Biological applications of X-ray fluorescence microscopy: exploring the subcellular topography and speciation of transition metals.

Synchrotron X-ray fluorescence microscopy (SXRF) is a microanalytical technique for the quantitative mapping of elemental distributions. Among currently available imaging modalities, SXRF is the only technique that is compatible with fully hydrated biological samples such as whole cells or tissue sections, while simultaneously offering trace element sensitivity and submicron spatial resolution. Combined with the ability to provide information regarding the oxidation state and coordination environment of metal cations, SXRF is ideally suited to study the intracellular distribution and speciation of trace elements, toxic heavy metals and therapeutic or diagnostic metal complexes.