Tetranitroblue tetrazolium (TNBT) is widely used as a redox indicator in biochemical assays, particularly in histochemistry and microbiology. It is commonly employed to detect the presence of dehydrogenases and other enzymes in tissue samples, where it forms a colored formazan product upon reduction, making it useful for visualizing enzyme activity. In microbiology, TNBT is utilized in assays to study cellular respiration and metabolic activity in microorganisms. Additionally, it serves as a staining agent in gel electrophoresis to identify and quantify proteins or nucleic acids. Its sensitivity to reduction reactions makes it a valuable tool in research and diagnostic applications.