Immobilization direct

Wei, Y., Xu, J., Feng, Q., Lin, M., Dong, H., Zhang, W.-J. and Wang, C. (2001) A novel method for enzyme immobilization direct encapsulation of add phosphatase in nanoporous silica host materials. Journal of Nanoscience and Nanotechnology, 1, 83-93. 

As schematically depicted in Figure 5, two different routes are available for immobilizing biotin-labeled enzymes on the support through avidin-biotin complexation. The first procedure employs the biotin-modified surface on which biotin-labeled enzymes are immobilized through avidin as binder protein. For this procedure, the covalent linkage of biotin onto the surface of a carbon electrode and the preparation of biotin-labeled lipid bilayer on electrode have been studied. An alternative way involves the direct modification of an electrode surface with avidin. If avidin could be immobilized directly without loss of the binding activity to biotin, biotin-labeled enzymes could be loaded more easily on the electrode surface. 

Affinity chromatography, first described by Cuatrecasas et al.,U9 utilizes the ability of a protein or another biopolymer to recognize a natural or synthetic ligand. The affinity chromatography sorbent consists of a porous matrix itself on which a ligand is chemically immobilized directly or by means of a spacer arm. 

Sensitive, selective detection of biochemically active compounds can be achieved by employing antigen-antibody, enzyme-substrate, and other receptor-protein pairs, several of which have been utilized in the development of piezoelectric immunoassay devices. The potential analytical uses of these materials has been reviewed, particularly with respect to the development of biochemical sensors [221-224], The receptor protein (e.g., enzyme, antibody) can be immobilized directly on the sensor surface, or it can be suspended in a suitable film or membrane. An example of the sensitivity and response range that can be... 

In one of the first reports of a carbohydrate microarray, under-ivatized polysaccharides and glycoproteins were immobilized directly on nitrocellulose-coated glass slides (10). In a further demonstration of the feasibility of noncovalent immobilization of underivatized glycans, Willats et al. reported microarrays of glycoproteins, proteoglycans, and polysaccharides on oxidized black polystyrene slides (11). Modified neutral and aiuoiuc dex-tran polysaccharides have also been synthesized and printed on semicarbazide-coated glass slides (12). 

Wacker R, Schroder H, Niemeyer CM (2004) Performance of antibody microarrays fabricated by either DNA-directed immobilization, direct spotting, or streptavidin-biotin attachment a comparative study. Anal Biochem 330 281-287... 

DTSP-modified crystals can be used to immobilize directly proteins through surface aminogroups by simple incubation for 2h at room temperature. The concentration of proteins can be from 10 to 1,000 pg/mL. 

Direct or Sandwich ELISA The direct format represents the most simplified ELISA system. In this assay, serum or plasma samples are incubated with the antigen (usually the drug), which has been previously immobilized directly onto well surfaces of microtiter plates. The bound antibody is detected using an enzyme-labeled anti-immunoglobulin reagent of appropriate specificity. 

Promising new approaches include the specific and covalent surface immobilization of fusion-tagged proteins. One recent example utilizes a fusion tag composed of a mutant of the human DNA repair protein 0 -alkylguanine-DNA alkyltransferase (hAGT) [42]. A derivative of 0 -bensylguanine was immobihzed to carboxymethylated dextran surfaces and selective coupling of the fusion protein was obtained. Specific immobilization directly from crude cell extracts that expressed the hAGT fusion protein was also demonstrated. 

The complex [Mn(4-OHsalhd)CH3COO] [Figure 8.4(a)] was immobilized directly onto untreated and air- or acid-oxidized ACs with adsorption efficiencies of 30, 77, and 62%, respectively, indicating that oxidation of the AC... 

Several metalloporphyrins and phthalocyanines and numerous coordination and organometallic complexes of Rh, Ir, and Pd have also been immobilized directly onto micro- and mesoporous carbon materials, as well as onto CNTs. 

Besides semiconducting SWCNTs, properly doped diamonds can also be nsed as the channel material for fabricating FETs for biosensing as demonstrated by Song et al. [75]. DNA probes are immobilized directly on the aminated snr-face of a p-type polycrystalline diamond film which serves as the conduction channel between the source and drain electrodes. Since a diamond surface is chemically stable and presents a wide potential window, it permits direct contact of biomolecules with the channel surface, eliminating the needs of a polymer coating (in CNT FETs) or dielectric encapsulation (in Si-FETs). As a result, diamond FET is potentially a much more sensitive and faster biosensor, which can operate in solution. Hybridization with complementary and 3-mer mismatched DNA targets in 10 pM can be discriminated in cyclically repeated hybridization and denatnre experiments. 

Figure 7.3-2. Matrix-based DNA delivery can be divided into encapsulation and release approaches, where the nucleic acid is encapsulated for later release, and matrix-tethered delivery, where nucleic acid polyplexes or lipoplexes are immobilized directly to a matrix that also supports cell adhesion. These approaches are typically used for applications in tissue engineering where the delivery of nucleic acids is used to augment tissue formation.

So we considered that if the whole microbial cells could be immobilized directly, these disadvantages might be overcome, and we studied the immobilization of whole microbial cells. Reports on immobilization of whole microbial cells had been very scarce at that time, so we tried various methods for Immobilization of... 

Typical indicator-mediated fiber-optic-sensor configurations are shown schematically in Figure 6.2. In (a) the indicator is immobilized directly on a membrane positioned at the end of a fiber. An indicator in the form of a powder can be either glued directly onto a membrane, as shown in (b), or physically retained in position at the end of the fiber by a special permeable membrane (c), a tubular capillary/ membrane (d), or a hollow capillary tube (e). 

Compared to the "grafting to" approach, the "grafting from" method presents an evident superiority, offering a more homogenous MIP coverage of the sensor s surface with a larger number of cavities and a 100-fold faster diffusion of analyte [45], However, the initiator s immobilization directly onto the surface is usually complex and chemically not tenable [53],... 

Scone of Sensor Fabrication for Immobilized Direct Dves at Porous gsUtfl9Sig Films,... 

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