Nanoscale separation of molecular species based on their rotational mobility

We combine far-field fluorescence nanoscopy through serialized recording of switchable emitters with polarization-sensitive fluorescence detection. In addition to imaging with nanoscale spatial resolution, this technique allows determination of the fluorescence anisotropy of each detected dipole emitter and thus an estimate of its rotational mobility. Subpopulations of fluorescent markers can thus be separated based on their interaction with the sample. We applied this new functional nanoscopy to imaging of living mammalian cells. (C) 2008 Optical Society of America