Antigen—antibody competitive reactions

Since the development of radioimmunoassay (RIA), many assays that rely on the specificity of the antigen-antibody binding reaction have been developed because of their inherent sensitivity and specificity. A typical competitive binding... 

Figure 10. Proposed Adaptation of a Fluorescence Energy Transfer Immunoassay to the Microparticle Sensor Design. A mixture of two different microparticles, each containing different reagents, are entrapped physically in the polyacrylamide layer. The reagents released from the microparticles set up a competition reaction between the free and labeled antigens for the available binding sites of labeled-antibody. The immunocomplexes formed have different emission spectra, allowing quantitation of free antigen concentration.

Bound fraction Antigen/competitor present as a complex, attached to the corresponding antibody the fi-action of the reaction mixture which contains the antigen-antibody complex Carrier protein Large non-immunogenic protein that, when coupled to a hapten, induces production of anti-hapten antibodies in an animal Competitive assay Immunoassay based on the principle of competition between the analyte in the sample ( unknown ) and competitor Competitor Antigen derivative that is modified (i.e., labelled, coupled to a large protein) and serves for indirect detection of the analsde in competitive immunoassays... 

The future use of coated piezoelectric devices as immunochemical sensors, even directly in the liquid phase, is very promising and could be considered a very competitive alternative to other types of immunoassay. Only this technique and that of surface plasmon resonance provide labelless methods for the direct study of antigen-antibody reactions, and their analytical possibilities. The devices can be easily automated or combined with flow injection systems, extending their capability of continuous and repeated assays. This raises an exciting possibility of using crystal arrays to assay for different analytes in complex samples with an on-line display of the results. 

Immunoassay techniques generally involve a competitive reaction between an analyte antigen and a standard antigen that has been tagged, for limited binding sites on the antibody to that antigen. The tag may be a radioactive tracer, an enzyme, or a fiuorophore. We describe below the immunoassay technique as well... 

Immunoassay techniques are based on the antigen-antibody interaction. These techniques involve a competitive reaction between antigen molecules of the target molecules and labeled antigen molecules for a limited number of antibodies. Enzyme-linked immunosorbent assays (ELISA) in which antibodies are immobilized on a solid phase are the most popular for pesticide detection. As pesticides are small molecules, in order to synthesize antibodies, pesticide derivatives (haptens) must be synthesized and coupled to carrier proteins. ... 

A fiber-optic flow-injection analysis in which a fluorescent reporter molecule is utilized to monitor a competition reaction between a labelled and an unlabelled antigen molecule for an immobilized antibody has been reported [100]. It is based on the evanescent wave technique. 

Competitive reaction between the solid-phase antigen and the hapten in the sample solution with first antibody... 

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