Assay heterogeneous

The DELFIA assay, the first effective lanthanide-based immunoassay, was developed and commercialized by the early 1980s.108-112 DELFIA (Dissociation Enhanced Lanthanide Fluoro-ImmunoAssay) is a heterogeneous assay which uses a lanthanide complex based on aminocarboxylate ligands such as EDTA, EGTA, or DTPA, linked to the antibody by reaction of appended isothiocyanate groups (e.g., complex (45)) with nucleophilic residues, particularly amines, on the protein surface (Figure 11). 

Among the heterogeneous assays, EFISA is the most common and frequently used for environmental monitoring. Examples of its wide applicability can be found in recent reviews [71,79]. The most usual configurations for the analy-... 

PERFORMANCE AS A REAGENT ON STRATUS SYSTEMS 4.2.1 Heterogeneous Assay Format... 

Heterogeneous assays are those that require separation of the bound fraction from the free. 

For each of these types of immunoassay, in order to observe the ratio of bound to free in the final reaction mixture, a method has to be employed which will separate these fractions and various ingenious ways have been devised to do this. Techniques which require the separation of free from bound fractions are referred to as heterogeneous assay systems. 

Interference by other thiols (e.g. as enzyme buffer components) Homogeneous assay, commerically available components Heterogeneous assay, very low assay volume possible Heterogeneous assay... 

Heterogeneous assay, very low assay volume possible Coupled enzymatic assay... 

In heterogeneous assays the bound and free label forms must be separated by different means, such as precipitation of antibody or coupling of the antibody to a solid support. Heterogeneous immunoassays are more versatile as inclusion of a separation step eliminates most of the interferences before quantification. However, these assays are also more labor-intensive and time-consuming. Any of these methods can be performed in either competitive or non-competitive format. 

Lettieri, G.-L., Verpoorte, E., de Rooij, N.F., Affinity-based bioanalysis using freely moving beads as matrices for heterogeneous assays. Micro Total Analysis Systems, Proceedings 5th u7XS Symposium, Monterey, CA, Oct. 21-25, 2001, 503-504. 

A heterogeneous assay was developed by Kartalov and Quake for DNA sequencing-by-synthesis to reliably sequence up to four consecutive base pairs [374], Briefly, the... 

Heterogeneous or homogeneous immunoassays Certain assays require an additional method to remove unbound label (also termed free label) leaving bound label, and for a given assay these labelled components are either antibody or antigen, but not both. These assays are called heterogeneous assays, and common methods of separation include adsorption, precipitation, or commonly the use of a solid phase. In contrast, homogeneous assays do not require the removal of... 

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