The super resolution microscopy system Zeiss ELYRA PS provides two methods to substantially increase optical resolution: "superresolution structured illumination microscopy" (SR-SIM) and "photoactivated localization microscopy / direct stochastic optical reconstruction microscopy" (PAL-M/dSTORM).
SIM can double optical resolution in a sample in comparison to a confocal set-up, resulting in a vertical resolution of 100 nm and an axial resolution of 250 nm. SIM can be applied to fixed samples, stained with up to 4 fluorophores. The only prerequisites are a good signal-to-noise ratio and the use of high precision cover glasses.
Prerequisite for PAL-M is the use of photoactivatable or photoconvertable fluorophores like the fluorescenct proteins paGFP, Dendra and EOS. The related technique dSTORM can be applied to fluorophores like Alexa Fluor® 488, Alexa Fluor® 633, Cy3 and Cy5 in combination with special buffers to induce blinking of the fluorophores. The maximum resolution using PAL-M/dSTORM is 20 nm in x/y and 100 nm in z.
The ELYRA PS is equipped with laser lines at 405, 488, 561 and 642 nm, matching the excitation maxima of most commonly used fluorophores. At the detection site, for structured illumination an EM-CCD camera with 1002 x 1002 pixels for maximum resolution is used. For PAL-M/dSTORM applications, an EM-CCD with 512 x 512 pixels and high sensitivity is used.