Micro-Immunomagnetic Bead-Streptavidin (GMLS-Tag004-microIMB-1)

1 µm beads: Possess a higher specific surface area and a higher streptavidin loading capacity. They exhibit exceptionally high capture efficiency for short-fragment nucleic acids (e.g., oligos, trace cell-free DNA [cfDNA]) and are highly suitable for high-sensitivity molecular diagnostics and high-throughput sequencing library construction.

2.8 µm beads: Due to their larger particle size, they demonstrate superior kinematic compliance and extremely rapid magnetic response in high-viscosity liquids (e.g., unpurified whole blood lysates, complex suspension systems). Furthermore, they exert moderate physical shear stress, making them more appropriate for capturing long-fragment DNA (e.g., genomic DNA) or the pull-down of macromolecular complexes, effectively preventing the breakage of long chains.

This series of magnetic beads utilizes multi-point covalent coupling technology to immobilize streptavidin. They are extremely stable under standard high-temperature decolorization or elution conditions (e.g., 80°C for 2-5 minutes), and the solid-phase monomers (with a reducing electrophoretic molecular weight of approximately 15 kDa) do not shed easily. However, prolonged exposure to strong acidic (pH < 2) or strong alkaline (pH > 11) environments may cause irreversible dissociation of the tetrameric structure of the recombinant streptavidin, leading to a decrease in binding capacity.

We recommend optimizing from the following three dimensions:
Wash buffer formulation: Introduce 0.1% - 0.5% non-ionic surfactants (e.g., Tween-20 or Triton X-100) into the wash buffer and supplement with NaCl to a final concentration of 0.15-0.2 M to attenuate electrostatic non-specific interactions.

Thorough blocking: Prior to use, the magnetic beads can be blocked with small molecules using 1 M Ethanolamine or 1 M Tris (pH 7.4-8.0). If it does not interfere with downstream mass spectrometry (MS) analysis, 1% purified BSA or casein can also be added. Operational details: During the final wash step of magnetic separation, transfer the beads to a brand-new microcentrifuge tube (EP tube) to prevent non-specific adsorbates residing on the original tube wall from being carried over into the downstream system.

The traditional biotin-streptavidin interaction is extremely difficult to dissociate under mild conditions. If the downstream application involves MS analysis or SDS-PAGE, it is recommended to use an elution buffer containing 1× SDS Loading Buffer (with or without reducing agents) and perform heat denaturation at 80°C-95°C for 5 minutes. This completely denatures the proteins, forcefully releasing the target proteins and nucleic acids. During this process, the covalently bound monomers on the bead surface do not shed easily and will not interfere with MS identification.

Absolutely not. Freezing induces localized ice crystal growth, generating immense physical compressive stress that destroys the polymer backbone matrix of the magnetic beads. This leads to bead fragmentation and irreversible spatial structural alterations or shedding of the surface-coupled recombinant streptavidin. Frozen magnetic beads will exhibit severe and irreversible aggregation, accelerated sedimentation, and decreased binding capacity, and must be discarded.