Quantitative imaging of metals in tissues.

Metals and other trace elements play an important role in many physiological processes in all biological systems. Characterization of precise metal concentrations, their spatial distribution, and chemical speciation in individual cells and cell compartments will provide much needed information to explore the metallome in health and disease. Synchrotron-based X-ray fluorescent microscopy (SXRF) is the ideal tool to quantitatively measure trace elements with high sensitivity at high resolution. SXRF is based on the intrinsic fluorescent properties of each element and is therefore element specific. Recent advances in synchrotron technology and optimization of sample preparation have made it possible to image metals in mammalian tissue with submicron resolution. In combination with correlative methods, SXRF can now, for example, determine the amount and oxidation state of trace elements in intra-cellular compartments and identify cell-specific changes in the metal ion content during development or disease progression.