Single molecule fluorescence properties of NIR dyes.

The measured single molecule fluorescence properties of the two brightest NIR dyes tested, in each wavelength band. The mean number of photons per single molecule was calculated from the mean single molecule fluorescence intensity integrated over 250 ms. The laser power exiting the objective was ∼1.6 µWµm−2 for all dyes. The mean number of photons per single molecule, the mean period of continuous fluorescence emission and the mean duty cycle were obtained from the intensity traces of 74 Alexa 700, 276 IRDye 700DX, 99 Alexa 790 and 272 IRDye 800CW molecules.