Biotin- avidine interaction

The non-radioactive labeling utilizes fluorescence, chemiluminescence, or biotin/avidin interactions. Capillary electrophoresis with laser-induced fluorescence was first employed in PAL by Miller et al. [51]. Gilbert and Rando recently reported several biotin-containing heterobifunctional reagents and used them successfully [18] (Fig. 5). 

Affinity immobilization based on biotin- avidin interactions... 

In terms of biosensing applications using such layers, again cholera toxin detection on a porous silicon substrate [85] has been reported. Also biotin-avidin interaction by QCM [86], glutamate detection [87], as well as protein membrane interactions [88, 89] have been studied. 

Biotin-avidin interaction. The cellular delivery capacity of several CPPs has been proven using complexes of biotinylated peptides with labeled avidin or strep-tavidin (23,27,37). Avidin could also serve as a scaffold for the assembly of molecules to be delivered into cells using biotinylated CPPs to facilitate the uptake process. 

Fig. 1. Different strategies of coupling cargoes to cell-penetrating peptides. (I) Non-covalent coupling by electrostatic interactions (A) (44,46), specific pairing of nucleotides (B) (39,48), biotin-avidin interaction (C) (37,66) or mixed-type interactions (D) (26). (II) Covalent coupling by connecting CPP and cargo molecule into a continuous chain (E) (36), forming a disulfide bond (F) (49,56) or chemical crosslinking (G) (37,57).

One distinct advantage of this system, i.e., the use of the MIANS label in conjunction with the anti-MIANS affinity column, over a similar approach, e.g., using the biotin-avidin interaction, is that the MIANS label can be tracked at a wavelength, approximately 320 nm, which is unique from the peptide or protein absorbance spectrum (Gupte and Leine, 1979 Andley et al., 1986). Another potential advantage is that the anti-MIANS colunm is reusable. The column has been routinely regenerated for multiple uses. 

To efficiently monitor the interaction between a small molecule and a protein expressed on the phage surface, the small molecule is to be immobilized on the solid surface. Generally, biotin-avidin interaction has been used for this purpose. Biotin is covalently linked to the specific functional group of a small molecule that does not affect its biological effect on cells. Small molecules can be linked... 

An oligosaccharide mixture derivatized with 2,6-diaminopyridine-modified biotin can be efficiently separated by reverse-phase HPLC [57] and the separated oligosaccharide derivatives can be used for construction of neoglycoproteins via the biotin-avidin interaction. 

The main challenge in the field of electrochemical sensors and devices is the use of the conductivity of the polymer matrix to address electronically the active centre. For example, a major issue lies in the devices based on the biotine--avidine interaction. Of course it is possible to operate with a monolayer, but this diminishes the efficiency of the sensor. However, if the material between the sensing part and the electrode is a conducting polymer, the electron transfer occurs usually more efficiently and allows to operate with multilayered systems, as it has been demonstrated by Cosnier et al. [362-364] (Scheme 18.10). 

Similar assays for measuring protease activity were also reported by Whitten and coworkers [49], These assays utilize polystyrene microspheres that are coated with streptavidin (a biotin-binding protein) and a biotinylated anionic fluorescent conjugated polyelectrolyte or a cationic polyelectrolyte, A biotinylated quencher-labeled peptide serves as a substrate for the enzyme and when mixed with the microspheres, a strong complex similar to the one in the DNA assays described in Section 13,3,1, through the biotin-avidin interaction is created [49], A schematic drawing of the assay is shown in Figure 13,7,... 

In a subsequent study Leclerc et al. [42] prepared water-soluble biochromic poly-(2-(4-methyl-3 -thienyloxy)ethanesulfonic acid) based on biotin-avidin interactions as shown in Figure 4.26. They suggest that the self-acid-doped poly-(2-(4-methyl-3 -thienyloxy)ethanesulfonic acid) can react with various basic molecules, such as n-butylamine and... 

Hydrophobic interaction (fluoro-tagged compounds and fluorinated PSi) Biotin-avidin interaction Fluoro-tagged compounds and fluorinated PSi ... 

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