Biotin-streptavidin complex

Liposome conjugates may be used in various immunoassay procedures. The lipid vesicle can provide a multivalent surface to accommodate numerous antigen-antibody interactions and thus increase the sensitivity of an assay. At the same time, it can function as a vessel to carry encapsulated detection components needed for the assay system. This type of enzyme-linked immunosorbent assay (ELISA) is called a liposome immunosorbent assay or LISA. One method of using liposomes in an immunoassay is to modify the surface so that it can interact to form biotin-avidin or biotin-streptavidin complexes. The avidin-biotin interaction can be used to increase detectability or sensitivity in immunoassay tests (Chapter 23) (Savage et al., 1992). 

O Shannessy, D.J., Voorstad, P.J., and Quarles, R.H. (1987) Quantitation of glycoproteins on electroblots using the biotin—Streptavidin complex. Anal. Biochem. 163, 204-209. 

One method of using liposomes in an immunoassay is to modify the surface so that it can interact to form biotin—avidin or biotin—streptavidin complexes. The avidin— biotin interaction can be used to increase detectability or sensitivity in immunoassay tests (Chapter 13) (Savage et al., 1992). 

Jurinke C, van den Boom D, Collazo V, Luchow A, Jacob A, Koster H. Recovery of nucleic acids from immobilized biotin-streptavidin complexes using ammonium hydroxide and applications in MALDI-TOF mass spectrometry. Anal Chem 1997 69 904-910. 

Figure 3 Exclusively enthalpy-driven complexes (a) biotin-streptavidin complex as one of the tightest binding biomolecular systans, achieving an extraordinarily high affinity of 10 M through noncovalent interactions (created by the PyMol software based on PDB entry 2izf) (b) CB[7] complex with l,l -bis(trimethylammoniomethyl)ferrocene as the tightest man-made supramolecular complex that also achieves an extraordinarily high affinity of 10 M through noncovalent interactions.

Figure 11 Binding of streptavidin and anti-biotin mAb to a biotin-functionalized gold nanoparticle monolayer studied by surface plasmon absorbance of gold nanoparticles at 550 nm. (A) Baseline extinction in PBS-Tween as a function of time. (B) Incubation of the biotin-functionalized surface with streptavidin (10 ig/ml) or antibiotin mAb (50 pg/ml) results in an increase in the absorbance due to protein-ligand binding. No increase in extinction was observed on incubation of biotin-functionalized surface with BSA(10 pg/ml) (a), human IgG (50 pg/ml) (b) or streptavidin (30 g/ml) pre-incubated with 1.0 mM biotin (c). (C) Incubation of the protein-ligand complex on the surface with I mM biotin in solution causes decrease in signal due to dissociation of biotin-mAb complex. No dissociation was observed for biotin-streptavidin complex due to its slow off-rate constant.

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