Biotin-Streptavidin Systems and the Benefit of MegAvidin in Lateral Flow Assay (LFA) Applications

Background on streptavidin and biotin

Streptavidin is a 52,000 dalton molecular weight protein derived from the bacterium Streptomyces avidinii. Each streptavidin is capable of binding four biotin molecules with the greatest known affinity between a binding protein and its ligand (Kₐ = 10¹⁵ M⁻¹).

Biotin is a 244 dalton molecular weight vitamin (Vitamin H). Its small size and the wide availability of effective biotinylation reagents enables labeling of antibodies, oligonucleotides and other biomolecules without significant inactivation of the labeled biomolecule.

Applications of streptavidin

This combination of extreme affinity and ease with which active, biotinylated reagents may be prepared makes biotin-streptavidin formats useful in constructing high sensitivity assays.

Biotin-streptavidin formats find utility in Enzyme-Linked ImmunoSorbent Assays (ELISA), immunohistochemistry (IHC), Lateral Flow Assays (LFA), Microarrays, Flow Cytometry, and DNA/RNA amplicon detection assays. These assay formats use wide ranging detection labels including enzymes, isotopes, fluorophores, nanoparticles, and quantum dots. The general applicability of the method is one of its great strengths, and an assay configuration involving biotin-streptavidin is typically the most sensitive assay achievable.

Description of MegAvidin

MegAvidin is a polymerized preparation of streptavidin. As such, it retains the high affinity and specificity of streptavidin, but its increased size enhances its adhesion to surfaces. In our experience, most surface based assays exhibit greater sensitivity and binding capacity using MegAvidin compared to streptavidin.

MegAvidin vs Streptavidin in Lateral Flow Assays (LFA)

An example of MegAvidin’s increased binding ability and sensitivity is visually demonstrated by its use in Lateral Flow Assays. When MegAvidin and streptavidin are striped (deposited onto nitrocellulose membrane) as a test line, MegAvidin consistently produces more intense lines and increased sensitivity.

The increased binding capacity of MegAvidin also allows the use of increased concentrations of biotinylated ligands (e.g., > 100 nM concentration of biotinylated antibody) without saturation of biotin binding sites, often resulting in additional assay sensitivity.

To learn more about available MegAvidin products or to talk with an Applications Scientist about how BioAssay Partner's MegAvidin may assist in your research, visit us at bioassaypartners.com. We look forward to partnering with you!