Antibody in immunoassay

The application of conducting polymers such as polyaniline, polypyrrole, and polythiophene for immobilizing capture antibodies in immunoassay systems is widespread. 

V5. Voss, Jr., E. W., and Mummert, M. E., Anti-metatype antibodies in immunoassays. Mikrochim. 

The use of antibodies has allowed the development of a technique known as immunodiagnostics, especially attractive for the direct analysis of intrinsically complex samples such as blood, serum, urine, food, etc. An immunoassay is a test that uses antibody-antigen complexes as a means of generating a measurable result. The specific interaction between epitopes and paratopes lies at the heart of every immunoassay. The role of antibodies in immunoassays is based on the observation that, in a system containing the determinant and a specific antibody, the distribution of the former between its antibody-bound and antibody-free forms is quantitatively related to the total analyte concentration. 

In recent years, an increasing number of MIPs offering comparable affinities and cross-reactivity profiles to those of antibodies have been synthesised. Indeed, in 1993 it was demonstrated that imprinted polymers can be substituted for antibodies in immunoassay protocols [3]. The imprint-based assay was referred to as MIA (for... 

These matrices have been used as chromatographic stationary phases for both enantiomeric and stereoisomeric separations [8], as artificial antibodies in immunoassay-type analyses [7], as microreactors for stereoselective synthesis [9] and as catalysts [10,11] and equilibrium-shifters [12,13] for a variety of reactions. Since MIPs can be produced for such a wide variety of molecules, these characteristics have led many researchers to investigate the possibilities of employing MIPs as the... 

Recently, a strong trend in molecular recognition is the development of molecular imprinting polymers (MIP). MIPS have been used as synthetic antibodies in immunoassays and biosensors, but also as catalysts and separation media (employed both in analysis and extraction). One of the first applications of MIPs in separations was the enantiomeric separation of amino acids derivatives. 

Since immunoassays utilize antibodies as analytical reagents, the challenge is to obtain antibodies specific for an individual compound that may be present in a milieu of structurally related and unrelated compounds. Antibodies can be produced by in vivo immunization (polyclonal antibodies), hybridoma technology (monoclonal antibodies) and by genetically engineered bacteria (antibody fragments with affinities for specific molecules). Some caveats pertaining to the production and use of such antibodies in immunoassay procedures will be presented. 

Ismail, A.A. (2005) A radical approach is needed to eliminate interference from endoge nous antibodies in immunoassays. Clinical Chemistry, 51, 25 26. 

Molecularly imprinted sorbent assays represent one of the most typical applications of biomimetic use, where imprinted polymers are used as substitutes of natural antibodies in immunoassays. The assays usually involve competitive binding of an analyte with a certain quantity of labeled ligands, in which the labeled ligand unbound is proportional to the analyte added. Because dissociation constants of common imprinted polymers are around 10 6-10 9 M, competitive binding assays could easily be performed. In practice, many molecularly imprinted sorbent assays have been developed for biologically active compounds, including theophylline, diazepam [26], S-propranolol [27], morphine, Leu-enkephalin [28], cyclosporin A [29], yohimbine [30], methyl-a-glucoside [31], corticosteroid [32], atrazine [33, 34], and 2,4-D [35]. 

The potential advantages of MIPs as replacements for biological antibodies in immunoassays include... 

Molecular imprints A template is prepared in such a way that certain selected compounds interact with it, based on steric and chemical memory. They are analogous to antibodies in immunoassays, where they can also be used in competitive assays. Molecular imprints have been used in LC and CE. 

Lan E.H., Dunn B., Zink J.I. Sol-gel encapsulated anti-trinitrotoluene antibodies in immunoassays for TNT. Chem. Mater. 2000 12 1874-1878... 

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