We have developed a novel fluorescent indicator for NO, DAR-M, which features long-wavelength excitation, high photostability and no pH dependency over a wide pH range.
Diaminofluoresceins are widely used for detection and imaging of nitricoxide (NO), but for biological applications, they have the disadvantages that the fluorescence of the fluorescein chromophore is pH-sensitive and overlaps the autofluorescence of cells. We have developed a membrane-permeable fluorescent indicator for NO based on the rhodamine chromophore, DAR-4M AM, which can be excited with 550-nm light