immunodetection

Immunodetection is a family of laboratory techniques that identify and measure specific biomolecules using the binding between antigens and antibodies. In these assays, a target molecule in a sample is captured by a specific antibody, and the resulting complex is detected with a labeled secondary antibody or a reporter system. The signal, which may be enzymatic, fluorescent, or chemiluminescent, provides qualitative or quantitative information about the target's presence and abundance.

Common formats include ELISA (enzyme-linked immunosorbent assay), Western blotting, immunohistochemistry, immunocytochemistry, immunofluorescence, and rapid lateral flow assays. ELISA and Western blotting report soluble antigens or antibodies in a sample; immunohistochemistry and immunofluorescence localize targets within cells or tissue sections; lateral flow assays enable point-of-care testing.

Applications span clinical diagnostics (infectious diseases, autoimmune conditions, cancer markers), biomedical research, and quality control in food, veterinary, and environmental sectors. Immunodetection can be quantitative when calibrated with standards, or qualitative for presence/absence decisions.

Key considerations include antibody specificity and affinity, cross-reactivity, blocking and washing conditions, sample preparation, and appropriate controls. Assay limits of detection, dynamic range, and potential matrix effects influence interpretation. False positives and negatives can arise from non-specific binding, improper storage, or degraded reagents.