From the National Science Foundation

Nanowires in blood vessels may help monitor, stimulate neurons in the brain.

Working with platinum nanowires 100 times thinner than a human hair--and using blood vessels as conduits to guide the wires--a team of U.S. and Japanese researchers has demonstrated a technique that may one day allow doctors to monitor individual brain cells and perhaps provide new treatments for neurological diseases such as Parkinson's.
Writing in the July 5, 2005, online issue of The Journal of Nanoparticle Research, the researchers explain it is becoming feasible to create nanowires far thinner than even the tiniest capillary vessels. That means nanowires could, in principle, be threaded through the circulatory system to any point in the body without blocking the normal flow of blood or interfering with the exchange of gasses and nutrients through the blood-vessel walls.

The team describes a proof-of-principle experiment in which they first guided platinum nanowires into the vascular system of tissue samples, and then successfully used the wires to detect the activity of individual neurons lying adjacent to the blood vessels.

Rodolfo R. Llins of the New York University School of Medicine led the team, which included Kerry D. Walton, also of the NYU medical school; Masayuki Nakao of the University of Tokyo; and Ian Hunter and Patrick A. Anquetil of the Massachusetts Institute of Technology.

"Nanotechnology is becoming one of the brightest stars in the medical and cognitive sciences," said Mike Roco, Senior Advisor for Nanotechnology at the National Science Foundation (NSF), which funded the research.

Already, the researchers note, physicians routinely use arterial pathways to guide much larger catheter tubes to specific points in the body. This technique is frequently used to study blood flow around the heart, for example.

Following the same logic, the researchers envision connecting an entire array of nanowires to a catheter tube that could then be guided through the circulatory system to the brain. Once there, the wires would spread into a "bouquet," branching out into tinier and tinier blood vessels until they reached specific locations. Each nanowire would then be used to record the electrical activity of a single nerve cell or small groups of them.

If the technique works, the researchers say, it would be a boon to scientists who study brain function. Current technologies, such as positron emission tomography (PET) scans and functional magnetic resonance imaging (fMRI), have revealed a great deal about how neural circuits process, say, visual information or language. But the view is still comparatively fuzzy and crude. By providing information on the scale of individual nerve cells, or "neurons," the nanowire technique could bring the picture into much sharper focus.

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