Merocyanin 540

Merocyanin 540 is a fluorescent membrane probe that selectively stains the membranes of various electrically excitable cells but not non-excitable cells. Its maximum excitation wavelength Ex is 540nm and its maximum emission wavelength Em is 580nm^{[1, 2]}. Merocyanin 540 is an anionic lipophilic fluorescent dye that can be used as a photosensitizer in phototherapy of human cancer cells (leukemia)^{[3, 4]}. Merocyanin 540 can be used as an optical probe of cardiac transmembrane electrical activity^[5].

References:
[1] Easton T G, Valinsky J E, Reich E. Merocyanine 540 as a fluorescent probe of membranes: staining of electrically excitable cells[J]. Cell, 1978, 13(3): 475-486.
[2] Kulkarni R. Design and Application of Photoinduced-Electron Transfer-Based Voltage-Sensitive Dyes to Biological Imaging[M]. University of California, Berkeley, 2018.
[3] Williamson P, Mattocks K, Schlegel R A. Merocyanine 540, a fluorescent probe sensitive to lipid packing[J]. Biochimica et Biophysica Acta (BBA)-Biomembranes, 1983, 732(2): 387-393.
[4] Sieber F, Spivak J L, Sutcliffe A M. Selective killing of leukemic cells by merocyanine 540-mediated photosensitization[J]. Proceedings of the National Academy of Sciences, 1984, 81(23): 7584-7587.
[5] Salama G, Morad M. Merocyanine 540 as an optical probe of transmembrane electrical activity in the heart[J]. Science, 1976, 191(4226): 485-487.

Merocyanin 540是一种荧光膜探针，可选择性地染色各种电兴奋细胞的膜，但不染色非兴奋细胞的膜，最大激发波长Ex为540nm，最大发射波长Em为580nm^{[1, 2]}。Merocyanin 540是一种阴离子亲脂性荧光染料，能够在人类癌细胞（白血病）的光治疗中用作光敏剂^{[3, 4]}。Merocyanin 540能够作为心脏跨膜电活动的光学探针^[5]。