Carboxylate-Modified Polystyrene Latex Beads, >10 µm, 2.5% w/v – Catalog #B2025720

Carboxylate-Modified Polystyrene Latex Beads (Catalog #B2025720) are large, monodisperse polystyrene microspheres functionalized with surface carboxyl groups. At >10 µm diameter supplied at 2.5% w/v in a 5 mL suspension, they combine the practical advantages of large particle size—easy visibility, rapid gravity settling, and convenient manual handling—with a higher bead concentration for applications requiring abundant particles. The large size makes these beads ideal for immunoprecipitation, cell sorting, manual sandwich assays, and any workflow where the researcher needs to observe and manipulate individual beads. Carboxyl groups are readily activated by EDC/carbodiimide chemistry for covalent protein coupling.

Scientific Overview

Carboxylate-modified polystyrene latex beads greater than 10 µm in diameter are among the largest commercially available functional microbeads. Although their surface-area-to-volume ratio is lower than smaller variants (a 15 µm bead has one-third the surface area per unit volume of a 5 µm bead), the large size offers compelling practical advantages: individual beads are visible to the naked eye and under standard light microscopy, particles settle rapidly under gravity without requiring centrifugation, and gentle inversion (not vortexing) is sufficient for resuspension.

Supplied at 2.5% w/v, this variant offers a higher particle concentration than standard lower-concentration suspensions, making it ideal for applications where many beads are needed per reaction or where rapid particle settling is advantageous. The carboxyl surface groups are readily activated by EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide), enabling straightforward covalent coupling of proteins, antibodies, peptides, and other amino-containing molecules via standard carbodiimide chemistry.

Key applications include:

• Immunoprecipitation and co-immunoprecipitation (co-IP) from cell lysates or tissue extracts
• Manual, tube-based immunoassays and affinity-capture workflows
• Single-bead or limited-bead-number applications where bead visibility is essential
• Bead-based cell sorting and enrichment from complex samples
• Substrate for creating large magnetic beads when coated with magnetic particles
• Educational demonstrations and student laboratory experiments

Usage & Handling Guidance

Store at 2–8°C and protect from excessive agitation. Before use, gently invert the tube 3–5 times to evenly distribute beads. The large particle size and high concentration ensure reliable, bubble-free resuspension without vortexing or sonication.

• Coupling procedure: Activate beads with EDC (10–40 mM in pH 5–6 coupling buffer) for 15–30 minutes with gentle inversion. Add protein (10–100 µg/mL) and incubate 1–4 hours at room temperature or overnight at 4°C.
• Bead recovery by gravity: After incubation, allow beads to settle for 5–10 minutes, then carefully remove supernatant by pipetting. No centrifugation is required.
• Washing: Resuspend settled beads in wash buffer (PBS + 0.1% Tween-20 or equivalent), allow to settle, and remove supernatant. Repeat 2–3 times.
• Protein loading estimation: Large beads at >10 µm typically accommodate 100–500 protein molecules depending on protein size and coupling efficiency. This is sufficient for most affinity-capture and immunoprecipitation workflows.
• Blocking non-specific binding: Incubate coupled beads with BSA (2–5% in PBS) for 30 minutes with gentle mixing, then wash, to block the hydrophobic polystyrene surface.

What You Get

• 5 mL of carboxylate-modified polystyrene latex beads at >10 µm diameter
• Supplied at 2.5% w/v concentration for high particle density
• Reactive carboxyl groups suitable for EDC/NHS conjugation
• Large size for maximum ease of handling and visualization
• For research use only (RUO)

Why Researchers Choose It

• Large beads are individually visible and easily tracked throughout assays
• Rapid gravity settling (5–10 minutes) eliminates need for centrifugation in most workflows
• Higher concentration (2.5% w/v) provides abundant particles for high-bead-number applications
• Gentle resuspension (inversion only); no risk of aggregation or damage from vortexing
• Proven chemistry and reliability for manual, low-to-moderate-throughput assays

Frequently Asked Questions (FAQ)

• What is the difference between this product (B2025720) and B202646?
  Both are large (>10 µm) beads with the same carboxyl-modified polystyrene chemistry. B2025720 is supplied at 2.5% w/v (higher bead concentration), while B202646 is supplied at a lower standard concentration. Choose B2025720 if you need more beads per unit volume.
• How many beads per milliliter at 2.5% w/v?
  A 2.5% w/v suspension of large (15 µm) beads contains roughly 10^10 to 10^11 particles per mL, depending on the exact bead size distribution. Request a COA for lot-specific particle concentration.
• Can I couple multiple proteins sequentially to the same beads?
  Theoretically yes, but practically not recommended. The large surface area of one large bead is typically saturated by a single protein species. For multiplex assays, use smaller beads or separate beads for each protein.
• Are these beads suitable for automated assay platforms?
  These large beads are best suited for manual, low-throughput workflows. For automated high-throughput screening (e.g., plate readers, liquid handlers), use smaller beads (1–3 µm) designed for microplate compatibility.
• How long do protein-coupled beads remain stable?
  Protein-coupled beads are stable for several months at 2–8°C, or longer at −20°C in a cryoprotectant such as 50% glycerol. Include an antimicrobial preservative (0.02% sodium azide or Proclin) to prevent microbial contamination during extended storage.
• What dilution should I use for assays?
  Start with the stock 2.5% w/v suspension and dilute as needed (typically 1:10 to 1:100 depending on the assay). Dilution in PBS or assay buffer maintains bead stability and prevents clumping.
• Can I use these beads for magnetic separation?
  These are non-magnetic polystyrene beads. However, they can be coated with or attached to magnetic particles to create large magnetic beads, which are very convenient for automated magnetic separators.

References

• Molina-Bolívar JA, Galisteo-González F, Hidalgo-Alvarez R. Particle enhanced immunoassays stabilized by hydration forces: a comparative study between IgG and F(ab)2 immunoreactivity. J Immunol Methods. 1998;211(1-2):87-95.
• Fortin M, Hugo P. Surface antigen detection with non-fluorescent, antibody-coated microbeads: an alternative method compatible with conventional fluorochrome-based labeling. Cytometry. 1999;36(1):27-35.
• Kamyshny A, Feldman A, Baszkin A, Boissonnade MM, Rosilio V V, Magdassi S. Chemically Modified Glucose Oxidase with Enhanced Hydrophobicity: Adsorption at Polystyrene, Silica, and Silica Coated by Lipid Monolayers. J Colloid Interface Sci. 1999;218(1):300-308.