ELISA applications

AP is the second most popular choice for antibody-enzyme conjugation, being used in almost 20 percent of all commercial enzyme-linked assays. Although P-gal and GO are used frequendy in research and cited numerous times in the literature, their utilization for commercial ELISA applications represents less than 1 percent of the total assays available. 

For typical ELISA applications, a rather narrow detection window is observed, limited by the linear signal increase in the middle of the sigmoid enzymatic response curve. In contrast, IPCR revealed an extension of this linear detection range, often covering more than four decades of antigen concentration [26, 29, 36 38, 41, 66]. This additional quality of the IPCR... 

For any standard ELISA application requiring enhanced sensitivity in combination with almost complete retaining of all ELISA advantages, such as microplate format, common laboratory equipment and the immunological specificity for target antigens, however, Immuno-PCR is worth consideration. 

PBS/1%BSA, BSA used should be suitable for ELISA application (for example, Sigma Aldrich, cat. no. A7030). 

Gasc6n J, Oubina A, Barcelb D. (1997). Detection of endocrine-disrupting pesticides by enzyme-linked immuno-sorbent assay (ELISA) Application to atrazine. Trends in Analytical Chemistry 16 554-562. 

A wide variety of methods for purification are available. For most ELISA applications a purity approaching 95% may be sufficient to remove unwanted proteins. The method depends on the particular source material and its volume, and ultimately how much is needed. Techniques depend on fractional precipitation, electrophoretic, ion-exchange, ultracentrifugation, and affinity methods. 

Immunoassays designed for environmental applications are mostly sold as some variation of the ELISA format. ELISA-like formats dominate the field because they are inexpensive and because they provide high sensitivity and precision without requiring complex instrumentation. The basic ELISA format supports both field and laboratory-based applications but is limited by multiple steps and inadequate sensitivity for some applications, excessive variability and sometimes long analysis times. Some of the other formats discussed in this article may replace the ELISA for selected applications however, because many laboratories are familiar with the ELISA technology, there will be a significant delay before alternative formats are widely accepted. 

The rapid turnover rate of some enzymes allows ELISAs to be designed that surpass the sensitivity of radiolabeling techniques. In addition, substrates can be chosen to produce soluble products that can be accurately quantified by their absorbance or fluorescence. Alternatively, substrates are available which form insoluble, highly colored precipitates, excellent for localizing antigens in blots, cells, or tissue sections. The flexibility of enzyme-based assay systems makes the chemistry of enzyme conjugation one of the most important application areas in bioconjugate techniques. 

Gegg, C.V., and Ktzlcr, M.E. (1993) Directional coupling of synthetic peptides to poly-L-lysine and applications to the ELISA. Anal. Biochem. 210, 309-313. 

Starodub et al. [98] studied different constructions and biomedical applications of immunosensors based on fiberoptic and enhanced CL. They discussed three different approaches of immobilization of one of the immunocomponents on the fiberoptic surface. Good results could be achieved by the use of a special membrane closely connected to the fiberoptic, with sensitivities compared to that obtained by the ELISA method but with a faster rate of analysis. The sensor was... 

Although several immunochemical methods have been reported for LAS, few examples of their application to real environmental matrices have appeared. The first immunochemical method for LAS was reported by Fujita et al. [151]. It is a direct ELISA and uses MAbs generated against 5-sulfophenyl valeric acid conjugated to BSA through the carboxylic acid, thus preserving the sulfonic group... 

Immunochemical methods have been reported for both APEs and their metabolites, especially APs. A discussion of the immunochemical methodologies reported to date, the effect of the immunizing haptens employed, and the features of these techniques were recently reviewed [169]. Unfortunately, the detectability achieved is usually far from what is necessary for direct application to environmental samples. Moreover, the selectivity for APs versus APEs is not always satisfactory. Thus, Goda et al. [ 148] developed a direct ELISA for NP with a LOD of 10 pg L 1 and a working range between 70 and 1,000 pg L, but APEs with one to ten ethoxylate units are also well recognized. 

Regarding commercially available immunochemical kits, we could mention the Charm ROSA Enrofloxacin Test that detects ciprofloxacin and enrofloxacin equally (see Table 4) and the 5101ERFXlp test. This last one is a direct competitive ELISA, which uses MAbs and has a LOD of 3 ng g1 in tissues. Some other companies do have antibodies available as reagents for different applications such as Biodesign International and QED Bioscience Inc. 

PAMAM dendrimers or modified PAMAM dendrimers (with oxiamine or sulfhydryl surface functionalities) exclusive of one another. These antisera recognize den-drimers in ELISA (enzyme-linked immunosorbent assays), dot blots and Western blots. The immunogenicity of dendrimer-protein conjugates has implications for therapeutic use of dendrimers as vaccines and we anticipate that antidendrimer antibodies will have applications in patterning and assembling nanostructures containing dendrimers. 

Zajicek, J.L. Tillitt, D.E. Huckins, J.N. Petty, J.D. Potts, M.E. Nardone, D.A. 1996, Application of Enzyme-Linked Immunosorbent Assay (ELISA) for Measurement of Polychlorinated Biphenyls (PCBs) from Hydrophobic Solutions Extracts of Fish and Dialysates of Semipermeable Membrane Devices (SPMDs). In Environmental Immunochemical Methods, ACS Symposium Series 646 American Chemical Society Washington, D.C. Chapter 26, pp 307-325. 

Fukuda, N., Tanaka, H., and Shoyama, Y. (2000b). Applications of ELISA, Western blotting and immunoaffinity concentration for survey of ginsenosides in crude drugs of Panax species and traditional Chinese herbal medicines. Analyst 125,1425-1429. 

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