Credit: UC San Diego.

Some nanomaterials can ferry cancer drugs to tumors; others can act as bright contrast agents for infrared or magnetic-resonance imaging.

While researchers are working to make these materials even more efficient tumor targeters and imaging agents, they will also need to make sure they are safe. But until now, "there has been little effort to engineer the self-destruction [of nanomaterials]...into non-toxic, systemically-eliminated products," write researchers in this week's issue of Nature Materials.

The nanoparticles haven't been tested in clinical trials yet, but there is good reason to suspect they'll be harmless in people. For one thing, earlier this month researchers presented results at the American Association for the Advancement of Science meeting of a gene expression study demonstrating that exposing human immune cells to silica particles with a range of different surface areas didn't harm the cells. And the researchers felt comfortable enough to expose themselves for the above photo, which shows the nanoparticles emitting fluorescent light under UV.