Surface chemistries and applications

Magnetic beads come in a range of surface chemistries and sizes to meet different application requirements. The table below gives an overview of the various magnetic bead types, with their key properties and applications.


Table 1. Comparison of magnetic bead surface chemistries and applications

Type Properties Applications Variations
Carboxylate-modified magnetic beads
  • Can associate with nucleic acids for direct capture.
  • Surface suitable for conjugation through covalent bonding.
  • Can capture molecules containing amino groups.
Conjugation or direct binding applications:
  • Covalent attachment
  • Affinity purification and pull-down
  • Nucleic acid isolation and purification
  • NGS size selection
  • High-speed version available
    Amine-blocked magnetic beads
    • Surface suitable for conjugation through covalent bonding.
    • Non-surfactant, non-protein-blocked surface.
    • Low non-specific binding.
    Conjugation applications, similar to carboxylate-modified beads. High-speed version available
    Oligo(dT)-coated magnetic beads
    • Hybridizes with mRNA poly-A tails.
    • High colloidal stability.
    mRNA binding applications:
    • mRNA extraction and purification
    • RT-PCR
    • cDNA library construction
    • Subtractive hybridization
    • NGS (RNA sequencing)
    Streptavidin-coated magnetic beads
    • Binds biotinylated ligands such as proteins, nucleic acids, and peptides.
    • Covalently bound streptavidin coating.
    • Fast reaction kinetics.
    • Low non-specific binding.
    • High throughput and precision.
    Immunoassay and molecular biology applications:
    • Sample preparation and assay development for genomics and proteomics.
    High-speed version available
    Biotin binding ranges:
    • 2500 to 3500 pmol/mg
    • 3500 to 4500 pmol/mg
    • 4500 to 5500 pmol/mg
    Streptavidin-blocked magnetic beads
    • Binds biotinylated ligands such as proteins, nucleic acids, and peptides.
    • Non-surfactant, non-protein-blocked surface.
    • Lower non-specific binding than streptavidin-coated beads via additional blocking of non-specific binding sites.
    High-specificity biotin binding applications
    • Molecular and immunodiagnostics
    • NGS library preparation
    High-speed version available
    NeutrAvidin™-coated magnetic beads
    • Binds biotinylated ligands such as proteins, nucleic acids, and peptides.
    • Fast reaction kinetics.
    • Low non-specific binding.
    • High throughput and precision.
    Alternative to Streptavidin in immunoassay and molecular biology applications:
    • Sample preparation and assay development for genomics and proteomics.
    High-speed version available
    Biotin binding range:
    • 3500 to 4500 pmol/mg
    Protein A/G magnetic beads
    • Binds IgA and IgG proteins
    • Coating based on IgA/IgG fusion protein.
    • Broad binding capabilities.
    Antibody isolation applications:
    • Affinity purification and pull-down
    • Immunoprecipitation
    Silica-coated magnetic beads
    • Reversibly binds nucleic acids based on salt concentration.
    • Monodisperse particles with narrow size ranges of 400 µm or 700 µm.
    Applications with low sample amounts
    • Nucleic acid extraction for molecular diagnostics applications such as qPCR.
    Mag Sepharose
    • Broad range of ligand options.
    • Porous, providing greater surface area than other magnetic beads.
    Convenient alternative to sepharose columns, with protein purification applications including:
    • Affinity purification or capture
    • Immunoprecipitation