X-ray microanalysis and mapping: measuring uptake and intracellular distribution of labeled molecules

X-ray microanalysis is a useful technique for elemental analysis of tissues and cells. This technique utilizes x-rays generated in ultra-thin cryosections of tissue by the electron beam in an electron microscope. The x-rays are characteristic of the various elements, and can be used to measure quantitatively the elemental distribution at subcellular levels. An important application of this x-ray microanalysis and mapping technique is the study of uptake and intracellular distribution of molecules containing an element not normally present in the tissue. It is useful for tissues and samples in which the cell population is not homogeneous. Mapping permits elemental distributions to be measured throughout the sample, not just at selected sites. Maps created are not only for the element of interest but also for other specified elements present. Using an x-ray imaging system and cisplatin as a model, we have been able to demonstrate the feasibility of studying the cellular and subcellular distribution of cisplatin, a molecule containing platinum atom.