Scanning Switch-off\nMicroscopy for Super-Resolution\nFluorescence Imaging

Super-resolution (SR) microscopy provides a revolutionary\noptical\nimaging approach by breaking the diffraction limit of light, while\nthe commonly required special instrumentation with complex optical\nsetup hampers its popularity. Here, we present a scanning switch-off\nmicroscopy (SSM) concept that exploits the omnipresent switch-off\nresponse of fluorophores to enable super-resolution imaging using\na commercial confocal microscope. We validated the SSM model with\ntheoretical calculations and experiments. An imaging resolution of\n∼100 nm was obtained for DNA origami nanostructures and cellular\ncytoskeletons using fluorescent labels of Alexa 405, Alexa 488, Cy3,\nand Atto 488. Notably, super-resolution imaging of live cells was\nrealized with SSM, by employing a dronpa fluorescent protein as the\nfluorescent label. In principle, this SSM method can be applied to\nany excitation laser scanning-based microscope.