Tiny Magnets Could Clear Diseases from the Blood

Blood cleaner: A microscope image shows one of the carbon-encapsulated nanomagnets used in the study.
Inge Herrmann

BIOMEDICINE

Tiny Magnets Could Clear Diseases from the Blood

Researchers make magnetic nanoparticles that can latch on to harmful molecules and purge them from the blood.

• BY ADAM MARCUS

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

The project involves magnetized nanoparticles 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. The researchers can filter out the unwanted compounds by adding the nanomagnets to blood and then running the blood through a dialysis machine or similar device.

"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 to a study published in the journal Nephrology Dialysis and Transplantation in February 2011, the researchers removed 75 per cent of digoxin. This heart drug can prove fatal if given 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 per cent 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 a necessary proof of principle for any future application of the technology in fighting severe infections.

Herrmann and her colleagues are now studying 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.    

Jon Dobson, a biomedical engineer at the University of Florida, says detoxification is "an exciting application" of nanotechnology. His group has been using magnetic nanoparticles as remote controls to manipulate cellular activity, such as the differentiation of stem cells. "With chemicals, it can be difficult to switch it off once the process starts. With magnetic technology, you can switch it on and off at will," Dobson says.

The potential uses of the Swiss group's method extend beyond sepsis to other diseases, including blood cancers, Dobson says. For example, it might be possible to design nanomagnets that pair up with circulating leukaemia cells and usher them out of the body, thus reducing the risk of metastasis.

O. Thompson Mefford, a nanotechnology expert at Clemson University, says the approach has appeal. He notes that the human body is a highly oxidative environment, and iron oxidation weakens the material's magnetic properties. By coating their magnets in carbon, the Swiss group may have devised a way to prevent this corrosion.

Still, he says, the technique's viability remains to be seen: "Having high circulation times, no immune response, and having the magnets not cluster with each other, that's a real challenge."