HiSur Carboxyl Beads

What it means: Magnetic Beads are polymer- or silica-matrix particles with embedded iron oxide cores that respond to an external magnetic field. They can be pulled out of solution rapidly using a permanent magnet or magnetic separation rack.

Why it matters:

• Enables hands-free wash and separation steps — no centrifuge or filter column needed.
• Particle size (50 nm–4.5 µm range) determines separation speed, surface area per mg, and suspension stability.
• Iron oxide content (18–80%) governs how fast beads respond to a magnet — higher content = faster separation.
• Surface functional groups determine which coupling chemistry and biomolecule classes can be immobilized.

How to interpret here: This product is a Magnetic Bead format. Select the size and surface chemistry variant that matches your conjugation strategy and magnetic separation setup. Check the specification sheet for magnetic content and recommended separator.

Tip: Always resuspend by bath sonication before use — magnetic beads settle during storage and may not be fully redispersed by vortexing alone.

What it means: HiSur is the high-surface-area bead series (1 µm) engineered with a porous polymer coating that provides approximately three times the surface area per bead compared to standard MonoMag 1 µm beads. This translates directly into higher functional group density and binding capacity.

Why it matters:

• ~3× surface area per bead versus MonoMag = higher antibody or protein loading per unit volume of beads.
• Enables assay development with lower total bead concentrations while maintaining equivalent capture capacity.
• ~40% iron content provides fast magnetic separation comparable to larger monodisperse formats.
• Suitable for high-sensitivity immunoassay development and diagnostic manufacturing requiring maximum ligand density.

How to interpret here: This is a HiSur series product (1 µm, single size). Select HiSur when maximum binding capacity per bead volume is the priority. Compare performance with SuperMag or MonoMag formats to confirm which best meets your binding capacity and separation speed balance.

Tip: HiSur beads are benchmarked against Sera-Mag Speedbeads in streptavidin and protein G formats, showing comparable or superior capacity in published assay comparisons.

What it means: Carboxyl (–COOH) surface groups are reactive functional groups that enable covalent coupling to primary amines (–NH₂) via EDC/NHS activation chemistry. The carboxyl group itself is not reactive without activation — it requires EDC (with optional Sulfo-NHS) to form an active NHS ester intermediate.

Why it matters:

• Enables coupling to lysine residues or N-terminus of antibodies and proteins — the most commonly used bioconjugation approach.
• Gives a stable, covalent amide bond between the particle surface and the target biomolecule.
• Activation step (EDC ± NHS) must be performed in amine-free buffer (pH 5.5–6.0 for EDC, pH 7.2–7.5 for coupling).
• Low non-specific binding after blocking with BSA or similar makes carboxyl beads well-suited for quantitative assays.

How to interpret here: This product has Carboxyl surface chemistry. Coupling requires EDC/NHS activation as described in the protocol (see Documents). Avoid Tris, glycine, or other amine-containing buffers during activation and coupling steps — they inactivate the NHS ester.

Tip: Add Sulfo-NHS along with EDC to stabilize the activated intermediate. This significantly improves coupling efficiency at neutral pH and longer incubation times.

What it means: Particle Size refers to the mean hydrodynamic diameter of the particle in suspension. Available sizes: 1 um.

Why it matters:

• Bead size affects surface area, suspension stability, and magnetic separation speed.
• Smaller particles have higher surface area per mg — more binding sites per weight of material.
• Larger particles settle faster under gravity and separate faster with a magnet.
• Select size based on your magnetic separation speed requirements, surface area needs, and assay geometry.

How to interpret here: This product is available in 1 um. Smaller sizes have more surface area per mg; larger sizes separate faster with a magnet.

Tip: Particle size is measured by DLS (dynamic light scattering) and represents the hydrodynamic diameter, which includes surface coating — actual iron core size is smaller as shown in TEM measurements in the specification sheet.

What it means: Activated (Ready-to-conjugate) means the particle surface carries a reactive functional group (carboxyl, amine, NHS ester, maleimide, or azide) that is ready for coupling to your chosen biomolecule. A conjugation reaction step is required before the beads can capture targets.

Why it matters:

• Maximum flexibility: choose the biomolecule you conjugate based on your specific target and assay design.
• Coupling density can be optimized by adjusting protein:bead ratio during conjugation.
• Multiple coupling chemistries available depending on the specific surface group (see Surface Chemistry chip).
• Conjugation kits are available to simplify the workflow and reduce protocol development time.

How to interpret here: This product is Activated (Ready-to-conjugate). You will need to perform a coupling reaction to attach your specific antibody, protein, or oligonucleotide before use. Follow the coupling protocol in the Documents section; conjugation kits providing all required buffers are available separately.

Tip: Always test conjugation efficiency (e.g., by BCA assay on the supernatant after magnetic separation) before scaling up to full assay development.

What it means: Aqueous dispersion means this product is supplied as a colloidal suspension in an aqueous buffer (typically PBS, DI water, or a proprietary storage buffer). The particles are dispersed and ready for use in water-based biological applications without any solvent exchange step.

Why it matters:

• Compatible directly with cell culture media, PBS, HEPES, and other standard biological buffers.
• No solvent exchange or phase transfer required before use in aqueous assay protocols.
• Aqueous colloidal stability maintained by surface coating (polymer, PEG, or functional group layer).
• Bath sonication before use ensures complete resuspension after storage sedimentation.

How to interpret here: This product is in Aqueous dispersion. It can be used directly in your assay buffer after resuspension. Confirm compatibility with your specific buffer conditions (ionic strength, pH, protein concentration) by checking the product specification sheet or running a small-scale stability test.

Tip: High ionic strength buffers (>500 mM) or pH extremes outside the specification range may compromise colloidal stability. Always validate in your specific matrix.

What it means: Applications list the primary experimental workflows this product has been used for: Immunoassay, Cell Separation, Protein Separation.

Why it matters:

• Immunoassay: this product can directly support this workflow based on its surface chemistry and particle properties.
• Cell Separation: this product can directly support this workflow based on its surface chemistry and particle properties.
• Protein Separation: this product can directly support this workflow based on its surface chemistry and particle properties.

How to interpret here: This product is suited for the listed applications. The most relevant for this product are Immunoassay, Cell Separation. Review the application-specific protocol in the Documents section before beginning workflow development.

Tip: Application suitability depends on specific experimental conditions (buffer, sample matrix, target concentration). Always validate at pilot scale before full assay development.