Immunoassay Reagents

Frequently Asked Questions:

What is an immunoassay?

Immunoassays measure analyte concentration via responses that are associated with antibody and antigens. Immunoassays are common procedures for measuring analytes usually occurring at below average concentrations that are unable to be determined precisely by other less expensive methods and procedures. Common uses of immunoassay methods include measurement of hormones, drugs, tumor markers, specific proteins and markers of cardiac trauma or injury.

How is an immunoassay performed?

Immunoassays operate in a variety of ways. They search high and low for molecules that are called "analytes." These molecules often are classified as being proteins. Learn more about how immunoassay tests work

What are the types of immunoassays?

There are five types of immunoassays that are generally used:

Enzyme Immunoassay (EIA):

One of the most commonly used types of immunoassays is EIA, which uses enzymes to label either the antibody or antigen. The most commonly used EIA methods for identification of infectious diseases is the enzyme-linked immunosorbent assay (ELISA).

Radioimmunoassay (RIA):

Radioimmunoassays determine antibody levels by using radioisotopes. An antigen is introduced to the radioisotope and the subsequent radioactivity of the antibody component is measured. With RIA, laboratory professionals can use just a single drop of blood to determine and measure the concentration of biochemical substances.

Fluoroimmunoassay (FIA):

FIAs are a type of immunoassays that utilize a fluorescent label or an enzyme label, which will then act on the substrate to form a fluorescent product. Fluorescent measurements are inherently more sensitive than colorimetric (spectrophotometric) measurements. Therefore, FIA methods have greater analytical sensitivity than EIA methods, which employ absorbance (optical density) measurement.

Chemiluminescent immunoassay (CLIA):

CLIAs utilize a chemiluminescent label. Chemiluminescent molecules produce light when they are excited by chemical energy. These emissions are measured by a light detector.

Counting Immunoassay (CIA):

Involves particle counting technology where latex particles are massed together by antigens or antibodies and are measured by scattered laser light while they are passed through a controlled sheath flow. This method is suitable for antibodies, antigens, haptens, and immune complexes.

Is PCR an immunoassay?

Polymerase chain reaction (PCR) tests are a different type of laboratory method that falls under the category of Molecular Diagnostics and are frequently used to detect HIV's genetic material, called RNA. These tests can be used to screen blood samples and to detect very early infections before antibodies have been developed.

Explore Surmodics IVD’s Molecular Diagnostics Products:

Surmodics IVD’s TRIDIA™ surface coatings optimize DNA, RNA, protein, and cell attachment for molecular diagnostic and immunoassay applications, reducing non-specific background and improving sensitivity. These versatile coatings bind molecules to a variety of surfaces and geometries and may be customized for selectivity using passivating polymers and reactive groups.

For diagnostic devices including point of care assays, Surmodics IVD’s surface coatings improve flow characteristics through membranes and microfluidic channels. Other (non-analyte capture) surfaces from Surmodics IVD increase the wettability.

Visit the link below to learn more about our molecular diagnostics products.

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