Mummy Skin

A skin sample from a South‐Andean mummy dating back from the XIth century was analyzed using time‐of‐flight secondary ion mass spectrometry imaging using cluster primary ion beams (cluster‐TOF‐SIMS). For the first time on a mummy, skin dermis and epidermis could be chemically differentiated using mass spectrometry imaging. Differences in amino‐acid composition between keratin and collagen, the two major proteins of skin tissue, could indeed be exploited. A surprising lipid composition of hypodermis was also revealed and seems to result from fatty acids damage by bacteria. Using cluster‐TOF‐SIMS imaging skills, traces of bio‐mineralization could be identified at the micrometer scale, especially formation of calcium phosphate at the skin surface. Mineral deposits at the surface were characterized using both scanning electron microscopy (SEM) in combination with energy‐dispersive X‐ray spectroscopy and mass spectrometry imaging. The stratigraphy of such a sample was revealed for the fi...

The crucial barrier properties of the stratum corneum (SC) depend critically on the design and integrity of its layered molecular structure. However, analysis methods capable of spatially resolved molecular characterization of the SC are scarce and fraught with severe limitations, e.g., regarding molecular specificity or spatial resolution. Here, we used 3D time-of-flight secondary ion mass spectrometry to characterize the spatial distribution of skin lipids in corneocyte multilayer squams obtained by tape stripping. Depth profiles of specific skin lipids display an oscillatory behavior that is consistent with successive monitoring of individual lipid and corneocyte layers of the SC structure. Whereas the most common skin lipids, i.e., ceramides, C24:0 and C26:0 fatty acids and cholesteryl sulfate, are similarly organized, a distinct 3D distribution was observed for cholesteryl oleate, suggesting a different localization of cholesteryl esters compared to the lipid matrix separating ...

The preservation process of soft tissues in an archeological context is mainly unknown because they occur only in truly exceptional situations. The Cova des Pas is a Bronze Age site in Minorca where the special conditions enabled the preservation of some soft tissues associated with 66 individuals. This finding allows the study of the preservation process that took place by means of the analysis of the histological and chemical characteristics of the tissues. Our results show that the preservation mechanism was the adipocere, because the fatty acids profile shows higher concentration of saturated than unsaturated fatty acids. The evidence indicates that the kind of funerary ritual and the environmental conditions favored this preservation.

The permeability of skin to nanoparticles of titanium dioxide (TiO 2) used in sunscreens as a reflector of the UV wavelengths of sunlight, was examined using nuclear microscopy techniques. Special attention was given to the permeation characteristics of these nanoparticles across the outer layers of skin, the stratum corneum, in healthy and psoriatic skin condition. Aspects that may influence the interpretation of results such as sample preparation difficulties and skin condition were focused. Sample preparation can damage the integrity of the corneocyte layers inducing unwanted artefacts that may bias the evaluation of results. Irradiation conditions may also introduce distortions in the labile structures of human skin. Skin condition, such as loss of corneocyte cohesion occurring in psoriasis also influence the permeation profile of the nanoparticles. Weighing and accounting for these features in the examination of skin by nuclear microscopy is crucial to accurately assess the TiO 2 nanoparticles permeation depth.

In spite of extensive regulation to limit exposure, nickel remains the main cause of contact allergy in the general population. More detailed knowledge on the skin uptake of haptens is required. So far, no method exists for the visualization of clinically relevant haptens and their distribution in the skin. To show, in terms of a proof of concept, that imaging mass spectrometry [time of flight secondary ion mass spectrometry (ToF-SIMS)] can be applied for investigation of the penetration and distribution of nickel in human skin. Full-thickness human skin obtained from breast reduction surgery was exposed to nickel sulfate (5% in deionized water) for 24 h in Franz-type diffusion cells. Biopsies were obtained from nickel-treated samples and control (deionized water). The tissue was sliced, and analysed with ToF-SIMS, generating high-resolution images of ion distribution in the epidermis and upper dermis. The skin layers could be discerned from the ToF-SIMS data, particularly on the ba...

A skin sample from a South-Andean mummy dating back from the XI th century was analyzed using time-of-flight secondary ion mass spectrometry imaging using cluster primary ion beams (cluster-TOF-SIMS). For the first time on a mummy, skin dermis and epidermis could be chemically differentiated using mass spectrometry imaging. Differences in amino-acid composition between keratin and collagen, the two major proteins of skin tissue, could indeed be exploited. A surprising lipid composition of hypodermis was also revealed and seems to result from fatty acids damage by bacteria. Using cluster-TOF-SIMS imaging skills, traces of bio-mineralization could be identified at the micrometer scale, especially formation of calcium phosphate at the skin surface. Mineral deposits at the surface were characterized using both scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy and mass spectrometry imaging. The stratigraphy of such a sample was revealed for the first time using this technique. More precise molecular maps were also recorded at higher spatial resolution, below 1 mm. This was achieved using a non-bunched mode of the primary ion source, while keeping intact the mass resolution thanks to a delayed extraction of the secondary ions. Details from biological structure as can be seen on SEM images are observable on chemical maps at this sub-micrometer scale. Thus, this work illustrates the interesting possibilities of chemical imaging by cluster-TOF-SIMS concerning ancient biological tissues.

Skin protects the body from pathogens and degradation. Mummified skin in particular is extremely resistant to decomposition. External influences or the action of micro-organisms, however, can degrade the connective tissue and lay the subjacent tissue open. To determine the ...

We performed proteomics analysis on four skin and one muscle tissue samples taken from three ancient Egyptian mummies of the first intermediate period, approximately 4200 years old. The mummies were first dated by radiocarbon dating of the accompany-\break ing textiles, and morphologically examined by scanning electron microscopy of additional skin samples. Proteins were extracted, separated on SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) gels, and in-gel digested with trypsin. The resulting peptides were analysed using nanoflow high-performance liquid chromatography-mass spectrometry. We identified a total of 230 unique proteins from the five samples, which consisted of 132 unique protein identifications. We found a large number of collagens, which was confirmed by our microscopy data, and is in agreement with previous studies showing that collagens are very long-lived. As expected, we also found a large number of keratins. We identified numerous proteins th...

The scientific investigation of "Hair after Death" is one of the very few areas of human science where we can be forgiven for being a little…duplicitous, as hair fibers are "as dead" on the most active and alive scalp as they are after we have long-since passed away. By the time the hair follicle forms the keratinized hair shaft within its follicular factory, the fiber itself is effectively "dead." Biologists even refer to this process as "terminal differentiation" to hammer home the point .

Surface preparation with gas cluster ion beam (GCIB) sputtering was performed on paint cross-sections, which belong to the collection of the Royal Institute for Cultural Heritage (KIKIRPA), Brussels, Belgium. Superficial cleaning of cross sections with residual embedding resin surface contamination was studied with different sputtering times in order to obtain a gain in the spectral and imaging mode. Sputtering was made directly through the Time-of-Flight-SIMS apparatus. It was thus demonstrated that GCIB sputtering for a short period was very efficient for the superficial decontamination of cultural heritage cross-sections without visible damage on the valuable samples. The GCIB sputtering time and dose can be highly decreased when combined with a monoatomic argon ion beam preparation techniques such as the ion milling systems.

The state of conservation/degradation of mummy human remains, can be inferred from their biochemical composition, as well as the secondary structures of proteins. Infrared microscopy is a very appropriate technique for addressing such issues. In this study, skin leg of an Egyptian mummy, was collected and prepared by microtomy, and was analysed using an infrared imager (Spectrum TM Spotlight) and using synchrotron infrared microscopy. Complementary analyses at both large scale and size close to the diffraction limit help tremendously for understanding the state of degradation. The external layer of mummy skin appears to be more preserved as evidenced by the presence of characteristic biological vibrational features (in particular amide bands) in spectra collected within this region. Adipocere and calcium oxalate are the main degradation products identified in the mummy skin. The origin of the degradation process is not yet fully understood. #

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging using cluster primary ion beams is used for the identification of the pigments in the painting of Rebecca and Eliezer at the Well by Nicolas Poussin. The combination of the high mass resolution of the technique with a sub-micrometer spatial resolution offered by a delayed extraction of the secondary ions, together with the possibility to simultaneously identifying both minerals and organics, has proved to be the method of choice for the study of the stratigraphy of a paint cross section. The chemical compositions of small grains are shown with the help of a thorough processing of the data, with images of specific ions, mass spectra extracted from small regions of interest, and profiles drawn along the different painting layers.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is quickly becoming a critical tool in the field of art conservation. This technique provides high-resolution spatial maps of both inorganic and organic components located within cross-sectional samples collected from works of art. With recent advances in surface analysis, ToF-SIMS can now be used to identify specific amino acids present in protein-containing materials as well as fatty acids in drying oils. For example, the detection of the ion fragment associated with the amino acid hydroxyproline can be used to confirm the use of animal glue in a paint sample. As an analytical technique, ToF-SIMS avoids the need for derivatization/silylation reagents, with no interference by the presence of pigments. Furthermore, the layered systems that are often encountered in historical paint samples remain intact throughout the analytical procedure. This allows for the colocalization of organic and inorganic species in specific layers (e.g. egg yolk paint atop a glue ground). Because of this ability to localize the analytical signal to approximately 6 μm or less, the mass spectral information can be used to produce mass-resolved and spatially-resolve images which can be correlated to previous studies of the same samples. In this study, ToF-SIMS was used to analyze a paint cross section obtained from a painting attributed to Raphael, and another from a painting by the Sienese artist Matteo di Giovanni.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is quickly becoming a critical tool in the field of art conservation. This technique provides high-resolution spatial maps of both inorganic and organic components located within cross-sectional samples collected from works of art. With recent advances in surface analysis, ToF-SIMS can now be used to identify specific amino acids present in protein-containing materials as well as fatty acids in drying oils. For example, the detection of the ion fragment associated with the amino acid hydroxyproline can be used to confirm the use of animal glue in a paint sample. As an analytical technique, ToF-SIMS avoids the need for derivatization/silylation reagents, with no interference by the presence of pigments. Furthermore, the layered systems that are often encountered in historical paint samples remain intact throughout the analytical procedure. This allows for the colocalization of organic and inorganic species in specific layers (e.g. egg yolk paint atop a glue ground). Because of this ability to localize the analytical signal to approximately 6 μm or less, the mass spectral information can be used to produce mass-resolved and spatially-resolve images which can be correlated to previous studies of the same samples. In this study, ToF-SIMS was used to analyze a paint cross section obtained from a painting attributed to Raphael, and another from a painting by the Sienese artist Matteo di Giovanni.

Raman spectroscopy is able to provide novel information non-destructively in the analysis of ancient skin tissue samples. The technique is well-suited to partially desiccated or wet samples of skin, which may have been subjected to varying degrees of degradation, depending on the burial environment. Suitable selection of wavelength of excitation and use of a Raman microscope offer a means of accessing information from small samples, which may be required for study afterwards using destructive analytical methods. From comparisons with the Raman spectra of healthy and diseased contemporary skin specimens, it is possible to discover whether the skin preservation has been natural or assisted by chemicals used in mummification processes. Such information is of importance in archaeological conservation and can shed light on historical practices. In this study will be presented the results from Raman spectroscopic analysis of the skin of the 5200-year-old ''iceman'' of the Alps and, skin and nail samples from the mediaeval Qilakitsoq ice-mummies (500-year-old) and skin from the hotdesert Chiribaya Mummies (1000-year-old). #