Super-resolution means resolution beyond the diffraction limit.
First you shine a lot of light which saturates most fluorophores, leaving very few active.
They you can observe fluorophores firing one by one. Their exact position is a bit stochastic and beyond the diffraction limit, but so long as there aren't to many in close proximity, you can wait for it to fire a bunch of times, and the center of the Gaussian is the actual location.
From this we see that super-resolution microscopy is basically a space-time tradeoff: the more time we wait, the better spacial resolution we get. But we can't do it if things are moving too fast in the sample.
Tradeoff with cryoEM: you get to see things moving in live cell. Electron microscopy fully kills cells, so you have no chance of seeing anything that moves ever.
Caveats:
  • initial illumination to saturate most fluorophores I think can still kill cells, things get harder the less light you put in. So it's not like you don't kill things at all necessarily, you just get a chance not to
  • the presence fluorophore disturbs the system slightly, and is not at the same Exact location of the protein of interest
Stefan Hell was really excited by this as of 2023.
Instead of shining a light over the entire sample to saturate it, you illuminate just a small bit instead.
He was basically saying that this truly brings the resolution to the actual physical limits, going much much beyond 2014 Nobel prize levels.
Figure 1. Illumination patterns for STED microscopy. Source.