Early-stage tumors are often too small to see with magnetic resonance imaging (MRI). Now, a team of researchers has developed magnetic "nanoworm" particles that can circulate for a day in the bloodstream and home in on tumors, helping to enhance an MRI image. The nanoworms could make it easier to image small tumors, allowing cancer to be detected and treated earlier.

The research is part of a broader effort to treat cancer more effectively by delivering drugs and imaging agents directly to diseased cells using nanoparticles. But the challenge has been to create delivery vehicles that will circulate in the body long enough to find their way to a tumor in order to do their job. "You're always fighting a battle with the body's own rejection systems--the natural systems that try to get rid of any foreign body, such as a nanoparticle," says Michael Sailor, a professor of chemistry and biochemistry at the University of California, San Diego.

One option is to chemically treat the nanoparticles so that they're not recognized by the body's immune system. But increasingly, researchers are also tailoring the nanoparticles' shape to help them slip by defenses. The nanoworms created by Sailor and his colleagues consist of spherical iron oxide nanoparticles linked together so that they resemble the segments of an earthworm. The nanoworms are about 30 nanometers in length and are coated with a sugar called dextran that helps them evade the body's rejection system. The shape also helps. Previous studies have shown that particles with an elongated shape are not eaten up by phagocytes, immune cells responsible for clearing such particles from the body, as readily as spherical ones are.   Read More...