immunoassayid

An immunoassay is a laboratory technique used to detect or quantify substances, such as proteins, peptides, hormones, or antibodies, by exploiting the specificity of the immune system's response. These assays rely on the binding interactions between antigens (foreign substances) and antibodies (immune system proteins) to measure target analytes with high sensitivity and specificity. Immunoassays are widely applied in clinical diagnostics, research, and biotechnology due to their ability to detect very low concentrations of biomolecules.

The basic principle of an immunoassay involves the use of labeled antibodies or antigens that bind specifically to the target molecule. When the labeled molecule interacts with the target, a detectable signal—such as fluorescence, chemiluminescence, or color change—is generated, allowing for quantification. Common types of immunoassays include enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA), and lateral flow assays (e.g., pregnancy tests).

ELISA is one of the most widely used formats, where an enzyme-linked antibody binds to the target antigen immobilized on a solid surface. After washing away unbound components, a substrate is added that reacts with the enzyme, producing a measurable signal. RIAs, though less common today due to radiation concerns, were historically significant for their high sensitivity, using radioactive isotopes for detection. Lateral flow assays provide a rapid, point-of-care method, often used in home testing kits.

Immunoassays are valued for their versatility, as they can be adapted for various applications, including the detection of infectious diseases (e.g., HIV, COVID-19), drug screening, and biomarker analysis in cancer or autoimmune disorders. However, they require careful optimization to minimize false positives or negatives, as cross-reactivity or non-specific binding can affect accuracy. Advances in technology, such as the use of nanoparticles or microfluidic devices, continue to improve assay performance and expand their potential uses.