XAS imaging

X-ray absorption spectroscopy (XAS) can probe intact tissues, in principle non-destructively, and obtain biochemical information about a target element wherever it occurs within complex systems. Examples of samples which might be studied include cell cultures, tissue fragments, or even intact (small) organisms. The technique has previously lacked the sensitivity to answer most questions in this area, but recent developments in synchrotron light technology mean that physiologically relevant levels are now feasible in many cases.
Two fundamentally different types of measurement can be made - bulk XAS where a relatively large X-ray beam interrogates the whole sample, and XAS imaging where a microscopic beam is used to build up images or maps of the different chemical species of a particular element. Bulk XAS has the best sensitivity, but XAS imaging has obvious advantages in developing a biochemical understanding of biometals in whole tissues.