Article

Microscopy allows us to make journeys to the microcosm or even the nano world. Techniques advance at a fast pace nowadays, and scientists can observe live specimens or fixed samples in greater and greater degree of detail on different levels, starting from the level of whole organisms, and going down to the level of tissues, cells, subcellular structures and even single molecules. In order to observe the molecular organization of very tiny structures, like microtubules, and to break with current resolution limits, scientists at the MPI-CBG together with colleagues from the Freie Universität Berlin combined two existing microscopy techniques into a new one. They merged stimulated emission depletion (STED) microscopy, a fluorescence microscopy technique that overcomes the diffraction limit of light microscopy and creates super-resolution images by deactivating selected fluorophores, with the recently developed expansion microscopy (ExM). ExM is a sample preparation tool that expands and increases the size of small biological structures by introducing polymers into the sample. 

The newly developed microscopy technique is called expansion stimulated emission depletion microscopy (ExSTED) and offers an increase in resolution of up to 30-fold compared to conventional microscopy. The researchers were able to observe structures even tinier than 10 nanometers with ExSTED.  This exciting new technique provides a model for super-resolution microscopy of entire cells in the ten-nanometer range. The results are published in the current issue of the journal ACS Nano.