Worm Quantum Dot Factories

Not only do earthworms fertilize soil and help catch fish, but the wriggly creatures are also capable of manufacturing semiconductor nanoparticles called quantum dots, according to researchers at King’s College London (Nat. Nanotechnol., DOI: 10.1038/nnano.2012.232). Scientists have previously biosynthesized nanoparticles by hijacking the cellular machinery inside bacteria, viruses, and fungi, but “we’re pretty sure this is the first time this has been intentionally achieved in a higher animal,” says Mark Green, who led the research team. To prove the worms capable of the feat, Green, Stephen R. Stürzenbaum, and coworkers put the animals in soil laced with cadmium chloride and sodium tellurite. When they later cut the worms open, they found 2-nm-diameter CdTe quantum dots. The researchers think the earthworms sequester the heavy metals as part of a detoxification mechanism. After harvesting the worm-made dots, the team demonstrated their utility as imaging agents: The particles are taken up by ovarian cancer cells and emit green light after being excited at blue wavelengths.