Immunoassays use biochemistry to detect an analyte’s presence or concentration, whether it is a protein, antibody or small molecule. These assays rely upon highly-specific antibodies to detect antigens at low concentrations with high specificity, reducing the possibility of off-target binding.
Detection is possible in many different sample types such as blood, serum & plasma, urine or bodily fluids.
ELISA (Enzyme-Linked Immunosorbent Assay) kits contain plates coated or uncoated with capture/detection antibodies. Their detection format can also vary; competitive and sandwich are two examples. Complementary techniques include PCR, RNA preservation, and DNA sequencing.
Western blotting allows detection of electrophoretically separated bands of protein via a specific primary antibody and a secondary antibody raised against the host of the primary antibody. The secondary antibody is commonly conjugated with a radiolabel, fluorophore or enzyme, such as horseradish peroxidase (HRP).
Immunoprecipitation utilizes antibodies attached to/able to attach to magnetic beads or agarose resin, which can then pull down proteins, RNA or chromatin (ChIP) out of solutions.