Sensitivity of immunoassay

Grant, S., A. Porter, and W. Harris (1999). Comparative sensitivity of immunoassays for haptens using monomeric and dimeric antibody fragments. J. Agric. Food Chem., 47 340-345. 

Figure 5. Comparison of the sensitivity of immunoassay systems for the detection of ECP in hGH. Each point shown represents the mean response of twenty replicate determinations.

Sensitivity of immunoassays is largely conditioned by markers applied for conjugation with the antibody. Traditional immunodetection methods ELISA with radioactive markers (radioimmunoassay—RIA), enzymatic markers (enzyme immunoassays—El A), or fluorescent markers (fluoroenzyme immunoassays FEIA) are currently the most widely used techniques in laboratory analysis of allergens as well as in clinical studies for determination of general and specific IgE and other subclasses of immunoglobulines, e.g., IgG4 in the Immuno-CAP system (Samson, 2001 Duran-Tauleria et al., 2004 Lidholm et al., 2006). 

Immunometric methods find increasingly wide applications owing to their superiority and continuous improvements. One of the major advantages of immunometric methods is that they provide consumers with early information (prior to food consumption) on possible health hazards (allergenic characteristics) of specific food products. The sensitivity of immunoassays is largely dependent on the type of a compound subject to analysis (up to lOpg/mL of the analyte). 

EDgQ for the initial antithyroxine was 9.2 x 10 9 M and the values for the fractions were in the range (6.3-13.0) x 10 9 M. However, the clonotype antibodies with which the most sensitive assay could be achieved differed for different types of immunoassays i.e., fractions I and VIII for radioimmunoassay, fraction I for fluorescence immunoassay, and fractions II, IV, and VIII for enzyme immunoassay in these experiments. The sensitivities of immunoassays may be improved by using appropriate clonotype antibodies. 

Due to the high specificity and sensitivity of immunoassays, there are bioanalytical methods for the measurement of an analyte of interest, with little or without preconcentration or purification of the samples. The principle behind immunoassays is based on an interaction between an antibody and a corresponding antigen, and the detection of the specific interaction using radiolabels (247), enzyme, fluorescent and luminescent compounds (178, 179,181,183), electroactive markers (177,180, 228, 248), or nanomaterials (249-251). 

The majority of the papers cited above under the individual hormones contain experimental details of how to set up and use immunoassays to quantify these hormones in extracts of plant tissue. Additional procedures can be found elsewhere for auxins [102-105], cytokinins [106-108], abscisic acid [109-115] and gibberellins [116-120]. The sensitivity of immunoassays for most of the plant hormones is generally in the pmole range but occasionally, when high affinity antibodies (K3=10 lmol ) are available, analysis is possible at the fmol level. Using amplified ELISA assays sensitivity down to 200 amol (200 x 10 mol) has been claimed for abscisic acid [113]. 

Reliability of an immunoassay is essential to its success in the market. The consumer may then benefit from their use by being able to take timely action. The rapid advances in biotechnology and immunology over the past decade have made it possible to improve both the specificity and sensitivity of immunoassays. 

Sensitivity of immunoassays in solution Radial (Mancini) lOmgl ... 

In the past two decades, much effort was invested to detect and identify binding products of environmental or workplace contaminants with macromolecules such as DNA, RNA, and blood proteins. In this field of applications, MS-based ap proaches are competing with immunochemical approaches. For chemical struc ture characterization and positive identification purposes, MS is still superior, but in some cases MS detection is lacking the sensitivity of immunoassays or radiolabeling. 

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