UC San Diego researchers target tumors with tiny 'nanoworms'

Scientists at UC San Diego, UC Santa Barbara and MIT have developed nanometer-sized “nanoworms” that can cruise through the bloodstream without significant interference from the body’s immune defense system and—like tiny anti-cancer missiles—home in on tumors.

Their discovery, detailed in this week’s issue of the journal Advanced Materials, is reminiscent of the 1966 science fiction movie, the Fantastic Voyage, in which a submarine is shrunken to microscopic dimensions, then injected into the bloodstream to remove a blood clot from a diplomat’s brain.

Using nanoworms, doctors should eventually be able to target and reveal the location of developing tumors that are too small to detect by conventional methods. Carrying payloads targeted to specific features on tumors, these microscopic vehicles could also one day provide the means to more effectively deliver toxic anti-cancer drugs to these tumors in high concentrations without negatively impacting other parts of the body.

“Most nanoparticles are recognized by the body's protective mechanisms, which capture and remove them from the bloodstream within a few minutes,” said Michael Sailor, a professor of chemistry and biochemistry at UC San Diego who headed the research team. “The reason these worms work so well is due to a combination of their shape and to a polymer coating on their surfaces that allows the nanoworms to evade these natural elimination processes. As a result, our nanoworms can circulate in the body of a mouse for many hours.”

“When attached to drugs, these nanoworms could offer physicians the ability to increase the efficacy of drugs by allowing them to deliver them directly to the tumors,” said Sangeeta Bhatia, a physician, bioengineer and a professor of Health Sciences and Technology at MIT who was part of the team. “They could decrease the side effects of toxic anti-cancer drugs by limiting their exposure of normal tissues and provide a better diagnosis of tumors and abnormal lymph nodes.”

The scientists constructed their nanoworms from spherical iron oxide nanoparticles that join together, like segments of an earthworm, to produce tiny gummy worm-like structures about 30 nanometers long—or about 3 million times smaller than an earthworm. Their iron-oxide composition allows the nanoworms to show up brightly in diagnostic devices, specifically the MRI, or magnetic resonance imaging, machines that are used to find tumors.