In chromogenic detection, a chromogen (a colorless substrate) is converted into a colored product through an enzymatic reaction. Commonly, enzymes like Horseradish Peroxidase (HRP) or Alkaline Phosphatase (AP) are conjugated to antibodies or other binding molecules. When these enzyme-conjugated molecules bind to their target antigens in tissue sections, the addition of a chromogenic substrate leads to a colored precipitate at the site of the antigen-antibody reaction.
