Researchers in Zurich, Switzerland, are developing nanomagnets that could someday strip potentially harmful substances from the blood. The technology might be used to treat people suffering from drug intoxication, bloodstream infections, and certain cancers.

The project involves magnetized nanoparticles that are coated with carbon and studded with antibodies specific to the molecules the researchers want to purge from the blood: inflammatory proteins such as interleukins, or harmful metals like lead, for example. By adding the nanomagnets to blood, then running the blood through a dialysis machine or similar device, the researchers can filter out the unwanted compounds.

"The nanomagnets capture the target substances, and right before the nanoparticles would be recirculated, the magnetic separator accumulates the toxin-loaded nanomagnets in a reservoir and keeps them separated from the recirculating blood," explains Inge Herrmann, a chemical engineer at the University of Zurich who is leading the work.

According a study published in the journal Nephrology Dialysis and Transplantation in February 2011, the researchers were able to remove 75 percent of digoxin, a heart drug that can prove fatal if given in too high a dose, in a single pass through a blood-filtration device. After an hour and a half of cleansing, the nanomagnets had removed 90 percent of the digoxin.

One big caveat is that the researchers must demonstrate that the particles aren't toxic to the body and won't interfere with the blood's ability to clot. But early results are promising. In a 2011 paper in Nanomedicine, Herrmann's group showed that the nanomagnets did not damage cells or promote clotting—two critical safety milestones.

At the annual meeting of the American Society of Anesthesiologists in October, Herrmann presented data showing that the nanomagnets are partially taken up by monocytes and macrophages, two forms of immune cells. That's an important proof of principle for any future application of the technology in fighting serious infections.

Herrmann and her colleagues are now conducting a study of the technology in rats with sepsis—a severe bloodstream infection marked by the massive buildup of damaging immune molecules. Severe sepsis affects approximately a million people in the United States each year.