Biotinylated protein layer

Guided mode calculations were also carried out to compare the sensor response of several waveguide systems. In these simulations a model molecular monolayer is represented by a 2-nm thick layer with a refractive index of n 1.5. The optical properties of this model layer are typical of a dense layer of organic molecules on a substrate1 41, and are a reasonable approximation for a streptavidin protein layer bound to a biotinylated surface, the experimental model system we use to characterize our sensors. The ambient upper cladding was assumed to be water with a refractive index of n 1.32. For all examples, the lower cladding was assumed to be Si02 with an index of n 1.44. In the simulations, the effective index of... 

Ringsdorf and coworkers used monolayer techniques for the creation of lipid functionalized streptavidin layers.252,253 In their pioneering work, a monolayer of biotinylated phospholipids initially created a two-dimensional docking matrix for the immobilization of streptavidin. In an effort to further expand this system while maintaining control over its structure, bis-biotinylated bifunctional linkers were employed. Addition of these linkers to concanavalin A created a new protein-based bidentate linker. Upon addition to the monolayer of the lipid-functionalized streptavidin a second biotilynated protein layer was created. Upon the further addition of streptavidin, they achieved in a step-by-step construction process well-defined alternating protein triple layers of streptavidin and concanavalin A (Figure 7.37b). A similar approach has more recently been used to crosslink... 

Fig. 4 Macromolecular bioconjugates created using bifunctional streptavidins. Here, a biotinylated single-stranded DNA is bound to immobilized streptavidin. A complementary strand covalently attached to streptavidin is hybridized to the immobilized DNA, and a biotinylated protein is bound to the floating streptavidin layer...

Figure 6.5 Biotin head groups of a surface monolayer bind strongly to the protein streptavidin containing four biotin binding centres. A crystalline protein layer can now be observed by electron microscopy. The other binding centres can now be used to form a third monolayer with biotinylated proteins, e.g. the FAB fragment of F immunoglobulins. ...

These findings led us to a strategy for optimized protein binding even at well-ordered monolayers by using binary mixtures of biotin -and OH -terminated self-assembly systems. Figure 3 shows the surface-plasmon optical results of the thickness determinations for co-adsorbed SAM s and of their streptavidin binding. The striking result is the maximum protein layer thickness at ca 5-10 mole% biotinylated thiol indi-... 

Avidin-biotin systems. Stable and highly active protein-LB/LS film composites can be accessed using avidin-biotin conjugation techniques. Thus, sensor elements displaying biotinylated GOx and phycoerythrin, and streptavidin and av-idin conjugates of phycoerj tiirin, have been bound to avidin-lipid and biotinylated lipid-streptavidin LB films, or biotinylated lipid layers have been produced [71-73]. 

Fig. 14 A schematic illustration of an orientated immobilization strategy via crystallized S-layer proteins a side view of the crystalline ordered S-layer proteins fused with the recognition center streptavidin for biotinylated biomolecules probes b front view of the orientated and crystalline ordered S-layer proteins...

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