Two-color nanoscopy

In the latest of a series of papers from his lab, Stefan Hell and researchers of the Max Planck Institute for Biophysical Chemistry in Germany detail an approach to microscopy that achieves a resolution of half the wavelength of light.¹ Their simulated emission depletion (STED) microscope works by discharging a 100 picosecond laser pulse at a molecular sample tagged with green fluorescent protein (GFP). As soon as the molecules fluoresce, a second laser pulse excites red-emitting fluorophores and further fine tune the final image. The process allows visualization of multiple objects only 20 nanometers apart.

“What drives this work is the availability of genetically encoded fluorophores, like GFP and its descendents,” says Dr. Steven G. Boxer, a member of the Faculty of 1000 and a chemistry professor at Stanford University. “Hell is using an approach that can offer great advantages in the context of live cell microscopy, looking deep...