Submicron hard X-ray fluorescence imaging of synthetic elements.

Area of Science:

• Biomedical imaging
• Nuclear chemistry
• Cell biology

Background:

• Synchrotron-based X-ray fluorescence microscopy (XFM) is a powerful tool for elemental analysis.
• Hard X-rays focused to sub-micron spots enable high-resolution elemental quantification and mapping.
• XFM also facilitates microspectroscopic measurements like X-ray absorption near edge structure (XANES).

Purpose of the Study:

• To utilize XFM for imaging and quantifying plutonium in individual rat pheochromocytoma (PC12) cells.
• To investigate the intracellular localization of plutonium (242Pu) and co-localized elements.
• To determine the minimum detection limits for plutonium using XFM.

Main Methods:

• X-ray fluorescence microscopy (XFM) with hard X-rays.
• Quantification of plutonium at the L(3) or L(2)-edge.
• Simultaneous elemental mapping of plutonium, thorium, and essential elements.
• Use of copper electron microscopy grids to prevent gold interference.

Main Results:

• Plutonium was primarily localized in the cytoplasm of PC12 cells.
• The cell nucleus showed high concentrations of phosphorus and zinc, excluding plutonium.
• The minimum detection limit for plutonium was 1.4 fg per cell (2.9×10(-20) moles μm(-2)).
• Strontium interference with plutonium detection via L(α) emission was noted.

Conclusions:

• XFM is effective for mapping and quantifying transuranic elements like plutonium in biological cells.
• Plutonium exhibits distinct intracellular compartmentalization, avoiding the nucleus in PC12 cells under experimental conditions.
• The established detection limits are comparable to other XFM techniques, highlighting its utility in radioisotope research.