Merocyanin 540

Merocyanine 540 (MC-540) is an anionic, lipophilic sensitive fluorescent probe for membrane potential. It is a sodium salt of sulfonic acid, with a chain of four conjugated methine groups, a substituted benzoxazole ring at one end, and substituted thiobarbituric acid at the other end. MC-540 was originally developed as a photosensitizer for photographic emulsions. However, its main importance today is in biology and medicine. It is widely used as a biological probe in membrane studies (fluorescent probe for studies of membrane systems, optical probe for transmembrane potentials), for characterization of the multidrug resistance phenotype, for photo-induced cytotoxicity as a highly effective drug against human malignant cells (photodynamic purging of neoplastic cells in bone marrow explants - leukemia, treatment of lymphomas and metastatic neuroblastomas) and other diseases (malaria, Herpes simplex, HIV). MC-540 has been shown to be a selective stain for leukemic and immature hemopoietic cells in flow cytometry. Spectral Data: Ex/Em: 560/579nm (see Reference 10 for excitation of different solvents). MC-540 is spectrally similar to Alexa Fluor 546, Cy3 (Cyanine-3), Sulforhodamine B, TAMRA and Sulforhodamine B sulfonyl chloride.