DNA-PAINT combined with total Internal Reflection Fluorescence (TIRF) microscopy enables highest localization precisions, down to single nanometers in thin biological samples. However, most cellular targets elude the accessible TIRF range close to the cover glass and thus require alternative imaging conditions, affecting resolution and image quality. In the presented work, we address this limitation by applying ultrathin physical cryosectioning of cultured cells in combination with DNA-PAINT. With “tomographic & kinetically-enhanced” DNA-PAINT (tokPAINT), we demonstrate the imaging of nuclear proteins with sub-3 nanometer localization precision, advancing the quantitative study of nuclear organization within fixed cells at the level of single antibodies. We believe that ultrathin sectioning combined with the versatility and multiplexing capabilities of DNA-PAINT will be a powerful addition to the toolbox of antitative DNA-based super-resolution microscopy for intracellular structural analyses of proteins, RNA and DNA in situ.
[more]
