Metal-chelating polymers by anionic ring-opening polymerization and their use in quantitative mass cytometry

Area of Science:

• Polymer Chemistry
• Analytical Chemistry
• Immunology

Background:

• Metal-chelating polymers (MCPs) are crucial for mass cytometry immunoassays, enabling metal isotope carrying and antibody conjugation.
• Optimal polymer characteristics (chain length, backbone, end/pendant groups, synthesis) for MCPs remain undetermined for advanced applications.

Purpose of the Study:

• To synthesize and characterize a novel metal-chelating polymer with controlled molecular weight and orthogonal functionalities.
• To develop a robust method for conjugating these polymers to monoclonal antibodies (mAbs) for multiplexed mass cytometry.

Main Methods:

• Anionic ring-opening polymerization of an activated cyclopropane using 2-furanmethanethiol and a phosphazene base.
• Post-polymerization modification to introduce diethylenetriaminepentaacetic acid (DTPA) chelating groups.
• Characterization using NMR, SEC, TGA, and ITC; antibody conjugation via Diels-Alder and Michael addition reactions.

Main Results:

• Synthesized MCPs with controlled molecular weight (DP=35) and narrow distribution.
• Achieved high metal-binding capacity (49.5 ± 6 Ln(3+) ions/chain) and demonstrated successful conjugation to 10 different mAbs.
• Validated the 10-plex assay in mass cytometry for analyzing 10 cell surface antigens on human peripheral blood cells.

Conclusions:

• The developed MCPs offer precise control over polymer synthesis and efficient metal ion chelation.
• The novel conjugation strategy enables robust antibody labeling for high-plex mass cytometry.
• This platform facilitates sensitive and specific multiplexed analysis of cell surface markers in complex biological samples.