Intracellular concentration map of magnesium in whole cells by combined use of X-ray fluorescence microscopy and atomic force microscopy

We report a novel experimental approach to derive quantitative concentration map of light elements in whole cells by combining two complementary nano-probe methods: X-ray fluorescence microscopy (XRFM) and atomic force microscopy (AFM). The concentration is derived by normalizing point-by-point the elemental (here Mg) spatial distribution obtained by XRFM, by the thickness measured using AFM. The considerable difference between the elemental distribution and the concentration maps indicates that this procedure is essential to obtain reliable information on the role and function of elements in whole cells.

► X-ray fluorescence and AFM have been measured on the same de-hydrated whole cells.
► The element distribution has been normalized point-by-point by the cell thickness.
► The element (Mg) concentration map has been obtained on a whole cell.
► The element concentration map is quite different from the distribution map.
► Higher Mg concentration is found in the cell periphery.