Avidin-Biotin Affinity Reactions

Numerous studies on bead bio chips were therefore based on magnetic [16,17], glass or silica [18-20], and polystyrene beads [21]. The DNA immobilization chemistry of those beads could be very different, from the classical avidin/biotin affinity reaction [17,22] (Fig. 2B) to the disulfide bridging onto thiol modified silica [19] (Fig. 5A), the thiocyanate reaction onto amino-terminated latex beads [21] (Fig. 5B), and finally the hybridization-based immobilization of poly(A)-tagged probes onto poly(T)-bearing magnetic beads [16] (Fig. 5C). 

Fig. 12 Schematic illustration of immobilization strategy using affinity reactions via avidin-biotin coupling. Biotinylated mixed monolayers improve the availability of the surface-bound avidin or streptavidin to biotin coupled probe biomolecules...

Q Yang, X-Y Liu, M Hara, P Lundahl, J Miyake. Quantitative affinity chromatographic studies of mitochondrial cytochrome c binding to bacterial photosynthetic reaction center, reconstituted in liposome membranes and immobilized by detergent dialysis and avidin-biotin binding. Anal Chem 280 94-102, 2000. 

Several other methods are proposed, such as use of coulomb force between anionic DNA and cationic particle (7), use of biospecific affinity between biotin-labeled DNA and avidin-carrying particle (8), etc. Other methods for immobilization of DNA on the particle include reactions using cyanogen bromide, glutaraldehyde, and cyanuric chloride (9). 

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