Prigozhin, M. B. et al. Nat. Nanotechnol. https://doi.org/10.1038/s41565-019-0395-0 (2019).

Electron microscopy (EM) is a powerful approach for imaging biological structures. However, the ability to label specific targets, such as proteins of interest, is limited owing to the relatively small number of tags that are suitable for single-molecule imaging or compatible with multiplexed imaging of multiple targets. One exciting possibility for multiplexed imaging comes in the form of cathodoluminescent probes, which emit light after excitation by an electron beam. Prigozhin et al. have developed lanthanide-based cathodoluminescent nanoparticles suitable for multiplexed EM. The researchers developed optimized synthesis protocols to develop sub-20-nm particles that use different lanthanides to emit in nine different colors with sharp emission spectra. They showed proof-of-principle multiplexed imaging experiments for their nanoparticles on a silicon substrate. These probes could find myriad uses in biological imaging applications.