Immunoassays are a valuable tool in industry and the life sciences. These tests are to thank for better disease treatments, safer food and water and advances in biological research. In this guide, we will delve into immunoassays, explaining what they are, the different types and their applications.
What is an immunoassay?
An immunoassay is a test that relies on biochemistry to measure the presence and/or concentration of an analyte. The analyte can be large proteins, antibodies that a person has produced as a result of an infection or small molecules. These assays are highly adaptable and can be applied to many formats depending on the needs of the end user. The principle component of an immunoassay designed to detect a specific analyte, such as influenza nucleoprotein, are the antibodies that have been carefully selected to ensure the detection of the analyte at low concentration with high specificity, meaning will not react with similar antigens. The second feature of an immunoassay is the system that is designed to detect the binding of the specific antibody to the target analyte. Originally the signal from an immunoassay resulted from an enzyme acting on a substrate to yield a colored solution with the amount of color in the solution being equivalent to the amount of antigen in the test solution.
More recently the many complex steps of an immunoassay have been compressed into a simplified format for the end user. The format is dependent on the flowing of the specimen together with the assay components through a nitrocellulose test strip. In this format, binding of the antibody to the target antigen is directly observable by the user due to the accumulation of dyed microbeads that will bind to a specific location on the nitrocellulose yielding a colored line that is easily observable by the user (if the target analyte is present in the specimen).
Immunoassays today are designed in many formats depending on the target analyte and the needs of the end user. They can also be used to detect target analytes in a wide range of sample types including serum, plasma, whole blood, urine, or swabs of nasal passages, throat or urogenital tracts.
Quidel offers a continuum of diagnostic immunoassays including ELISAs, visually read rapid lateral flow tests and fluorescent immunoassays that are placed in an analyzer that automatically measures the fluorescent signals, interprets the data, and immediately displays the result on its screen. Quidel immunoassays accommodate the needs of differing healthcare settings from the physician office laboratory to hospital bedside, emergency departments and reference labs.
What are the applications of immunoassays?
Immunoassays are easy to perform, and as such, they are widely used. Here are some common immunoassay applications.
Clinical diagnostics and drug monitoring
One of the fields for which immunoassays are essential is disease diagnostics and treatment. For instance, immunoassays are used in cancer diagnostics, pregnancy tests and therapeutic drug monitoring. These bioanalytical tests can examine the response to pharmaceutical drug treatments for conditions like HIV and cancer. They’re also used in workplace drug-testing.
Biopharmaceutical drugs are those that have been extracted, synthesized or manufactured from or in a biological source. Immunoassays are valuable tools used in biopharmaceutical research and development, including vaccines and gene and cell therapy.
Immunoassay is widely used in food production and development to detect dangerous contaminants or allergens. For instance, immunoassay tests can look for gluten, toxic chemicals, heavy metal contamination, or pathogens like E. coli.
More recently, immunoassays have entered the environmental realm. Immunoassay technology is employed to detect contaminants in the environment. For instance, immunoassays test for certain pesticides, PCBs (polychlorinated biphenyls), and other toxic compounds in surface and ground water.
What are the advantages of immunoassay tests?
Immunoassay tests are widely used thanks to their many advantages. Immunoassays are:
Capable of detecting low levels of molecules
Useable for a wide range of compounds and applications