Streptavidin polystyrene

FIGURE 7.43. Addition of streptavidin to the biotinylated polystyrene amphiphile (left) results in a biohybrid monolayer, which can be further funtionalized by the addition of biotinylated proteins/enzymes (schematic representation in the middle). TEM image of a ferritin-streptavidin-polystyrene monolayer. Each black spot represents a single ferritin. 

The biotinylated aptamer was easily immobilized on a streptavidin polystyrene-divnyl benzene support. Enantiomers of small biomolecules were also resolved efficiently (Michaud et al., 2004). To develop this strategy on a large scale, several problems have to be solved, notably the cost and the problem of the aptamer stability if samples contaminated with nucleases are used. Solutions discussed above (modified oligonucleotides) can be considered. 

Sulfonated 8 and biotinylated polymer 38-coated streptavidin-derivatized polystyrene microspheres were useful as a platform for the detection of DNA... 

Wilson JN, Wang Y, Lavigne JJ, Bunz UHF. A biosensing model system selective interaction of biotinylated PPEs with streptavidin-coated polystyrene microspheres. Chem Commun 2003 1626-1627. 

In protein microarrays, capture molecules need to be immobilized in a functional state on a solid support. In principle, the format of the assay system does not limit the choice of appropriate surface chemistry. The same immobilization procedure can be applied for both planar and bead-based systems. Proteins can be immobilized on various surfaces (Fig. 1) (12). Two-dimensional polystyrene, polylysine, aminosilane, or aldehyde, epoxy- or thiol group-coated surfaces can be used to immobilize proteins via noncovalent or covalent attachment (13,14). Three-dimensional supports like nitrocellulose or hydrogel-coated surfaces enable the immobilization of the proteins in a network structure. Larger quantities of proteins can be immobilized and kept in a functional state. Affinity binding reagents such as protein A, G, and L can be used to immobilize antibodies (15), streptavidin is used for biotinylated proteins (16), chelate for His-tagged proteins (17, 18), anti-GST antibodies for GST fusion proteins (19), and oligonucleotides for cDNA or mRNA-protein hybrids (20). 

The third approach made use of the streptavidin-biotin couple to connect enzymes to hydrophobic polymer tails (Figure 6.11c) [36]. In the first step of the self-assembly, two biotin-functionalized polystyrene chains (90 repeat units, PDI =... 

Figure 8 Chemiluminescent (A and B) and bioluminescent (C) detections for immobilized hybridizations of PCR product. Dg, digoxigenin Bt, biotin Ad, avidin. Procedure A [30] Biotin moiety is incorporated into PCR products during the amplification reaction, using one 5 -biotinylated primer. The product is hybridized with a Dg-labeled probe and is immobilized on streptavidin-coated magnetic beads. This capture reaction is carried out for 30 min at 37°C. A permanent magnet is used to sediment the beads during washing to remove unbound DNA. By incubation with the washed beads for 45 min at 37°C, anti-Dg antibody conjugated to HRP enzyme is bound to the Dg-labeled probe, and luminol reaction is performed for CL detection. Procedure B [31] Wells of a polystyrene microtiter plate are activated with l-ethyl-3-(3-dimethylaminopropyl)-carbodiimide, and then coated with a labeled cDNA probe complementary to an internal region of the target DNA.

Fig.26 Pseudo-color time-resolved image of polystyrene nanobeads containing Pt porphyrin and conjugated to streptavidin immobilized to a biotinylated microarray surface (black teflon coated 96-well glass slide, spot diameter 1 mm, Erie Scientific) in different concentrations (25, 15, 10, 5, Ong streptavidin per well) [167]...

In one report, the optical tweezers were used to hold a bend in order to stretch a DNA molecule. First, a DNA molecule (XDNA) was biotin-congugated so that it could be attached to a streptavidin-coated polystyrene bead. The bead was held by optical tweezers inside a PDMS chip. The other end of the DNA was labeled with digoxigenin to be immobilized on the channel coated with anti-digoxigenin antibody. The DNA was stretched by moving the chip, with the bead being held by the optical tweezers [868]. 

Figure 8.15 Schematic illustration of amplified DNA detection employing probe DNA modified magnetic beads, (a) Treatment of probe with target DNA modified with streptavidin-conjugated polystyrene beads loaded with biotinlyated AuNPs followed by (b) Au precipitation onto AuNP seeds, (c) dissolution of the Au, and (d) detection via electrochemical stripping.71 (Adapted with permission from A.-N. Kawde and J. Wang, Electroanalysis 2004, 16, 101-107. Copyright Wiley-VCH Verlag GmbH Co. KGaA.)...

An example of the immobilization on polystyrene beads is the bead-bed micro-ELISA system of Kitamori et al. [403]. The beads were coated with a capture antibody and loaded into the reaction channel of the ELISA microchip (Scheme 4.92a). Next, solutions containing antigen (Scheme 4.92b), a biotinylated secondary antibody (Scheme 4.92c) and a streptavidin-peroxidase conjugate were introduced into the channel (Scheme 4.92d). Finally, the substrate for peroxidase was continuously... 

X. Gao, H. J. Mathieu, and M. Schawaller, Surface modification of polystyrene biochip for biotin labelled protein/StreptAvidin and NeutrAvidin coupling used in fluorescence assay,... 

Another use for drug conjugation is for signal labeling. For example, the drug will be conjugated to an enzyme in EIA to biotin, avidin, or streptavidin in biotin amplification to a protein for adsorption onto a solid-phase support or to polystyrene beads by direct covalent linkage. 

Fig. 5. Anti-gastrin antibody binding capacity of biotinylated gastrin captured by polystyrene-adsorbed streptavidin biotinyl-cysteamine/Na-maleoyl-J3-alanyl-[Nle15]-gastrin-[2-17] adduct (0—0) and biotinyl-NH-fCH -CO-Gly-Pro-[Nle15]-gastrin-[2-l 7] (A-A).

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