A nanosensor to predict asthma attacks

Asthma is a common illness which affects at least 300 million people worldwide and which is responsible for about 200,000 deaths every year. But asthma attacks could be detected up to 3 weeks before they happen by testing regularly the breath of asthmatics. If the levels of nitric oxide increase, an attack might happen soon. Now, researchers at the University of Pittsburgh have created a nanosensor to warn about oncoming attacks. It can be encased into a handheld device that people blow into to determine the nitric oxide content of their breath. These sensors have only been tested in the lab, but human clinical trials are on the way, meaning that they might appear on the market in a few years -- and save lots of lives.

Asthma is a common illness which affects at least 300 million people worldwide and which is responsible for about 200,000 deaths every year. But asthma attacks could be detected up to 3 weeks before they happen by testing regularly the breath of asthmatics. If the levels of nitric oxide increase, an attack might happen soon. Now, researchers at the University of Pittsburgh have created a nanosensor to warn about oncoming attacks. It can be encased into a handheld device that people blow into to determine the nitric oxide content of their breath. These sensors have only been tested in the lab, but human clinical trials are on the way, meaning that they might appear on the market in a few years -- and save lots of lives.

A nanosensor to detect asthma attacks

Above is a diagram showing the essential parts of this nanosensor. You can see "a polymer coated nanotube field-effect transistor (NTFET) device containing random network of single-walled carbon nanotubes (SWNTs) between source and drain gold electrodes on SiO2 substrate." (Credit: Alexander Star research group).

This device was created by Alexander Star, a chemistry professor at the University of Pittsburgh and the members of his research group.

Here are some more details provided by the University of Pittsburgh. "The sensor consists of a carbon nanotube-a rolled, one-atom thick sheet of graphite 100,000 times smaller than a human hair-coated with a polyethylene imine polymer. Star cased the sensor in a hand-held device that people blow into to determine the nitric oxide content of their breath. The nitric oxide level in the breath of a person with asthma spikes as the airways grow more inflamed. High levels-perhaps two-thirds over normal-may precede an attack by one to three weeks, but possibly earlier depending on the asthma's severity, said Jigme Sethi, a Pitt assistant professor in the School of Medicine's Division of Pulmonary, Allergy, and Critical Care Medicine and a clinician at UPMC Montefiore, who plans to clinically test Star's sensor."

In "Pitt professor's invention may warn of asthma attack," the Pittsburgh Tribune-Review adds more explanations. "'If you're checking on a regular basis and you notice the levels climbing, you can increase your steroids and medication used to treat the asthma and maybe prevent an asthma attack,' said Jigme Sethi. Patients might be able to lessen the amount of medicine they take if their nitric oxide levels are low, he said."

Sethi added that it was previously not feasible for people affected with asthma to measure their nitric oxide levels at home because they needed expensive and bulky machines. But now, these nanosensors could allow people with asthma to watch their nitric oxide levels as easily as people with diabetes check their blood sugar with hand-held glucose monitors."

For more information, this research work has been published by Nanotechnology under the name "Carbon nanotube sensors for exhaled breath components" (Volume 18, Number 37, Article 375502, September 19, 2007). Here are two links to the abstract and to the full scientific paper (Free access for registered users, PDF format, 7 pages, 649 KB) from which the above diagram has been extracted.

So if you're suffering from asthma, here is some hope. But you'll still have to wait several years before using these nanosensors -- if they're approved by the U.S. Food and Drug Administration -- and other regulators.

Sources: University of Pittsburgh News, August 22, 2007; Allison M. Heinrichs, Pittsburgh Tribune-Review, August 22, 2007; and various websites

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