Quantum dots allow communication with, perhaps control of, brain cells

An article in EE Times ("Scientists activate neurons with quantum dots", by R. Colin Johnson, 6 December 2001) describes research by scientists led by Christine Schmidt, an assistant professor of biomedical engineering at the University of Texas-Austin to use quantum dot devices to selective electrical contacts to neurons. According to the article, by selectively coding peptides that coated quantum dots, University of Texas scientists precisely controlled the spacing of hundreds of quantum dots on the surface of the living neurons. The cadmium sulfide contacts act as photodetectors, allowing researchers to communicate with the cells using precise wavelengths of light.

The research has some . . . interesting implications:

In this new biological application, attaching quantum dots directly to cells eliminates the need for external electrodes. The procedure is entirely non-invasive, similar to the use of fluorescent dyes to mark cells. And since molecular recognition is used, it is a "smart" technology that can pick precisely which capability will be controlled on each neuron to which a quantum dot is attached. Taken to the logical extreme, biologists could remotely control any neural function by activating select neurons.

"Presumably, in the future we will be able to turn on an ion channel or turn off something else," said Schmidt. "We could have highly regulated activity in the neuron. . . . One idea is to put a quantum dot right next to a protein channel ó one that opens and closes ó allowing ions to go in and out, and basically control the ion exchange, which in turn controls action potentials [neuron 'firing']. These are the electrical signals with which the neuron interacts with the brain."

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