Surface Functionalization Methods to Enhance Bioconjugation in Metal-Labeled Polystyrene Particles.

Area of Science:

• Nanotechnology and Materials Science
• Bioconjugation Chemistry
• Analytical Chemistry and Immunoassays

Background:

• Lanthanide-encoded polystyrene particles are suitable for mass cytometry immunoassays.
• Previous limitations included the inability to conjugate biomolecules to particle surfaces.
• Need for improved methods for surface functionalization and bioconjugation.

Purpose of the Study:

• To develop post-functionalization strategies for lanthanide-encoded particles.
• To enable covalent attachment of proteins for enhanced immunoassay applications.
• To create particles with improved bioconjugation capacity for mass cytometry.

Main Methods:

• Synthesized particles with surface carboxyl groups (-COOH) using poly(N-vinylpyrrolidone) stabilizer.
• Grafted poly(methacrylic acid) (PMAA) onto particles via seeded emulsion polymerization.
• Grew a poly(glycidyl methacrylate) (PGMA) shell onto particles using seeded emulsion polymerization.

Main Results:

• Carboxyl-functionalized particles showed minimal improvement in bioconjugation.
• The PGMA shell enabled extensive NeutrAvidin conjugation (approx. 7 × 10^5 events/particle) with low non-specific binding.
• Mass cytometry confirmed high binding capacity and stability of the functionalized particles without affecting lanthanide distribution.

Conclusions:

• Seeded emulsion polymerization to grow a PGMA shell is a highly effective method for post-functionalizing lanthanide-encoded particles.
• The epoxide-rich PGMA shell facilitates robust protein conjugation for mass cytometry applications.
• These functionalized particles represent a significant advancement for highly multiplexed bioassays.