NaYF4 Doped with Lanthanides (IMAGE) DOE/Lawrence Berkeley National Laboratory Caption Researchers at Berkeley Lab's Molecular Foundry created upconverting nanoparticles from nanocrystals of sodium yttrium fluoride doped with ytterbium and erbium that can be safely used to image single proteins in a cell without disrupting the protein's activity. Credit Image by Andrew Mueller, Berkeley Lab Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.