Evaluation of the Elemental Content of a Single Cell using Fast Time- Resolved Analysis (TRA) ICP-MS

Importance of the Topic

Single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS) enables direct measurement of trace elements in individual cells. This capability addresses critical needs in biological and clinical research where sample volumes are limited and bulk analysis masks cell-to-cell variability. By rapidly detecting elemental plumes in under a millisecond, SC-ICP-MS offers high sensitivity and low background, revealing distribution patterns of essential metals that regulate cellular functions.

Objectives and Study Overview

This study evaluated SC-ICP-MS for quantifying magnesium, phosphorus, iron, and zinc in single yeast, green alga, and red blood cells (RBCs). Results were compared to conventional bulk analysis after acid digestion. Key aims were to validate accuracy, assess sample requirements, and explore benefits for metabolism research across fungus, plant, and animal cells.

Methodology and Instrumentation

Cell suspensions of Saccharomyces cerevisiae, Chlamydomonas reinhardtii, and rat RBCs were counted and delivered via a MicroMist glass nebulizer and single-cell introduction system into an Agilent 8900 ICP-QQQ. Fast time-resolved analysis used 0.1 ms integration to capture transient signals. Phosphorus was measured in O2 mass-shift mode (31→47), iron and silicon in H2 on-mass mode, and magnesium and zinc in no-gas mode. Nebulization efficiency was determined using SiO2 nanoparticle standards. Bulk measurements used acid digestion followed by analysis on an Agilent 8800 ICP-QQQ with 100 ms integration.

Main Findings and Discussion

SC-ICP-MS and bulk results agreed closely for yeast and green alga, demonstrating reliable quantification of Mg, P, Fe, and Zn. In RBCs, SC-ICP-MS iron values matched reference mean cell hemoglobin data more accurately than bulk analysis, suggesting reduced interference from lysed cells or serum. Elemental distributions highlighted higher Mg in green alga (photosynthetic requirements), low P and Zn in enucleated RBCs, and elevated Fe in RBCs due to hemoglobin content.

Benefits and Practical Applications

• Minimal sample consumption: requires far fewer cells than bulk methods.
• Enhanced accuracy: avoids contamination from digested matrices.
• Single-cell resolution: reveals heterogeneity in elemental content.
• Rapid analysis: sub-millisecond detection enables high throughput.

Future Trends and Potential Applications

Advances in SC-ICP-MS will likely focus on multiplexed detection of additional biologically relevant elements and isotopes, integration with cell sorting for targeted studies, and coupling with molecular assays to correlate elemental profiles with gene expression. Further miniaturization and automation could extend use to clinical diagnostics, environmental microbiology, and nanotoxicology.

Conclusion

This work demonstrates that fast time-resolved SC-ICP-MS on an Agilent 8900 ICP-QQQ provides accurate, sensitive, and rapid measurement of Mg, P, Fe, and Zn in individual cells. Compared to conventional bulk digestion, the method reduces sample requirements and improves reliability, particularly for iron quantification in RBCs. SC-ICP-MS holds promise for broad applications in biomedical, environmental, and industrial research.

References

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