Used primarily as a chromogenic substrate in enzyme-linked immunosorbent assays (ELISA), it facilitates the detection of antibodies or antigens by producing a blue color upon oxidation. This color change, which can be quantified spectrophotometrically, makes it valuable in diagnostic applications for detecting diseases, pathogens, and biomarkers. Additionally, it is employed in immunohistochemistry for visualizing cellular components under a microscope. Its sensitivity and stability contribute to its widespread use in research and clinical laboratories for accurate and reliable results.