Probes made of silicon currently are used to study brain function and disease but may one day be used to apply electrical signals that restore damaged areas of the brain. A major drawback to these probes, however, is that they cause the body to produce scar tissue that eventually accumulates and prevents the devices from making good electrical contact with brain cells called neurons, said Thomas Webster, an assistant professor of biomedical engineering.

New findings showed that the nanotubes not only caused less scar tissue but also stimulated neurons to grow 60 percent more fingerlike extensions, called neurites, which are needed to regenerate brain activity in damaged regions, Webster said.

The findings are detailed in a paper appearing this month in the journal Nanotechnology, published by the Institute of Physics in the United Kingdom. The paper was written by Webster, Purdue doctoral students Janice L. McKenzie and Rachel L. Price, former postdoctoral fellow Jeremiah U. Ejiofor and visiting undergraduate student Michael C. Waid from the University of Nebraska.

The nanotubes were specially designed so that their surfaces contained tiny bumps measured in nanometers, or billionths of a meter. Conventional silicon probes do not contain the nanometer-scale surface features, causing the body to regard them as foreign invaders and surround them with scar tissue. Because the nanometer-scale features mimic those found on the surfaces of natural brain proteins and tissues, the nanotubes induce the formation of less scar tissue.

The scar tissue is produced by cells called astrocytes, which attach to the probes. The Purdue researchers discovered that about half as many astrocytes attach to the nanofibers comp
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Contact: Emil Venere
venere@purdue.edu
765-494-4709
Purdue University
7-Jan-2004