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Implantable sensor to enable long-term medical monitoring

Posted: 07 Nov 2013 ?? ?Print Version ?Bookmark and Share

Keywords:MIT? implantable sensor? nitric oxide? carbon nanotube?

A team of researchers at MIT has developed carbon nanotubes that detect nitric oxide (NO) can be implanted under the skin for more than a year. NO is one of the most important signalling molecules in living cells, carrying messages within the brain and coordinating immune system functions. In many cancerous cells, levels are perturbed, but very little is known about how NO behaves in both healthy and cancerous cells.

"Nitric oxide has contradictory roles in cancer progression, and we need new tools in order to better understand it," stated Michael Strano, the Carbon P. Dubbs professor of chemical engineering at MIT. "Our work provides a new tool for measuring this important molecule, and potentially others, in the body itself and in real time."

Until now, that is: Led by postdoc Nicole Iverson, Strano's lab has built a sensor that can monitor NO in living animals for more than a year. The sensors can be implanted under the skin and used to monitor inflammationa process that produces NO. This is the first demonstration that nanosensors could be used within the body for this extended period of time.

Such sensors, made of carbon nanotubes, could also be adapted to detect other molecules, including glucose. Strano's team is now working on sensors that could be implanted under the skin of diabetic patients to monitor their glucose or insulin levels, eliminating the need to take blood samples.

Carbon nanotubeshollow, 1nm-thick cylinders made of pure carbonhave drawn great interest as sensors. Strano's lab has recently developed carbon nanotube sensors for a variety of molecules, including hydrogen peroxide and toxic agents such as the nerve gas sarin. Such sensors take advantage of carbon nanotubes' natural fluorescence, by coupling them to a molecule that binds to a specific target. When the target is bound, the tubes' fluorescence brightens or dims.

Implantable sensor to enable long-term medical monitoring

Figure 1: Postdoc Nicole Iverson demonstrates the instrument used to measure the fluorescent signal from nanotube sensors that detect nitric oxide.

Strano's lab has previously shown that carbon nanotubes can detect NO if the tubes are wrapped in DNA with a particular sequence. In the paper, the researchers modified the nanotubes to create two different types of sensors: one that can be injected into the bloodstream for short-term monitoring, and another that is embedded in a gel so it can be implanted long-term under the skin.

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