y = cur, n = 0 ( 6 ), where *Cp = pentamethylcyclopentadienato, curH = curcumin PTA = 1,3,5‐triaza‐7‐phosphatricyclo[3.3.1.1]decane en = 1,2‐ethanediamine acac = acetylacetonato = 2,4‐pentanedionato(1–)} were synthesized from [Rh(*Cp)(µ‐Cl)Cl] 2 ( 1 ). While 2 – 5 were inactive against human epithelial A549 lung‐cancer cells in assays of cytotoxicity, and antimetastatic and proapoptotic behaviors, 6 had a cytotoxic activity similar to that of curH over 72 h, but at 24 h in real‐time cell migration assays, it was less active, showing slow release of curH. All complexes underwent ligand‐exchange reactions with biomolecules and cells within the timeframes of the assays (X‐ray absorption spectroscopy). Intracellular elemental distributions (X‐ray fluorescence microscopy) showed that 6 effectively delivered curH to cells, where it was released. Other elemental distributions and caspase activities were consistent with preapoptotic activities. As such, 6 is a promising delivery agent for bioactive ligands, such as curH. However, pure curcumin itself showed a previously unrecognized ability to promote migration of A549 cells at subtoxic concentrations in the presence of endothelial growth factor, which may be a concern for its widespread use as a nutritional supplement and as a potential drug. This aspect warrants further research.
Publisher: Elsevier BV
Date: 04-2005
Publisher: Mary Ann Liebert Inc
Date: 11-2017
Abstract: The inability to unambiguously distinguish the biogenicity of microfossil-like structures in the ancient rock record is a fundamental predicament facing Archean paleobiologists and astrobiologists. Therefore, novel methods for discriminating biological from nonbiological chemistries of microfossil-like structures are of the utmost importance in the search for evidence of early life on Earth. This, too, is important for the search for life on Mars by in situ analyses via rovers or s le return missions for future analysis here on Earth. Here, we report the application of synchrotron X-ray fluorescence imaging of vanadium, within thermally altered organic-walled microfossils of bona fide biological origin. From our data, we demonstrate that vanadium is present within microfossils of undisputable biological origin. It is well known in the organic geochemistry literature that elements such as vanadium are enriched and contained within crude oils, asphalts, and black shales that have been formed by diagenesis of biological organic material. It has been demonstrated that the origin of vanadium is due to the diagenetic alteration of precursor chlorophyll and heme porphyrin pigment compounds from living organisms. We propose that, taken together, microfossil-like morphology, carbonaceous composition, and the presence of vanadium could be used in tandem as a biosignature to ascertain the biogenicity of putative microfossil-like structures. Key Words: Microfossils-Synchrotron micro-X-ray fluorescence-Vanadium-Tetrapyrrole-Biosignature. Astrobiology 17, 1069-1076.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C001499K
Abstract: Herein is described a general s ling protocol that includes culture, differentiation and fixing of cells in their preferred morphology on the one s le substrate (Si(3)N(4)) to enable subsequent erse modern microspectroscopic analyses. The protocol enables unprecedented correlated and complementary information on the intracellular biochemistry of metabolic processes, diseases and their treatment, which offers the opportunity to revolutionize our understanding of cell and tissue biology at a molecular level. The culture of adherent cells onto inexpensive Si(3)N(4) membranes allows microspectroscopic analyses across the electromagnetic spectrum, from hard X-ray fluorescence (both XRF and XANES), through to visible and fluorescence light microscopies, and infrared microspectroscopy without substrate interference. Adherent mammalian cell lines (3T3-L1 adipocytes and H9c2 cardiac myocytes) illustrate the in vitro application of these protocols. The cells adhered strongly to Si(3)N(4) membranes and visually displayed normal proliferative and phenotypic growth more importantly, rapid alcohol fixation of cells did not affect their structural integrity for subsequent analyses.
Publisher: American Chemical Society (ACS)
Date: 02-08-2016
Abstract: Metal toxicity to aquatic organisms depends on the speciation of the metal and its binding to the critical receptor site(s) (biotic ligand) of the organism. The intracellular nature of the biotic ligand for Cu in microalgal cells was investigated using the high elemental sensitivity of microprobe synchrotron radiation X-ray fluorescence (SR-XRF) and X-ray absorption near-edge spectroscopy (XANES). The marine microalgae, Ceratoneis closterium, Phaeodactylum tricornutum, and Tetraselmis sp. were selected based on their varying sensitivities to Cu (72-h 50% population growth inhibitions of 8-47 μg Cu/L). Intracellular Cu in control cells was similar for all three species (2.5-3.2 × 10(-15) g Cu/cell) and increased 4-fold in C. closterium and Tetraselmis sp. when exposed to copper, but was unchanged in P. tricornutum (72-h exposure to 19, 40, and 40 μg Cu/L, respectively). Whole cell microprobe SR-XRF identified endogenous Cu in the central compartment (cytoplasm) of control (unexposed) cells. After Cu exposure, Cu was colocated with organelles/granules dense in P, S, Ca, and Si and this was clearly evident in thin sections of Tetraselmis sp. XANES indicated coexistence of Cu(I) and Cu(II) in control and Cu-exposed cells, with the Cu ligand (e.g., phytochelatin) in P. tricornutum different from that in C. closterium and Tetraselmis sp. This study supports the hypothesis that Cu(II) is reduced to Cu(I) and that polyphosphate bodies and phytochelatins play a significant role in the internalization and detoxification of Cu in marine microalgae.
Publisher: Springer Science and Business Media LLC
Date: 18-06-2020
DOI: 10.1038/S41598-020-66916-8
Abstract: Our future bioeconomy depends on increased utilization of renewable lignocellulosic biomass. Controlling the diffusion of chemicals, such as inorganic ions, within secondary plant cell walls is central to many biomass applications. However, insufficient understanding of intra-cell-wall diffusion within secondary plant cell walls is hindering the advancement of many lignocellulosic biomass applications. In this work, X-ray fluorescence microscopy was used to measure diffusion constants of K + , Cu 2+ , and Cl − diffusing through loblolly pine ( Pinus taeda ) cell wall layers under 70%, 75%, or 80% relative humidity (RH). Results revealed that diffusion constants increased with RH, the larger Cu 2+ diffused more slowly than the K + , and the Cl − diffusion constant was the same as that for the counter cation, indicating cations and anions diffused together to maintain charge neutrality. Comparison with electrical conductivity measurements showed that conductivity is being controlled by ion mobility over these RH. The results further support that intra-cell-wall diffusion of inorganic ions is a Fickian diffusion process occurring through rubbery amorphous polysaccharides, which contradicts previous assertions that intra-cell-wall diffusion is an aqueous process occurring through water pathways. Researchers can now utilize polymer science approaches to engineer the molecular architecture of lignocellulosic biomass to optimize properties for specific end uses.
Publisher: Wiley
Date: 22-12-2016
Abstract: Chromium(III) nutritional supplements are widely consumed for their purported antidiabetic activities. X-ray fluorescence microscopy (XFM) and X-ray absorption near-edge structure (XANES) studies have now shown that non-toxic doses of [Cr3 O(OCOEt)6 (OH2 )3 ](+) (A), a prospective antidiabetic drug that undergoes similar H2 O2 induced oxidation reactions in the blood as other Cr supplements, was also oxidized to carcinogenic Cr(VI) and Cr(V) in living cells. Single adipocytes treated with A had approximately 1 μm large Cr hotspots containing Cr(III) , Cr(V) , and Cr(VI) (primarily Cr(VI) thiolates) species. These results strongly support the hypothesis that the antidiabetic activity of Cr(III) and the carcinogenicity of Cr(VI) compounds arise from similar mechanisms involving highly reactive Cr(VI) and Cr(V) intermediates, and highlight concerns over the safety of Cr(III) nutritional supplements.
Publisher: Oxford University Press (OUP)
Date: 2014
DOI: 10.1039/C4MT00176A
Abstract: The intracellular metal concentration and distribution for Cu, Zn, Fe and Ca were determined by X-ray fluorescence microscopy (XFM) in cultured cortical neurons and were found to be altered in mice lacking APP and APLP2 expression.
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.ARCHORALBIO.2007.04.003
Abstract: The development of analytical techniques for the measurement of trace elements in cellular compartments of developing teeth remains an important methodological issue in dental research. Recent advances in third generation synchrotron facilities have provided high brilliance X-ray sources that can be effectively used to study trace element distributions in small spatial regions with low detection limits. The present study describes for the first time the application of synchrotron radiation induced X-ray emission (SRIXE) in measuring the distribution of zinc and lead in the ameloblasts of developing Wistar rat teeth. Wistar rats were fed a standard rat diet, containing the normal dietary requirements of zinc, ad libitum and exposed to 100 ppm of lead in drinking water. Resin embedded sections of first mandibular molars were analysed using a 13.3 keV incident monochromatic X-ray beam focussed to a 0.2 microm spot. Characteristic X-rays arising from the entire thickness of the s le were measured using an energy dispersive detector for quantitative analysis of elemental concentrations. The results showed that intranuclear concentrations of zinc were greater than levels in the cytoplasm. Furthermore, nuclear and cytoplasmic concentrations of zinc in the maturation stage (742+/-27 and 424+/-25 ppm, respectively) were significantly higher than the zinc levels observed in the nucleus and cytoplasm of presecretory stage ameloblasts (132+/-10 and 109+/-10 ppm, respectively) (p<0.05). A clear lead signal above the background was not detected in the ameloblasts and lead concentrations could only be reliably measured in the developing enamel. Overall, SRIXE was an effective method of studying the spatial distribution of zinc in the cells of developing teeth and offered a unique combination of sub-micron spatial resolution and parts-per-million detection limits (0.8-1 and 0.6-1 ppm for zinc and lead, respectively).
Publisher: Mineralogical Association of Canada
Date: 10-2006
Publisher: American Chemical Society (ACS)
Date: 20-10-2011
DOI: 10.1021/JA206203C
Publisher: Elsevier BV
Date: 04-2011
Publisher: International Union of Crystallography (IUCr)
Date: 07-02-2013
Publisher: Oxford University Press (OUP)
Date: 2017
DOI: 10.1039/C6MT00243A
Abstract: Optical epifluorescence microscopy was used in conjunction with X-ray fluorescence imaging to monitor the stability and intracellular distribution of the luminescent rhenium(i) complex fac-[Re(CO)
Publisher: Wiley
Date: 09-02-2009
DOI: 10.1111/J.1471-4159.2008.05846.X
Abstract: Oxidative stress is associated with the pathology of acute and chronic neurodegenerative disease. We have cloned a human neuroglobin (Nb) construct and over-expressed this protein in cultured human neuronal cells to assess whether Nb ameliorates the cellular response to experimental hypoxia-reoxygenation (H/R) injury. Parental cells transfected with a blank (pDEST40) vector responded to H/R injury with a significant decrease in cellular ATP at 5 and 24 h after insult. This was coupled with increases in the cytosolic Ca(2+), and the transition metals iron (Fe), copper (Cu), and zinc (Zn) within the cell body, as monitored simultaneously using X-ray fluorescence microprobe imaging. Parental cell viability decreased over the same time period with a approximately 4 to 5-fold increase in cell death (maximum approximately 25%) matched by an increase in caspase 3/7 activation (peaking at a 15-fold increase after 24 h) and condensation of beta-actin along axonal processes. Over-expression of Nb inhibited ATP loss and except for significant decreases in the sulfur (S), chlorine (Cl), potassium (K) and Ca(2+) contents, maintained cellular ion homeostasis after H/R insult. This resulted in increased cell viability, significantly diminished caspase activation and maintenance of the beta-actin cytoskeletal structure and receptor-mediated endocytosis. These data indicate that bolstering the cellular content of Nb inhibits neuronal cell dysfunction promoted by H/R insult through multiple protective actions including: (i) maintenance of cellular bioenergetics (ii) inhibition of Ca(2+) influx (iii) a reduction in cellular uptake of Fe, Cu and Zn at the expense of S, Cl and K and (iv) an enhancement of cell viability through inhibiting necrosis and apoptosis.
Publisher: Wiley
Date: 10-2008
DOI: 10.1002/CYTO.A.20616
Abstract: Methods for imaging cellular architecture and ultimately macromolecular complexes and in idual proteins, within a cellular environment, are an important goal for cell and molecular biology. Coherent diffractive imaging (CDI) is a method of lensless imaging that can be applied to any in idual finite object. A diffraction pattern from a single biological structure is recorded and an iterative Fourier transform between real space and reciprocal space is used to reconstruct information about the architecture of the s le to high resolution. As a test system for cellular imaging, we have applied CDI to an important human pathogen, the malaria parasite, Plasmodium falciparum. We have employed a novel CDI approach, known as Fresnel CDI, which uses illumination with a curved incident wavefront, to image red blood cells infected with malaria parasites. We have examined the intrinsic X-ray absorption contrast of these cells and compared them with cells contrasted with heavy metal stains or immunogold labeling. We compare CDI images with data obtained from the same cells using scanning electron microscopy, light microscopy, and scanning X-ray fluorescence microscopy. We show that CDI can offer new information both within and at the surface of complex biological specimens at a spatial resolution of better than 40 nm. and we demonstrate an imaging modality that conveniently combines scanning X-ray fluorescence microscopy with CDI. The data provide independent confirmation of the validity of the coherent diffractive image and demonstrate that CDI offers the potential to become an important and reliable new high-resolution imaging modality for cell biology. CDI can detect features at high resolution within unsectioned cells.
Publisher: American Chemical Society (ACS)
Date: 20-02-2011
DOI: 10.1021/BI101678A
Abstract: Selenium compounds exhibit chemopreventative properties at supranutritional doses, but the efficacy of selenium supplementation in cancer prevention is dependent on the chemical speciation of the selenium supplement and its metabolites. The uptake, speciation, and distribution of the common selenoamino acid supplements, selenomethionine (SeMet) and Se-methylselenocysteine (MeSeCys), in A549 human lung cancer cells were investigated using X-ray absorption and fluorescence spectroscopies. X-ray absorption spectroscopy of bulk cell pellets treated with the selenoamino acids for 24 h showed that while selenium was found exclusively in carbon-bound forms in SeMet-treated cells, a diselenide component was identified in MeSeCys-treated cells in addition to the carbon-bound selenium species. X-ray fluorescence microscopy of single cells showed that selenium accumulated with sulfur in the perinuclear region of SeMet-treated cells after 24 h, but microprobe selenium X-ray absorption near-edge spectroscopy in this region indicated that selenium was carbon-bound rather than sulfur-bound. X-ray absorption and X-ray fluorescence studies both showed that the selenium content of MeSeCys-treated cells was much lower than that of SeMet-treated cells. Selenium was distributed homogeneously throughout the MeSeCys-treated cells.
Publisher: Elsevier BV
Date: 02-2010
Publisher: Springer Science and Business Media LLC
Date: 11-02-2012
DOI: 10.1007/S00775-012-0879-Y
Abstract: Synchrotron radiation induced X-ray emission (SRIXE) spectroscopy was used to map the cellular uptake of the organoselenium-based antioxidant drug ebselen using differentiated ND15 cells as a neuronal model. The cellular SRIXE spectra, acquired using a hard X-ray microprobe beam (12.8-keV), showed a large enhancement of fluorescence at the K(α) line for Se (11.2-keV) following treatment with ebselen (10 μM) at time periods from 60 to 240 min. Drug uptake was quantified and ebselen was shown to induce time-dependent changes in cellular elemental content that were characteristic of oxidative stress with the efflux of K, Cl, and Ca species. The SRIXE cellular Se distribution map revealed that ebselen was predominantly localized to a discreet region of the cell which, by comparison with the K and P elemental maps, is postulated to correspond to the endoplasmic reticulum. On the basis of these findings, it is hypothesized that a major outcome of ebselen redox catalysis is the induction of cellular stress. A mechanism of action of ebselen is proposed that involves the cell responding to drug-induced stress by increasing the expression of antioxidant genes. This hypothesis is supported by the observation that ebselen also regulated the homeostasis of the transition metals Mn, Cu, Fe, and Zn, with increases in transition metal uptake paralleling known induction times for the expression of antioxidant metalloenzymes.
Publisher: International Union of Crystallography (IUCr)
Date: 19-02-2008
Publisher: The Optical Society
Date: 25-07-2012
DOI: 10.1364/OE.20.018287
Publisher: Springer Science and Business Media LLC
Date: 30-04-2011
DOI: 10.1007/S00216-011-4978-3
Abstract: X-ray fluorescence microscopy (XFM) facilitates high-sensitivity quantitative imaging of trace metals at high spatial resolution over large s le areas and can be applied to a erse range of biological s les. Accurate determination of elemental content from recorded spectra requires proper calibration of the XFM instrument under the relevant operating conditions. Here, we describe the manufacture, characterization, and utilization of multi-element thin-film reference foils for use in calibration of XFM measurements of biological and other specimens. We have used these internal standards to assess the two-dimensional distribution of trace metals in a thin tissue section of a rat hippoc us. The data used in this study was acquired at the XFM beamline of the Australian Synchrotron using a new 384-element array detector (Maia) and at beamline 2-ID-E at the Advanced Photon Source. Post-processing of s les by different fixation techniques was investigated, with the conclusion that differences in solvent type and s le handling can significantly alter elemental content. The present study highlights the quantitative capability, high statistical power, and versatility of the XFM technique for mapping trace metals in biological s les, e.g., brain tissue s les in order to help understand neurological processes, especially when implemented in conjunction with a high-performance detector such as Maia.
Publisher: Springer Science and Business Media LLC
Date: 22-11-2008
DOI: 10.1007/S00775-007-0321-Z
Abstract: Quantitative X-ray fluorescence imaging of sections of human teeth revealed an increased concentration of copper and zinc in carious regions of dentine compared with unaffected portions of the tooth. Higher-resolution images provided strong evidence that the copper was transported and localized mainly in the dentinal tubules. While similar levels of zinc were found in these areas and concentrated in the tubules, zinc was also more evident in the hydroxyapatite, and the increase in zinc levels compared with the levels in background (normal) areas was less than that for copper. These results suggest a role for copper and zinc in the formation and progression of dental caries and present a potential point of intervention for treatment.
Publisher: Oxford University Press (OUP)
Date: 2014
DOI: 10.1039/C4MT00088A
Abstract: Se and Cu were colocalised in the kidneys of selenite-fed rats, but there was no evidence of Se–Cu bonding.
Publisher: Wiley
Date: 27-02-2007
DOI: 10.1002/XRS.937
Publisher: American Chemical Society (ACS)
Date: 03-04-2013
DOI: 10.1021/IC300700G
Abstract: Manganese porphyrin-based drugs are potent mimics of the enzyme superoxide dismutase. They exert remarkable efficacy in disease models and are entering clinical trials. Two lead compounds, MnTE-2-PyP(5+) and MnTnHex-2-PyP(5+), have similar catalytic rates, but differ in their alkyl chain substituents (ethyl vs n-hexyl). Herein we demonstrate that these changes in ring substitution impact upon drug intracellular distribution and pharmacological mechanism, with MnTnHex-2-PyP(5+) superior in augmenting menadione toxicity. These findings establish that both catalytic activity and intracellular distribution determine drug action.
Publisher: International Union of Crystallography (IUCr)
Date: 17-03-2009
Start Date: 2014
End Date: 12-2017
Amount: $519,790.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2009
End Date: 12-2014
Amount: $995,000.00
Funder: Australian Research Council
View Funded Activity