The complexity and heterogeneity of artistic materials make their chemical characterization uneas... more The complexity and heterogeneity of artistic materials make their chemical characterization uneasy. Micro-imaging techniques are commonly applied to attain full 2D descriptions of fragments cross-sections. At the European Synchrotron Radiation Facility (ESRF), Grenoble, France, the ID21 beamline is primarily designed for scanning X-ray microscopy. Since 2004, it also hosts a Fourier Transform Infrared (FTIR) end-station. The combined access (fig. 1) on a single beamline to both X-ray and FTIR micro spectroscopies has become a main asset in the characterization of very complex heterogeneous samples at the micron scale in several research fields, such as Cultural Heritage Sciences with a particular focus on paintings. At the ID21 beamline, the X-ray microscope is devoted to micro X-ray fluorescence and micro X-ray Absorption Near-Edge Spectroscopy (XANES) in the tender X-ray domain (2-9 keV). Therefore, it is very well suited to reveal the chemical state of pigments with a very high l...
Transthyretin (TTR) amyloid fibrils are the main component of the amyloid deposits occurring in F... more Transthyretin (TTR) amyloid fibrils are the main component of the amyloid deposits occurring in Familial Amyloidotic Polyneuropathy patients. This is 1 of 20 human proteins leading to protein aggregation disorders such as Alzheimer's and Creutzfeldt-Jakob diseases. The structural details concerning the association of the protein molecules are essential for a better understanding of the disease and consequently the design of new strategies for diagnosis and therapeutics. Disulfide bonds are frequently considered essential for the stability of protein aggregates and since in the TTR monomers there is one cysteine residue, it is important to determine unambiguously the redox state of sulfur present in the fibrils. In this work we used x-ray spectroscopy to further characterize TTR amyloid fibrils. The sulfur K-edge absorption spectra for the wild type and some amyloidogenic TTR variants in the soluble and fibrillar forms were analyzed. Whereas in the soluble proteins the thiol group from cysteine (R-SH) and the thioether group from methionine (R-S-CH(3)) are the most abundant forms, in the TTR fibrils there is a significant oxidation of sulfur to the sulfonate form in the cysteine residue and a partial oxidation of sulfur to sulfoxide in the methionine residues. Further interpretation of the data reveals that there are no disulfide bridges in the fibrillar samples and suggest conformational changes in the TTR molecule, namely in strand A and/or in its vicinity, upon fibril formation.
X-ray imaging in differential interference contrast (DIC) with submicrometer optical resolution w... more X-ray imaging in differential interference contrast (DIC) with submicrometer optical resolution was performed by using a twin zone plate (TZP) setup generating focal spots closely spaced within the TZP spatial resolution of 160 nm. Optical path differences introduced by the sample are recorded by a CCD camera in a standard full-field imaging and by an aperture photodiode in a standard scanning transmission x-ray microscope. Applying this x-ray DIC technique, we demonstrate for both the full-field imaging and scanning x-ray microscope methods a drastic increase in image contrast (approximately 20x) for a low-absorbing specimen, similar to the Nomarski DIC method for visible-light microscopy.
Biochimica et Biophysica Acta (BBA) - General Subjects, 2003
New information about calcium status in human scalp hair shaft, deduced from X-ray micro-fluoresc... more New information about calcium status in human scalp hair shaft, deduced from X-ray micro-fluorescence imaging, including its distribution over the hair section, the existence of one or several binding-types and its variation between people, is presented. The existence of two different calcium types is inferred. The first one corresponds to atoms (or ions) easily removable by hydrochloric acid, located in the cortex (granules), in the cuticle zone and also in the core of the medulla, which can reasonably be identified as calcium soaps. The second type consists of non-easily removable calcium atoms (or ions) that are located in the medulla wall, probably also in the cuticle, and rather uniformly in the cortex; these calcium atoms may be involved in Ca(2+)-binding proteins, and their concentration is fairly constant from one subject to another. In addition to its nonuniform distribution across the hair section, the second striking feature of the first type calcium content is its high variability from one subject to another, by up to a factor 10. We expect this information to be useful for analyzing in more detail the relationship between hair calcium and environmental and medical factors.
ABSTRACT Micro-beam x-ray absorption fine structure spectroscopy was used to investigate rutile T... more ABSTRACT Micro-beam x-ray absorption fine structure spectroscopy was used to investigate rutile TiO2 nanoparticles internalized into gastrointestinal cells during their crossing of a gut model barrier. Nanoparticles diluted in culture medium tend to accumulate in cells after 48 h exposure; however, no spectral differences arise between particles in cellular and in acellular environments, as corroborated by quantitative analysis. This finding establishes that no modification of the lattice properties of the nanoparticles occurs upon interaction with the barrier. These measurements demonstrate the possibility of interrogating nanoparticles in situ within cells, suggesting a way to investigate their fate when incorporated in biological hosts.
The complexity and heterogeneity of artistic materials make their chemical characterization uneas... more The complexity and heterogeneity of artistic materials make their chemical characterization uneasy. Micro-imaging techniques are commonly applied to attain full 2D descriptions of fragments cross-sections. At the European Synchrotron Radiation Facility (ESRF), Grenoble, France, the ID21 beamline is primarily designed for scanning X-ray microscopy. Since 2004, it also hosts a Fourier Transform Infrared (FTIR) end-station. The combined access (fig. 1) on a single beamline to both X-ray and FTIR micro spectroscopies has become a main asset in the characterization of very complex heterogeneous samples at the micron scale in several research fields, such as Cultural Heritage Sciences with a particular focus on paintings. At the ID21 beamline, the X-ray microscope is devoted to micro X-ray fluorescence and micro X-ray Absorption Near-Edge Spectroscopy (XANES) in the tender X-ray domain (2-9 keV). Therefore, it is very well suited to reveal the chemical state of pigments with a very high l...
Transthyretin (TTR) amyloid fibrils are the main component of the amyloid deposits occurring in F... more Transthyretin (TTR) amyloid fibrils are the main component of the amyloid deposits occurring in Familial Amyloidotic Polyneuropathy patients. This is 1 of 20 human proteins leading to protein aggregation disorders such as Alzheimer's and Creutzfeldt-Jakob diseases. The structural details concerning the association of the protein molecules are essential for a better understanding of the disease and consequently the design of new strategies for diagnosis and therapeutics. Disulfide bonds are frequently considered essential for the stability of protein aggregates and since in the TTR monomers there is one cysteine residue, it is important to determine unambiguously the redox state of sulfur present in the fibrils. In this work we used x-ray spectroscopy to further characterize TTR amyloid fibrils. The sulfur K-edge absorption spectra for the wild type and some amyloidogenic TTR variants in the soluble and fibrillar forms were analyzed. Whereas in the soluble proteins the thiol group from cysteine (R-SH) and the thioether group from methionine (R-S-CH(3)) are the most abundant forms, in the TTR fibrils there is a significant oxidation of sulfur to the sulfonate form in the cysteine residue and a partial oxidation of sulfur to sulfoxide in the methionine residues. Further interpretation of the data reveals that there are no disulfide bridges in the fibrillar samples and suggest conformational changes in the TTR molecule, namely in strand A and/or in its vicinity, upon fibril formation.
X-ray imaging in differential interference contrast (DIC) with submicrometer optical resolution w... more X-ray imaging in differential interference contrast (DIC) with submicrometer optical resolution was performed by using a twin zone plate (TZP) setup generating focal spots closely spaced within the TZP spatial resolution of 160 nm. Optical path differences introduced by the sample are recorded by a CCD camera in a standard full-field imaging and by an aperture photodiode in a standard scanning transmission x-ray microscope. Applying this x-ray DIC technique, we demonstrate for both the full-field imaging and scanning x-ray microscope methods a drastic increase in image contrast (approximately 20x) for a low-absorbing specimen, similar to the Nomarski DIC method for visible-light microscopy.
Biochimica et Biophysica Acta (BBA) - General Subjects, 2003
New information about calcium status in human scalp hair shaft, deduced from X-ray micro-fluoresc... more New information about calcium status in human scalp hair shaft, deduced from X-ray micro-fluorescence imaging, including its distribution over the hair section, the existence of one or several binding-types and its variation between people, is presented. The existence of two different calcium types is inferred. The first one corresponds to atoms (or ions) easily removable by hydrochloric acid, located in the cortex (granules), in the cuticle zone and also in the core of the medulla, which can reasonably be identified as calcium soaps. The second type consists of non-easily removable calcium atoms (or ions) that are located in the medulla wall, probably also in the cuticle, and rather uniformly in the cortex; these calcium atoms may be involved in Ca(2+)-binding proteins, and their concentration is fairly constant from one subject to another. In addition to its nonuniform distribution across the hair section, the second striking feature of the first type calcium content is its high variability from one subject to another, by up to a factor 10. We expect this information to be useful for analyzing in more detail the relationship between hair calcium and environmental and medical factors.
ABSTRACT Micro-beam x-ray absorption fine structure spectroscopy was used to investigate rutile T... more ABSTRACT Micro-beam x-ray absorption fine structure spectroscopy was used to investigate rutile TiO2 nanoparticles internalized into gastrointestinal cells during their crossing of a gut model barrier. Nanoparticles diluted in culture medium tend to accumulate in cells after 48 h exposure; however, no spectral differences arise between particles in cellular and in acellular environments, as corroborated by quantitative analysis. This finding establishes that no modification of the lattice properties of the nanoparticles occurs upon interaction with the barrier. These measurements demonstrate the possibility of interrogating nanoparticles in situ within cells, suggesting a way to investigate their fate when incorporated in biological hosts.
Uploads
Papers by B. Fayard