Earthworms roped into making quantum dots

Mark Green at King's College London got earthworms to manufacture cadmium telluride quantum dots.

Ordinary earthworms are proving to be a sophisticated chemistry lab: they can put together substances with unusual light-emitting properties. It is the first time organisms other than fungi and bacteria have been seen to do this.

Green knew that placing thiols - sulphur-containing groups of atoms - on water-soluble cadmium telluride dots made them more luminescent. When he learned that earthworms produce thiols that bind to metal atoms, he wondered whether worm-made quantum dots were a possibility.

Green got together with colleagues studying how earthworms process cadmium in contaminated soil that they eat. The team exposed the worms to cadmium chloride and sodium tellurite, and found that they moved the metals to their chloragogen cells - their equivalent of the liver.

After 11 days, the researchers removed the chloragogen cells, put them in water and exposed the mixture to a UV lamp. They found that it glowed green. To Green, that characteristic behaviour meant only one thing: "It said to me it was cadmium telluride quantum dots," he says. Observations with an electron microscope showed that he was right (Nature Nanotechnology, doi.org/j4c). What's more, the dots were able to light up cancer cells in an imaging experiment.