Amine-Modified Polystyrene Latex Beads (0.2–0.5 µm, 2.5% w/v) – Catalog #B2025659

Amine-Modified Polystyrene Latex Beads (Catalog #B2025659) are uniformly sized, spherical particles (200–500 nm diameter) with amine functional groups covalently bound to the polystyrene surface. Supplied as a 2.5% w/v suspension in 5 mL, these beads offer a ready-to-use platform for flow cytometry, immunoassays, protein immobilization, and diagnostic applications.

Scientific Overview

Polystyrene latex microspheres in the 200–500 nm size range occupy an important niche between smaller nanoparticles and larger microbeads. This size provides moderate surface area, good particle dispersity, and efficient binding kinetics in solution-phase immunoassays. The 2.5% w/v formulation is a standard concentration that balances particle availability with ease of handling and resuspension.

Amine surface chemistry enables facile covalent coupling to proteins and antibodies using EDC/NHS or other amine-reactive cross-linkers. In flow cytometry, these beads serve both as compensator beads (for instrument standardization) and as platforms for multiplex assays where different bead subsets are distinguished by size and internal fluorescence and each subset carries a different capture antibody.

Key applications include:

• Flow cytometry compensation and standardization beads
• Multiplex bead-based immunoassays (e.g., Luminex platforms)
• ELISA and sandwich immunoassay platforms
• Fluorescence-based protein labeling and detection
• Cell-free in vitro diagnostic assays
• Biomarker enrichment and detection

Usage & Handling Guidance

Store at 2–8°C. The 2.5% w/v concentration provides a convenient working stock; vortex gently before each use to resuspend settled beads. Do not sonicate aggressively, as this can damage the surface or reduce the monodispersity.

• Protein coupling: Wash beads 2–3 times in PBS to exchange the storage buffer. Incubate with protein and EDC/NHS at a molar ratio optimized for your ligand. Typical coupling times are 2–4 hours at room temperature or overnight at 4°C.
• Dilution: For low-concentration assays, dilute beads in PBS or Tris-buffered saline (TBS) just before use. Extreme dilution may promote aggregation; prepare fresh working dilutions daily.
• Coupling efficiency: Request a COA/TDS for lot-specific binding data, or perform a test coupling with your target protein to optimize conditions.
• Blocking: After coupling, block free amine groups with glycine (1 M, pH 8) for 20–30 minutes to reduce nonspecific binding.

What You Get

• 5 mL of amine-modified polystyrene latex beads (200–500 nm), 2.5% w/v suspension
• Monodisperse, uniformly sized particles with reactive amine surface
• Convenient, ready-to-use concentration for standard assay applications
• Optimal size for flow cytometry and moderate-throughput immunoassays
• For research use only (RUO)

Why Researchers Choose It

• Moderate size (200–500 nm) balances surface area with assay compatibility
• 2.5% w/v concentration is ideal for flow cytometry and multiplex assays
• Amine surface enables rapid, straightforward protein immobilization
• Biologically inert polystyrene minimizes nonspecific protein binding
• Wide compatibility with commercial flow cytometers and multiplex platforms (Luminex, etc.)

Frequently Asked Questions (FAQ)

• What is the exact particle concentration in this 2.5% w/v suspension?
  Concentration varies by particle size and density. Request a COA/TDS for the particles-per-mL specification for your lot.
• Can I use these beads in a Luminex multiplex assay?
  Yes, if the bead size and concentration are within the instrument's specifications. Consult the instrument manual and request a COA confirming Luminex compatibility.
• How do I prepare beads for coupling?
  Wash 2–3 times in PBS by centrifuging and resuspending. Discard the supernatant and proceed with EDC/NHS coupling in the desired buffer.
• What is the maximum protein loading?
  Depends on the protein size and the cross-linker stoichiometry. Perform a titration with your target protein to find the saturation point, or request lot-specific binding data from us.
• Can I couple nucleic acids to these beads?
  Yes. Use amine-to-carboxyl coupling if your DNA or RNA has 5' or 3' phosphate or carboxyl groups, or use amine-reactive linkers.

References

• Xianyu Y, Dong Y, Wang Z, Xu Z, Huang R, Chen Y. Broad-Range Magnetic Relaxation Switching Bioassays Using Click Chemistry-Mediated Assembly of Polystyrene Beads and Magnetic Nanoparticles. ACS Sens. 2019;4(7):1942-1949.
• Chen H, Yang F, Yin G, Song P. Nanomaterial-assisted determination of osteosarcoma by antibody-osteopontin-aptamer sandwich ELISA. Biotechnol Appl Biochem. 2022;69(4):1646-1652.
• Kim S, Pyo HB, Ko SH, Ah CS, Kim A, Kim WJ. Fabrication of anionic sulfate-functionalized nanoparticles as an immunosensor by protein immobilization. Langmuir. 2010;26(10):7355-64.