Homogeneous immunoassay based

Of particular interest is the development of homogeneous immunoassays based on cryptate 87 as label. They make use of a second, long range energy transfer... 

Homogeneous immunoassay based on resonant energy transfer... 

A. Homogeneous immunoassay based on marker-labeled antigen Ag Ag Ab... 

Homogeneous Immunoassay Based on Marker-Labeled Antigen... 

Homogeneous Immunoassay Based on Linkage of Plural Reactants... 

Patel, A. Campbell, A.K. Homogeneous immunoassay based on chemiluminescence energy-transfer. Clin. Chem. 1983, 29, 1604-1608. 

Recendy the authors have proposed a new homogeneous immunoassay based on electrochemical luminescence, 1 employing aronutic hydrocarbons such as pyrene as an electrochemically aedve label (141. The principle the proposed immunoassay is schematically... 

Figure 1. Principle of homogeneous immunoassay based on electrochemical immunoassay. In the presence of antibody the labeled antigen emits less photons due to the steric hindrance of antibody in electrodic reaction.

Fig. 14 Principle of a homogeneous immunoassay based of FRET technology (redrawn from Ref. [43])...

Abstract A significant number of immunochemical methods have been described for the determination of the most important emerging pollutants. The present chapter is a compilation of the information available today regarding immunochemical determination of industrial residues with a high potential risk of causing negative effects in the environment, wildlife, and public health. Homogeneous immunoassays, ELISAs, FIIAs, immunosensors, and selective immunoaffinity sample treatment methods have been reported for the analysis of an important number of these substances. The bases of these methods are briefly presented. 

Yamakawa Y, Ueda H, Kitayama A et al (2002) Rapid homogeneous immunoassay of peptides based on bioluminescence resonance energy transfer from firefly luciferase. J Biosci Bioeng 93 537-542... 

Kokko L, Sandberg K, Lovgren T, Soukka T (2004) Europium(III) chelate-dyed nanoparticles as donors in a homogeneous proximity-based immunoassay for estradiol. Anal Chim Acta 503 155-162... 

Homogeneous TR-FIAs have been reported in which proprietary lanthanide chelates are used. In a homogeneous immunoassay for T4, a fluorescent europium chelate coupled to thyroxine is quenched by antibody binding. 90 A similar approach is used for estrone-3-glucuronide. 91 TRFIAs based on homogeneous methods have not yet become widely used. 

The term homogeneous immunoassay may be defined as an immunoassay in which the extent of the antigen-antibody reaction can be determined without physical separation of the free and bound forms. This term is usually used for immunoassays such as enzyme and fluorescence immunoassays in which labeled substances (markers) are used. It does not include immunoassay systems such as nephelometry in which no labeled substances are used. Homogeneous immunoassays are widely used as routine tests because the procedures involved are simple. The principle of homogeneous immunoassay is based on changes in signals of the indicators by the antigen-antibody reaction (N5, U2). 

This method was developed by Collaborative Research Inc. (F3). The technique, based on the use of immunoreactive liposomes, may be classified as another type of homogeneous immunoassay. The liposomes are microscopic vesicles (200-1000 nm in diameter) consisting of a relatively impermeable lipid bilayer that delineates and separates an internal aqueous compartment from the external aqueous medium. The principle is as follows (Fig. 3 and Table 6). An enzyme, alkaline phosphatase, is encapsulated in the liposomes [E] and sequestered from the substrate, p-nitrophenyl phos-... 

Alternatively, Briggs et al. (B4) reported a fluorescent immunoassay based on the correlation of fluctuations in particle number measures of the amount of tagged species bound to micrometer-sized beads. A homogeneous competitive assay based on this principle can detect 1 ng of gentamicin per ml from a total sample volume of 10 p.1. 

In the homogeneous immunoassays there is no separation step because they are based on a changing signal by formation of the immune complex. The first assay of this type was the EMIT method (enzyme-modulated immunoassay technology) described by Engvall et al. (1970). The main disadvantages of homogeneous assays are low sensitivity and a more pronounced susceptibility to interferences. 

Kato, N., and Caruso, F. (2005). Homogeneous, competitive fluorescence quenching immunoassay based on gold nanoparticle/polyelectrolyte coated latex particles. J. Phys. Chem. B 109 19604-19612. 

When foreign cells enter the human body they are captured by antibodies, which attach themselves to the cell membrane surface. Complement binds to these antibodies in a specific order, after which the target cells are lysed. Because the liposome bilayer is structurally similar to the cell wall, complement can be used to completely lyse antibody-bound liposomes. Attention has to be paid to the fact that although complement is specific, some liposomes are susceptible to complement lysis, without being bound to an antibody. Most liposome immunoassays are homogeneous complement-based assays. 

Another homogenous immunoassay for T4 uptake, based on CEDIA technology, uses the two inactive fragments EA and ED of 3-galactosidase. In this assay, serum TBPs compete with EA for binding to an ED-T4 conjugate. As the concentration of unsaturated TBPs increases, less ED-T4 reassodates with EA to form the active enzyme ... 

Fig. 118. Homogeneous electrode-based enzyme immunoassay. Fecp = ferrocene.

PL Khanna, TE Worthy. A recombinant protein-based homogeneous immunoassay. Am Clin Lab, Oct 14, 1989. 

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