Competitive homogeneous assay format

Enzyme-multiplied immunoassay technique Perhaps the best known homogeneous assay format is the enzyme-multiplied immunoassay technique (EMIT), in which the analyte is covalently attached to an enzyme, and the formation of an analyte-antibody complex blocks the active site and inhibits enzyme activity. When this blocked enzyme is mixed with the experimental sample, there is competition between the enzyme-linked analyte and the sample analyte for occupation of the antibody s antigen-binding site. The more of the analyte present in the sample, the more of the enzyme is released from inhibition, and the level of enzyme activity can thus be used to determine the quantity of the analyte. 

Immunoassays can be classified according to different criteria. The particular type selected has a strong influence on the assay performance with regard to precision and sensitivity. The main criteria include [3, 22, 23] (1) labeled or unlabeled assay formats, with different type of labels (2) competitive or non-competitive immunoassays, and (3) homogeneous or heterogeneous immunoassays. These classifications can also be extended to MIP-ILAs (Fig. 2) ... 

Homogeneous enzyme immunoassays use a competitive assay format that relies on a reduction in the rate of enzyme catalysis of Ag as it binds to the Ab. The general equilibrium scheme for homogeneous immunoassays, which also holds true for the nonenzymatic ones discussed later, is shown in Fig. 4. The... 

Lanthanide-labelled immunoreagents have been applied in different types of single and multilabel immunoassays e.g. non-competitive, competitive assays (7,10,16,18) and in non-separation or homogeneous formats (20,21,22,23). 

As in FIAs, different formats such as competitive assays, two-site assays, double antibody assays, are possible in CLIAs also. Both heterogeneous and homogeneous CLIAs have been developed. However,... 

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