Fluorescent peptide nanoparticles, in every color of the rainbow

The discovery of green fluorescent protein (GFP), which is made by a jellyfish, transformed cell biology. It allowed scientists to stitch the GFP sequence to proteins from other organisms to trace their movements and interactions in living cells. Now, researchers have designed peptide nanoparticles that can each glow in a variety of colors, opening the door for many new biomedical applications.