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From antibodies to signals: How do immune tests detect the magic of biomolecules?
Immunoassay is a biochemical detection method that measures the concentration of large or small molecules (usually proteins) present in a solution and detects them through antibodies or antigens. These measured molecules are called "analytes". In biological fluids such as serum or urine, such tests are widely used in medical and research fields and have become an indispensable tool.
“The key to immune testing is the ability of antibodies to recognize and bind to specific macromolecules, thereby forming a signaling response.”
The principle of immunoassay testing relies on the binding of antibodies to specific antigens. Antigens are molecules that antibodies bind to, and antibodies are proteins produced by the body's immune system. When an antibody binds to its corresponding antigen, the reaction triggers a measurable signal that helps us determine the presence and concentration of a specific molecule.
History of immune testing
The concept of immunoassay testing dates back to the 1950s, pioneered by Rosalyn Sussman Yalow and Solomon Berson. Yalow won the Nobel Prize in 1977 for her work on immune testing, becoming only the second American woman to win the prize. With the development of technology, immunological testing methods have gradually been simplified, especially the introduction of enzyme labeling technology, making it more popular. In 1983, Professor Anthony Campbell replaced radioactive iodine in the test with a chemiluminescent label, making this test rapidly popularized in clinical testing around the world and promoting wider application.
How immunity testing works
In immunological tests, the antibody or antigen is usually linked to a detectable label. These labels can be enzymes, radioactive isotopes, DNA probes or fluorescent probes, etc. Appropriate labels will be selected according to different applications.
“Many modern immunoassays utilize chemiluminescence or other detection methods that can effectively identify and quantify antigens.”
Types of tags
Immunotests can be divided into several categories according to the markers used, the most common ones are enzyme immunoassay (EIA), radioactive immunoassay (RIA) and DNA reporter markers. Among them, enzyme immunoassay tests use enzymes to produce observable color changes in specific reactions. Radioactive labels, which detect radioactive radiation to determine the concentration of analytes, have been phased out due to safety concerns.
Format and classification of immune tests
Immunity tests can take many forms, classified according to how they are performed and the type of reaction. These include competitive immune tests, non-competitive immune tests, etc.
“Whether competitive or non-competitive, immunoassays accurately quantify analytes in samples.”
Practical application
Immunotesting has a wide range of applications in clinical medicine, especially playing a key role in disease diagnosis and monitoring. For example, many home pregnancy tests are based on the principle of immune testing and detect beta-human chorionic hormone (hCG) to determine pregnancy. In sports anti-doping testing, immunity tests are also used to check athletes' blood samples to ensure the fairness of competition.
Uses in research fields
In addition to clinical applications, immune testing also plays an important role in scientific research. For example, photoacoustic immunoassays are a new development that analyze by detecting low-frequency sounds produced by metal nanoparticle labels, which show great potential for rapid detection.
Overall, the development and innovation of immune testing has attracted biomedical attention. It has not only changed the way of disease diagnosis, but also promoted the birth of new technologies. What changes and possibilities will this field bring in the future?
