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Updated: Jun 3, 2026

Highly Sensitive and Quantitative Detection of Proteins and Their Isoforms by Capillary Isoelectric Focusing Method
Published on: September 19, 2018
The use of enzyme-linked immunosorbent assays to quantitate proteins in biological functions
1Laboratory of Toxicology, National Institute of Environmental Health science, Research Triangle Park, NC.
Immunoassays are techniques for measuring the concentration or activity of a substance using immunological reactions. Several types of immunoassay are commonly used, including precipitation assays using antibody/antigen complexes, agglutination assays using coated erythrocytes or other particles, and radio-(RIA) and enzyme immunoassays. Multiple factors determine the best assay for a particular use, including sample concentration, technical difficulty, required precision, and availability of specialized equipment. The most sensitive assays are the radio- and enzyme immunoassays, however safety and environmental issues regarding the use of radioisotopes have limited the application of RIAs, and thus enzyme-linked immunosorbent assays (ELISA) tend to be the method of choice when sample concentration is a critical issue. The potential for robotic automation and the availability of inexpensive microplate dilutors, pipetors, and readers has allowed for the generation of highly reproducible results for large numbers of samples in an short time.
Immunoassays are techniques for measuring the concentration or activity of a substance using immunological reactions. Several types of immunoassay are commonly used, including precipitation assays using antibody/antigen complexes, agglutination assays using coated erythrocytes or other particles, and radio-(RIA) and enzyme immunoassays. Multiple factors determine the best assay for a particular use, including sample concentration, technical difficulty, required precision, and availability of specialized equipment. The most sensitive assays are the radio- and enzyme immunoassays, however safety and environmental issues regarding the use of radioisotopes have limited the application of RIAs, and thus enzyme-linked immunosorbent assays (ELISA) tend to be the method of choice when sample concentration is a critical issue. The potential for robotic automation and the availability of inexpensive microplate dilutors, pipetors, and readers has allowed for the generation of highly reproducible results for large numbers of samples in an short time.
Related Concept Videos
Enzyme-Linked Immunosorbent Assay
There are many different types of ELISAs, but they all involve an antibody molecule whose constant region binds an enzyme, leaving the variable region free to bind its specific antigen. Enzyme-substrate reaction allows the antigen to be visualized or quantified.
Western Blotting
The technique begins with separating proteins from the sample using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), followed by protein transfer, immunoblotting, and finally, protein detection.

