Monday, December 22, 2008

Giant Magnetoresistance Now for Cancer Detection

Filed under: in the news...

Stanford scientists are developing a microchip device that uses the technology that makes hard drives work to detect cancer protein markers in blood.

The MIT Technology Review reports:

Wang's device takes advantage of giant magnetoresistance, a phenomenon that won its discoverers the 2007 Nobel Prize in physics. The device is built on a silicon chip arrayed with 64 magnetic sensors called spin valves. Each valve is coated with a different kind of antibody, a molecule primed to latch on to a particular cancer protein. When the chip is exposed to blood serum, the target proteins stick to the antibodies. Wang then adds a solution of magnetic nanoparticles, also attached to antibodies, that stick to the captured proteins. The magnetic field of the captured nanoparticles measurably changes the resistance of the underlying spin valve, allowing Wang to determine the concentration of cancer proteins in the serum.

In tests where the Stanford prototype scanned for cancer proteins, including a marker of colon cancer, it was two orders of magnitude more sensitive than the standard technique for detecting blood proteins, which uses a similar antibody capture sandwich in combination with fluorescent tags.

More from MIT Technology Review...

Image: A prototype scanner (top) detects cancer-specific proteins present in low concentrations in the blood by capturing them on magnetic sensors and tagging them with magnetic nanoparticles. The heart of the scanner is a silicon chip arrayed with magnetic sensors called spin valves (below). Credit: Sebastian Osterfeld (top); PNAS (bottom)

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