Development of a single-cell X-ray fluorescence flow cytometer.

Area of Science:

• Analytical Chemistry
• Biotechnology
• Cell Biology

Background:

• Measuring metal content in individual cells is challenging with existing analytical methods.
• Understanding intracellular metal heterogeneity is crucial for various biological processes.

Purpose of the Study:

• To develop and demonstrate an X-ray fluorescence flow cytometer for single-cell metal content analysis.
• To investigate the population heterogeneity of metal concentrations in different cell types.

Main Methods:

• Cells were loaded into capillaries using capillary action or pressure.
• Single cells were transported past a focused X-ray beam for analysis.
• X-ray fluorescence was employed to quantify the mass of metal within each cell.

Main Results:

• The developed flow cytometer successfully measured metal composition in bovine red blood cells, mouse fibroblasts, and yeast cells.
• Population heterogeneity in metal concentrations (µM to mM range) was observed across fL sample volumes.
• An average measurement frequency of approximately 4 cells per minute was achieved.

Conclusions:

• The X-ray fluorescence flow cytometer provides a novel method for direct, single-cell metal quantification.
• The findings highlight significant and previously unobserved metal distribution heterogeneity in biological cell populations.
• The technology offers potential for improved sensitivity and further applications in cellular metal analysis.