Three-dimensional elemental mapping of phosphorus by quantitative electron spectroscopic tomography (QuEST)

Area of Science:

• Materials Science
• Cell Biology
• Nanotechnology

Background:

• Accurate nanoscale elemental distribution is crucial for understanding cellular processes.
• Existing methods lack the resolution and quantification needed for detailed cellular analysis.

Purpose of the Study:

• To develop and validate a novel technique, quantitative electron spectroscopic tomography (QuEST), for 3-D elemental mapping at the nanometer scale.
• To demonstrate QuEST's capability in mapping phosphorus distribution within unstained cellular components.

Main Methods:

• Acquisition of 2-D elemental maps from energy filtering transmission electron microscopy images at various specimen tilt angles.
• Reconstruction of 3-D elemental distributions using an algorithm based on the simultaneous iterative reconstruction technique (SIRT).
• Correction for plural inelastic scattering using unfiltered and zero-loss images, and automated correction for specimen drift and focus changes.

Main Results:

• Successful mapping of phosphorus distribution in unstained, embedded cell sections.
• Accurate quantification of phosphorus content in cellular ribosomes.
• Estimation of nucleic acid density within the cell nucleus.

Conclusions:

• QuEST provides a powerful tool for quantitative 3-D elemental analysis at the nanometer scale.
• The technique achieves high sensitivity, detecting as few as 20 phosphorus atoms in a 2.7 nm voxel.
• QuEST enables detailed investigation of elemental composition in biological systems.