Surface chemistries and applications

Magnetic beads come in a range of surface chemistries and sizes to meet different application requirements. Table 1 below gives an overview of the various magnetic bead types, with their key properties and applications. Table 2 lists application-specific kits that are available from Cytiva.


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

    Table 2. Application-specific kits for reliability and convenience

    Kit Application Learn more
    Sera-Xtracta Virus/Pathogen Kit Sensitive detection of total nucleic acid (RNA and DNA) from swabs, blood and transport media App note: Purification of DNA/RNA viruses and bacteria from oropharyngeal swabs and blood.
    Sera-Xtracta Cell-Free DNA Kit Capture of highly fragmented cfDNA while minimizing co-purification of higher molecular weight DNA Detection of cancer-associated mutations in liquid biopsies for the identification of therapeutic targets
    Sera-Xtracta Genomic DNA Kit Extraction and purification of genomic DNA from whole blood Quick start protocol