Apoferritin Nanoparticle-Based Mass Tags: A Novel Metal Tagging Strategy for Mass Cytometry.

Area of Science:

• Biotechnology
• Nanotechnology
• Immunology

Background:

• Mass cytometry (MC) offers high-dimensional single-cell analysis but faces limitations in sensitivity and current mass tag technology.
• Existing MC tags can suffer from higher background noise and lower sensitivity, impacting assay performance.

Purpose of the Study:

• To develop a novel metal tagging strategy for MC using apoferritin nanoparticles (AFNPs).
• To improve MC sensitivity, reduce non-specific binding, and enable chelator-independent, multiplexed assays.

Main Methods:

• AFNPs were prepared by loading rare-earth metals and phosphate ions into apoferritin nanocages.
• Antibodies were conjugated to AFNPs using a maleimide linker (NHS-PEG22-MAL).
• The developed AFNP tags were tested for sensitivity, non-specific binding, and performance in MC assays using human PBMCs.

Main Results:

• AFNP tags demonstrated significantly higher sensitivity (over twofold increase) compared to metal-chelating polymer (MCP) tags.
• AFNP tags exhibited low non-specific binding, leading to reduced background signals in MC assays.
• Multiparameter analysis of PBMCs showed good agreement between the new MC assay and traditional flow cytometry (FC).

Conclusions:

• A novel, chelator-independent metal tagging strategy using AFNPs was successfully developed for MC.
• The AFNP tags offer enhanced sensitivity, low non-specific binding, and multiplexing capabilities.
• This advancement is expected to significantly contribute to the further development and application of mass cytometry.