Zinc in native tissues and cultured cell lines of human prostate studied by SR‐XRF and XANES

During longlasting attempts to understand the aetiology of prostate cancer (CaP) on molecular level, attention has been paid to a unique capability of prostate epithelial cells to accumulate zinc. The latter plays role in a wide range of cellular processes such as the function of immune system, angiogenesis or apoptosis. Zinc has a significant antioxidant function, and its presence in prostate cells is strongly connected with their metabolism. This paper reports on the analysis of zinc concentration and oxidation level in the samples of human CaP tissues and cultured human prostate cell lines such as DU‐145, LNCaP and PC‐3, aided by x‐ray bioimaging. The study was performed by means of synchrotron radiation (SR) techniques. Bioimaging on cellular level, available through the SR x‐ray fluorescence (SR‐XRF) methods, applied to the samples of native prostate tissue, revealed a complexity of structures, while cell culture samples provided areas of homogeneity required for reliable analysis. SR‐XRF enabled us to establish the dependence of zinc concentration upon histological status of tissue (healthy, hyperplastic or cancerous). In‐depth studies of local chemical environment of an x‐ray absorbing zinc atom, including determination of Zn K‐edge position, were possible through the use of x‐ray absorption near edge structure (XANES) analysis. Copyright © 2009 John Wiley & Sons, Ltd.     

Synchrotron‐radiation phase‐contrast imaging of human stomach and gastric cancer: in vitro studies

The electron density resolution of synchrotron‐radiation phase‐contrast imaging (SR‐PCI) is 1000 times higher than that of conventional X‐ray absorption imaging in light elements, through which high‐resolution X‐ray imaging of biological soft tissue can be achieved. For biological soft tissue, SR‐PCI can give better imaging contrast than conventional X‐ray absorption imaging. In this study, human resected stomach and gastric cancer were investigated using in‐line holography and diffraction enhanced imaging at beamline 4W1A of the Beijing Synchrotron Radiation Facility. It was possible to depict gastric pits, measuring 50–70 µm, gastric grooves and tiny blood vessels in the submucosa layer by SR‐PCI. The fine structure of a cancerous ulcer was displayed clearly on imaging the mucosa. The delamination of the gastric wall and infiltration of cancer in the submucosa layer were also demonstrated on cross‐sectional imaging. In conclusion, SR‐PCI can demonstrate the subtle structures of stomach and gastric cancer that cannot be detected by conventional X‐ray absorption imaging, which prompt the X‐ray diagnosis of gastric disease to the level of the gastric pit, and has the potential to provide new methods for the imageology of gastric cancer.     

GE‐MXRF analysis of multilayer films

Polycapillary x‐ray optics (capillary x‐ray lens) is now popular in x‐ray fluorescence (XRF) analysis. Such an x‐ray lens can collect x‐rays emitted from an x‐ray source in a large solid angle and form a very intense x‐ray microbeam which is very convenient for micro x‐ray fluorescence (MXRF) analysis. In this paper, a new method called grazing exit micro x‐ray fluorescence analysis (GE‐MXRF), which combines an x‐ray lens used to form an intense XRF source was developed and applied in multilayer film analysis. Such a method can give the information of film composition, density, and thickness. Through two‐dimensional scan of the film sample, the information of film uniformity can be acquired; meanwhile, this method is also useful in adjusting experiment condition during the film preparation with metal vapor vacuum arc (MEVVA) source ion implantation. Copyright © 2008 John Wiley & Sons, Ltd.     

Total reflection x‐ray fluorescence analysis—a review

Total reflection x‐ray fluorescence analysis (TXRF) is a special energy‐dispersive x‐ray analytical technique extending XRF down to the ultra trace element range. Detection limits of picograms or nanograms per gram levels are reached with x‐ray tube excitation. Using synchrotron radiation as excitation source, femtogram levels are detectable, particularly important for Si wafer surface analysis. TXRF is specially suited for applications in which only a very small amount of sample is available, as only a few micrograms are required for the analysis. In this review, an overview of theoretical principles, advantages, instrumentation, quantification and application is given. Chemical analysis as well as surface analysis including depth profiling and thin‐film characterization is described. Special research results on extension to low‐Z elements, excitation with synchrotron radiation and x‐ray absorption spectroscopy (XAS) for chemical speciation at trace levels are reviewed. Copyright © 2007 John Wiley & Sons, Ltd.     

Characterization of surface carbon films on weathered Japanese roof tiles by soft x‐ray spectroscopy

The effects of weathering on carbon films deposited on Japanese smoked roof tiles were investigated by soft x‐ray absorption and emission spectroscopy using synchrotron radiation. X‐ray absorption measurements revealed that weathering oxidizes the carbon films and that partial carboxy chemical bonding occurs. Incident angle‐dependent x‐ray absorption spectra in the C K region confirmed that the degree of the orientation at the surface of the oxidized carbon films decreases with weathering. However, the take‐off angle‐dependent C K x‐ray emission spectra showed that the orientation of the layered carbon structure is maintained in the bulk portion when weathered. Therefore, it is confirmed that oxidation proceeds from the surface of the carbon films. Weathering degrades and oxidizes the surface carbon films, which causes the metallic silver color to change to darker gray. Copyright © 2005 John Wiley & Sons, Ltd.     

Micro‐beam x‐ray fluorescence analysis of individual particles with correction for absorption effects

A method of correction for absorption effects in micro‐beam x‐ray fluorescence analysis is described. A fast, energy‐dispersive, silicon drift detector (SDD) was used to measure the primary x‐ray beam transmitted through the sample. The absorption factors were calculated using the data acquired with the SDD. The possibility of using the coherently, incoherently and multiple scattered primary radiation for determining the mass of individual particles was examined. The proposed methods were validated with the use of NIST K3089 glass micro‐spheres of known composition. Copyright © 2006 John Wiley & Sons, Ltd.     

Synchrotron radiation refraction topography for characterization of lightweight materials

The employment of synchrotron radiation for refraction topography of materials has considerable advantages over standard x‐ray sources. The much higher beam intensity and the parallel and monochromatic radiation provide faster measurements and better angular and spatial resolution. X‐ray refraction techniques image the inner surface and interface concentration of micro‐structured materials. This effect of x‐ray optics is additional to small‐angle scattering by diffraction, when the scattering objects reach micrometre dimensions. We have developed x‐ray refraction techniques within the last decade in order to meet the growing demands for improved non‐destructive characterization of high‐performance composites, ceramics and other low‐density materials. Sub‐micron particle dimensions, the pore size of ceramics, the crack density distribution and single fibre debonding within damaged composites can be measured and visualized by computer‐generated interface topographs. For this purpose investigations are now being performed at the new hard x‐ray beamline of the Federal Institute for Materials Research and Testing (BAM) at BESSY, Berlin. This BAMline provides monochromatic radiation of photon energies from 5 to 60 keV from a double multilayer and/or a double‐crystal monochromator. A separate instrument is dedicated to the further development and application of synchrotron radiation refraction (SRR) topography. Different from conventional small‐angle scattering cameras with collimating slits and pinholes, scattering angles down to a few seconds of arc are selected by a single‐crystal analyser, similar to a Bonse–Hart diffractometer. A 20 µm spatial resolution of the scattering micro‐structures is achieved by a CCD camera with a fluorescent converter. First SRR topographs of aircraft composites [carbon fibre‐reinforced plastics (CFRP), carbon fibre‐reinforced ceramics (C/C), metal matrix ceramics (MMC)] will be reported. Copyright © 2004 John Wiley & Sons, Ltd.     

Improvements of the low‐energy performance of a micro‐focus x‐ray source for XRF analysis with the SEM

X‐ray Fluorescence (XRF) with a scanning electron microscope (SEM) is a valuable completion of the analytical capabilities of SEMs. Small and compact micro‐focus x‐ray sources are mounted to the microscope chamber, and the x‐ray spectra are monitored with conventional EDS systems. Up to now the x‐ray tubes used for the micro‐focus x‐ray sources are equipped with beryllium windows about 100 µm thick. The poly‐capillary x‐ray lenses have their transmission maximum at photon energies around 10 keV. It drops down in both low‐ and high‐energy ranges. Hence, L‐radiation from an Mo or Rh target will be strongly attenuated, and the excitation of fluorescence in the soft x‐ray range becomes very ineffective. A new micro‐focus x‐ray source was developed. It is characterised by a lower self‐absorption in the tube target, thin beryllium windows and an x‐ray optics having a large distance between its foci and the maximum of transmission at about 5 keV. Thus K line fluorescence of light elements becomes effectively excited by the L‐radiation from Mo or Rh tube targets. The detection limit for sodium oxide in glass was found to be below 1 mass%. Copyright © 2009 John Wiley & Sons, Ltd.     

Distribution and incorporation of zinc in biological calcium phosphates

Human dental calculi are biological calcium phosphates, which consist of an organic phase and an inorganic or mineral phase. In the latter phase, spectrochemical analyses have revealed the presence of several different magnesium and calcium phosphates. As the crystalline structure of the calculus passes through several stages during its allocation in the mouth, special attention is paid to some elements, such as zinc, that can modify the mineralization process. Several in vitro studies relating to the dental calculus mineralization process have been performed so far, but there is a lack of data obtained from biologically synthesized samples. The knowledge of the zinc distribution and incorporation in biological calcium phosphates is of great interest in providing more information about the biological process of calculus formation. In this paper we present surveys of the elemental distribution and incorporation of zinc in human dental calculus, by using a combination of different techniques: x‐ray microfluorescence using synchrotron radiation, scanning electron microscopy and x‐ray absorption spectroscopy. One‐dimensional x‐ray microfluorescence of zinc and magnesium measurement shows that there is a high accumulation of both elements in the sub‐gingival region of the calculus and a strong correlation of their spatial distribution. Experimental Ca/P molar ratios were determined by energy‐dispersive spectroscopy to identify different calcium phosphate phases, the sub‐gingival region being composed of a mixture of highly and poorly calcified phosphates and the supra‐gingival region composed mainly of carbonated hydroxyapatite. Finally, x‐ray absorption measurements were carried out at the zinc K edge on synthetic and biological samples. The Zn—O distance and coordination number of the synthetic samples and the supra‐gingival calculus show that zinc is adsorbed on these structures, whereas in the sub‐gingival samples it is allocated in a cation site. The results are indicative of the active participation of zinc in the calcification process of sub‐gingival calculus. Copyright © 2003 John Wiley & Sons, Ltd.     

The first microbeam synchrotron X‐ray fluorescence beamline at the Siam Photon Laboratory

The first microbeam synchrotron X‐ray fluorescence (µ‐SXRF) beamline using continuous synchrotron radiation from Siam Photon Source has been constructed and commissioned as of August 2011. Utilizing an X‐ray capillary half‐lens allows synchrotron radiation from a 1.4 T bending magnet of the 1.2 GeV electron storage ring to be focused from a few millimeters‐sized beam to a micrometer‐sized beam. This beamline was originally designed for deep X‐ray lithography (DXL) and was one of the first two operational beamlines at this facility. A modification has been carried out to the beamline in order to additionally enable µ‐SXRF and synchrotron X‐ray powder diffraction (SXPD). Modifications included the installation of a new chamber housing a Si(111) crystal to extract 8 keV synchrotron radiation from the white X‐ray beam (for SXPD), a fixed aperture and three gate valves. Two end‐stations incorporating optics and detectors for µ‐SXRF and SXPD have then been installed immediately upstream of the DXL station, with the three techniques sharing available beam time. The µ‐SXRF station utilizes a polycapillary half‐lens for X‐ray focusing. This optic focuses X‐ray white beam from 5 mm × 2 mm (H × V) at the entrance of the lens down to a diameter of 100 µm FWHM measured at a sample position 22 mm (lens focal point) downstream of the lens exit. The end‐station also incorporates an XYZ motorized sample holder with 25 mm travel per axis, a 5× ZEISS microscope objective with 5 mm × 5 mm field of view coupled to a CCD camera looking to the sample, and an AMPTEK single‐element Si (PIN) solid‐state detector for fluorescence detection. A graphic user interface data acquisition program using the LabVIEW platform has also been developed in‐house to generate a series of single‐column data which are compatible with available XRF data‐processing software. Finally, to test the performance of the µ‐SXRF beamline, an elemental surface profile has been obtained for a piece of ancient pottery from the Ban Chiang archaeological site, a UNESCO heritage site. It was found that the newly constructed µ‐SXRF technique was able to clearly distinguish the distribution of different elements on the specimen.     

Distribution of Pb and Zn in slices of human bone by synchrotron µ‐XRF

Synchrotron radiation‐induced micro x‐ray fluorescence analysis (µ‐XRF) at HASYLAB beamline L was used to determine the distribution of Pb and other trace elements in slices of human bone. Using a focused synchrotron x‐ray beam of about 15 µm in diameter it was found that Pb was mostly located at the outer border of the cortical bone in various samples. Ratios of Pb intensities of cortical and trabecular bone varied from 0.027 for hip head to 0.408 for proximal tibia. Additionally Ca, Zn and Sr distributions were simultaneously recorded. A remarkable association between Pb and Zn content could be observed. Copyright © 2004 John Wiley & Sons, Ltd.     

Literature trends in x‐ray emission spectrometry in the period 1990–2000–a review

A quantitative overview is given of the role that x‐ray emission analysis methods, in their various forms, play in the literature for the period from January 1990 to the end of December 2000. The major sources of information were computerized searches through Chemical Abstracts and Web of Science and, specifically for 1998, a manual search through Analytical Abstracts. Areas that are covered in this review pertain to the recent trends in x‐ray emission spectrometry in general and in some specific techniques such as x‐ray fluorescence analysis, synchrotron radiation‐induced and particle‐induced x‐ray emission, total‐reflection and micro‐x‐ray fluorescence analysis. A brief outline of recent developments in the specific fields is given, with emphasis on the various excitation and detection modes, on different application areas and on relative contributions of different countries and languages to the x‐ray emission spectrometry literature. It appears that environmental monitoring and research continue to be particularly important publication fields for x‐ray spectrometry. Copyright © 2003 John Wiley & Sons, Ltd.     

Nanoresolution interface studies in thin films by synchrotron x‐ray diffraction and by using x‐ray waveguide structure

In the last years we performed several measurements with synchrotron radiation of several facilities to reveal interesting interface phenomena on the nanoscale. We used both x‐ray diffraction [1] , [2] (XRD) and spectrometry techniques. In this paper, we briefly summarize the results obtained from diffraction measurements, which lead us to our recent grazing incidence x‐ray fluorescence analysis (GIXRF) and extended x‐ray absorption fine structure (EXAFS) experiments. We show how a combination of experimental methods of GIXRF analysis and EXAFS spectroscopy in fluorescence detection with x‐ray standing waves (XSW) technique was applied for the depth profiling of a‐Si/Co/a‐Si layers with nanometer resolution to monitor the growth of CoSi intermetallic phase. The investigated layers were placed into the waveguide structure formed by two Ta films to increase sensitivity and accuracy of the measurements. Copyright © 2009 John Wiley & Sons, Ltd.     

X‐Tream quality assurance in synchrotron X‐ray microbeam radiation therapy

Microbeam radiation therapy (MRT) is a novel irradiation technique for brain tumours treatment currently under development at the European Synchrotron Radiation Facility in Grenoble, France. The technique is based on the spatial fractionation of a highly brilliant synchrotron X‐ray beam into an array of microbeams using a multi‐slit collimator (MSC). After promising pre‐clinical results, veterinary trials have recently commenced requiring the need for dedicated quality assurance (QA) procedures. The quality of MRT treatment demands reproducible and precise spatial fractionation of the incoming synchrotron beam. The intensity profile of the microbeams must also be quickly and quantitatively characterized prior to each treatment for comparison with that used for input to the dose‐planning calculations. The Centre for Medical Radiation Physics (University of Wollongong, Australia) has developed an X‐ray treatment monitoring system (X‐Tream) which incorporates a high‐spatial‐resolution silicon strip detector (SSD) specifically designed for MRT. In‐air measurements of the horizontal profile of the intrinsic microbeam X‐ray field in order to determine the relative intensity of each microbeam are presented, and the alignment of the MSC is also assessed. The results show that the SSD is able to resolve individual microbeams which therefore provides invaluable QA of the horizontal field size and microbeam number and shape. They also demonstrate that the SSD used in the X‐Tream system is very sensitive to any small misalignment of the MSC. In order to allow as rapid QA as possible, a fast alignment procedure of the SSD based on X‐ray imaging with a low‐intensity low‐energy beam has been developed and is presented in this publication.     

Study of an archeological opaque red glass bead from China by XRD,XRF, and XANES

As a kind of rare archeological founding in China, red decorative beads (300–400 ad ) were discovered in Leijiaping, Badong County, Hubei, China. For the first time, this paper reports an advanced structural analysis of glass beads using micro synchrotron X‐ray near‐edge absorption spectroscopy. The results show that in spite of being opaque, the red bead is made of glass containing two forms of copper atoms, including 0⁺ and 1⁺. In combination with X‐ray diffraction results, it is advised that the mechanism of red coloration mainly comes from metallic copper. This paper indicates that micro synchrotron X‐ray near‐edge absorption spectroscopy is an outstanding and advanced technology to study ancient glass objects with nondestructive mode. Copyright © 2012 John Wiley & Sons, Ltd.     

Radiobiological features of the anti‐cancer strategies involving synchrotron X‐rays

Synchrotrons are opening new paths in innovative anti‐cancer radiotherapy strategies. Indeed, the fluence of X‐rays induced by synchrotrons is so high (10⁶ times higher than standard medical irradiators) that it enables the production of X‐ray beams tunable in energy (monochromatic beams) and in size (micrometric beams). Monochromatic synchrotron X‐ray beams theoretically permit photoactivate high‐Z elements to be introduced in or close to tumours in order to increase the yield of damage by enhanced energy photoabsorption. This is notably the case of attempts with iodinated contrast agents used in tumour imaging (the computed tomography therapy approach) and with platinated agents used in chemotherapy (the PAT‐Plat approach). Micrometric synchrotron X‐ray beams theoretically permit very high radiation doses to accumulate in tumours by using arrays of parallel microplanar beams that spare the surrounding tissues (the microbeam radiation therapy approach). These anti‐cancer applications of synchrotron radiation have been developed at the European Synchrotron Radiation Facility to be applied to glioma, one of the tumour tissues most refractory to standard treatments. In the present paper the molecular and cellular mechanisms involved in these three approaches are reviewed, in the context of recent advances in radiobiology. Furthermore, by considering the unavoidable biases, an attempt to propose a comparison of the different results obtained in preclinical trials dealing with rats bearing tumours is given.     

Micro‐synchrotron x‐ray fluorescence of the metal distribution in a black spruce tree stem: evidence for radial mobility

Micro‐synchrotron radiation x‐ray fluorescence has been used to examine the metal distribution across an entire black spruce stem. The results show the individual elements to be transported and sequestered in different ways so that apparent elemental mobility within the stem changes from element to element. The results suggest that a detailed knowledge of the behavior of each element is required before pollution chronologies can be inferred from dendroanalysis. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of organic ligands on Pb absorption and speciation changes in Arabidopsis as determined by micro X‐ray fluorescence and X‐ray absorption near‐edge structure analysis

Pb can pass through the food chain via plants and threaten human health, which has attracted widespread attention. Changes in Pb speciation affect its bioavailability in soils and water. However, whether organic ligands can change the uptake and mobility of Pb in plants and increase or decrease Pb bioavailability remains uncertain. To reveal the roles of organic and inorganic Pb in Pb metabolism in plants, the localization and speciation changes of Pb in Arabidopsis thaliana plants grown in organic and inorganic Pb were characterized by synchrotron radiation micro X‐ray fluorescence and X‐ray absorption near‐edge structure, respectively. These results demonstrated that Arabidopsis absorbed more Pb from Pb(NO₃)₂ than Pb(CH₃COO)₂ at the same exposure concentration. A higher percentage of Pb‐citrate was found in Arabidopsis exposed to inorganic Pb solution, which suggested that Pb‐citrate was the main complex for root‐to‐shoot transportation in Arabidopsis exposed to inorganic Pb solutions. Pb complexed with the organic ligand CH₃COO^? significantly inhibited primary root growth and lateral root development, while, at the same time, Pb was blocked by root hairs, which represented another way to reduce Pb absorption and protect the plant from biotoxicity.     

Elemental micro-imaging and quantification of human substantia nigra using synchrotron radiation based x-ray fluorescence--in relation to Parkinson's disease

Synchrotron radiation based x-ray fluorescence (SRXRF) was applied to the quantitative evaluation of elemental changes in substantia nigra pars compacta (SNc) in Parkinson's disease (PD) in the framework of a study on the role of chemical elements in the pathophysiology of PD. The analysis was carried out for dopaminergic nerve cells and extraneuronal spaces. The mass fractions of P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb were determined. The application of standard samples developed especially for the determination of elemental mass fractions in thin tissue sections using the SRXRF technique is presented. Two-dimensional maps of elemental distribution show that the location of nerve cells in SNc sections is precisely visualized by the high levels of most elements. It was found that statistically significant differences between control and PD neurons are observed for S (p = 0.04), Cl (p = 0.02), Ca (p = 0.08), Fe (p = 0.04) and Zn (p = 0.04). The mass fractions of P (p = 0.08), S (p = 0.07), Cl (p = 0.04), Zn (p = 0.08) and Rb (p = 0.08) in areas outside the nerve cell bodies differed significantly between PD and control groups. A clear cluster separation between the PD nerve cells and neurons representing the control group was noticed. It was found that Cl, Fe, Ca and Zn are the most significant elements in the general discrimination between PD nerve cells and the control. The comparison between the extraneuronal spaces showed that Cl, Fe and Cu differentiate the PD and control group the most. The evident contribution of chemical elements to the pathophysiology of PD was shown.     

Fish otolith trace element maps: new approaches with synchrotron microbeam x‐ray fluorescence

Otoliths, the carbonate earstones of fishes, take up minor and trace amounts of elements as they accrete through a fish's life. We apply synchrotron microbeam x‐ray fluorescence methods to establish a breakthrough in high‐resolution, simultaneous area mapping of multiple trace elements in otoliths, with spatial resolution down to 20 µm and trace element detection down into the part per million range for multiple elements. Concentration maps of Ca, Sr, Zn and, for the first time, Ba, Mn, and Se are obtained simultaneously. Combinations of these elemental maps provide new insights into the environmental history of fishes and their lifetime movements, illustrated by several case studies. This method helps pave the way toward improved spatial analysis of otolith microchemistry. Copyright © 2007 John Wiley & Sons, Ltd.