Highly sensitive spatially resolved elemental and chemical X-ray analysis
"The ESRF - the European Synchrotron Radiation Facility – produces X-rays 100 billion times brighter than the X-rays used in hospitals. Thanks to the brilliance and quality of its X-rays, the ESRF functions like a "super-microscope". It provides unrivalled opportunities for scientists in the exploration of materials." (from the ESRF homepage)
Environmental science and nano-particles
"Environmental science is an interdisciplinary scientific field that combines physical, biological, and chemical sciences for the understanding of environmental systems. Its main objectives are the study of environmental pollution processes, natural resources management, and the effects of global climate change.
Main anthropogenic activities contributing to the release of metals and metalloids in our environment include metal mining and smelting, metallurgical industries, use of fertilizers and soil amendments in high-production agriculture, and land disposal techniques for municipal/solid wastes. Contrary to organic pollutants, metals and metalloids could not be degraded and have long residence times in soils. In addition to the problems caused by traditional metallic pollutants (Cd, Cr, Hg, Zn…), now we need to take into account the use and subsequent widespread in the environment of emerging contaminants such as Engineered Nanomaterials (ENM). These materials contain nanoscale structures (from 1 to 100 nm) that confer them performance characteristics, mainly high reactivity and conductivity due to their high surface/area ratios. Among ENMs, metallic and metal oxide nanoparticles (NPs) such as TiO2, Ag, CuO, CeO2, Fe xO y, and ZnO are being used in a wide range of products and applications such as: paints, food packaging, textiles, electronic devices or pesticides. The National Science Foundation of the United States estimated a world market for nanotechnology products of 1 trillion US Dollars for 2015. This extensive use of ENMs is most likely leading to an important widespread of NPs in the environment, however quantitative information about these inputs and their ecotoxicological consequences are still scarce.
The presence of metals and metal NPs in soils could compromise their ecological and economical functions and become an environmental and human health risk if these pollutants are transferred from soils to the food chain through plants.
It is well recognized that, in terms of availability and toxicity in the environment, metal speciation is more important than total concentration. In the case of plants, metal speciation determines the distribution of an element in plant tissues and ultimately the various mechanisms of toxicity and detoxification. The chemical form and distribution of a metal in the plant are also important to determine the risk assessment derived from animal/human consumption. In this sense, the development of non-destructive microspectroscopic techniques, utilized after careful sample preparation, as available at ID21, is of special interest to study the fate of metals in the environment."
Says Dr. Hiram Castillo, Scientist at beamline ID21 of the ESRF and one of the world leading experts in this field.
Structural characterization of engineered materials at the ESRF is primarily achieved by employing techniques based on scattering and/or tomography in the hard X-ray regime. The chemical analysis on a (sub-)micron length scale however calls for chemical imaging techniques such as provided by the scanning X-ray microscope of ID21 or ID16B. Often the chemistry of transition metals is investigated, commonly in association with low Z matrix elements (e.g. Si, Al) or low Z elements in functional groups and counter-ions (e.g. S, P, Cl, K). Two-dimensional scanning µXRF combined with point-by-point µXANES in the tender X-ray regime under high vacuum allows for probing the electronic structure of transition metals (K-edge for period 4, L-edges for period 5 and M-edges for period 6) while retaining sensitivity to the fluorescence of low Z-elements. Higher energies and smaller beamsize is available on beamline ID16B.
The fluorescence XANES imaging technique developed for the analysis of nano-particles in biological materials provides full chemical imaging in 2D, providing elemental information and XANES spectra for the entire field-of-view with a submicron resolution. This allows for a complete elemental and chemical characterization of electrodes, interfaces and other microstructures over a range of several hundreds of micron.
Synchrotron in life sciences
The synchrotron micro spectroscopy techniques contribute to elucidate the distribution, concentration and chemical state of elements inside tissues and cells. This contribution is not only highly challenging but represents important objectives of modern analytical chemistry and an essential step towards the precise understanding of some cellular pathophysiological or toxicological processes. At the biological level, a great number of trafficking pathways, intracellular transport and compartmentalization can be probed and characteristic molecular signatures can be found. At the biomedical level, targeting of metal-based drugs or medical imaging contrast agents is a necessary step to improve their efficiency. Also, the recent development of nanotechnologies for nanomedecine or for industrial and engineering purposes, raising concerns about their unintentional health and environmental impact, urges the need for efficient analytical tools able to characterize their bio distribution and interaction with living systems