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Nanomagnets mimic drugs, sans side effects

Posted: 11 Jan 2008 ?? ?Print Version ?Bookmark and Share

Keywords:nanomagnets? pharmaceutical drugs? magnetic field?

Medical electronics has long been key to monitoring, diagnosing and predicting disease. Last year, however, electromagnetic fields were shown to cure cancer in rats, and this year magnetic fields were shown to reduce swelling after injuries. Now, biomedical engineers working with a physicist at Harvard University have demonstrated magnetic nanoparticles that can bind to the same cell receptors as do drugs and trigger the same effects in the presence of a magnetic fieldalbeit without the side effects of pharmaceuticals.

"We have harnessed a biological control system," said Don Ingber, a vascular biology specialist at the Children's Hospital in Boston, where most physicians hold a joint-appointment at Harvard University. "We can control it at will, using magnetic forces." Ingber performed the research in collaboration with Mara Prentiss, a Harvard University physicist, and Sanjay Kumar, a faculty member in Bioengineering at the University of California at Berkeley.

The noninvasive therapy marks the first time that magnetism has been used to control the biological processes normally managed by hormones. Dubbed "nanobiotechnology" by its inventors, the magnetic therapy gives medical doctors control of biological processes at the cellular level, which today is only possible by using pharmaceuticals that almost invariably have negative medical side effects.

The particles used in the study measured just 30nm in diameter, with a 5nm core, and were coated with antigens that can only bind to cell receptors that have specific antibodies. The nanoparticles remain dormant until activated by an external magnetic field, which causes them to cluster together, mimicking the effect of drugs, thereby triggering a cascade of biochemical signals inside the cell.

The specific cells tested by the medical researchers are called "mast" cells, which open pores in cells that allow calcium to flow inside. Because an influx of calcium can initiate signals traveling down nerves, the researchers hope to eventually use the technique to control physiological processes, such as heart rhythms and other muscle contractions. Because the metallic particles are paramagnetic, then can be magnetized and demagnetized over and over again, enabling the technique to be used in place of a physical pacemaker.

Next, the researchers plan to interface individual cells to external instruments that can use the magnetic fields to monitor and trigger complex biological processes with no physical connections to the body. For instance, a diabetic could trigger insulin production in his or her own body by stimulating their own internal gland, rather than taking a shot.

The military is interested in using magnetic nanobiotechnology to automatically trigger the production of antidotes inside the body of soldiers whenever they encounter a toxin or infectious disease. The Defense Advanced Research Projects Agency (Darpa) and the Department of Defense funded the research.

- R. Colin Johnson
EE Times

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