Used as an electron acceptor in biological assays, particularly in cell viability and mitochondrial activity tests. It is commonly employed in tetrazolium-based assays, where living cells reduce the compound to form a colored formazan product, which can be quantified spectrophotometrically. This allows researchers to assess cell proliferation, cytotoxicity, and metabolic activity. Its ability to penetrate cell membranes and undergo enzymatic reduction makes it valuable in high-throughput screening and drug development studies.