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Staff Accomplishments

Biosensor holds promise for faster, more accurate glucose readings for diabetics

June 2006
When dealing with long-term medical issues, patients shouldn't have to worry about the cost and the accuracy of the diagnoses. To help doctors and patients, researchers at Pacific Northwest National Laboratory are using nanotechnology to develop sensors that hold promise as an inexpensive and accurate tool for treating and managing diabetes, detecting lead poisoning in children, and signaling exposure to nerve agents. PNNL's new approach to biosensors is extremely sensitive and selective, effectively measuring glucose or other items of interest in the presence of body chemicals and medications, such as ascorbic acid and acetaminophen, that would normally interfere with glucose readings. Tiny carbon nanotubes make sensor selective and portable To create the glucose biosensor, the research team attached glucose oxidase enzymes to the tips of the nanotubes, which were grown from a chromium-coated material that acted as an electrode contact. The tips of the aligned carbon nanotubes protruded through an insulation layer, allowing them to come in contact with the sample. Sugar in the sample started a catalytic reaction with the enzymes, the energy from which was conveyed through the nanoelectrodes. The stronger the signal, the higher the sugar level. Principal investigator Yuehe Lin credits the sensor's success not only to the reactivity of the enzyme, but also to the high conductivity of carbon nanotubes, and the sensitivity of the nanoelectrode array. The biosensor's design exposes the most sensitive part of the carbon nanotube-the tip. The array holds about 1 million nanotubes integrated on a microchip electrode that measures 5 millimeters by 5 millimeters, or about the size of a raisin. This microchip sensor array has been integrated into a portable unit using PNNL-patented technology. Quick lead poisoning results for children The sensor's carbon nanotube design makes it one of the most sensitive approaches for detecting lead using a portable device. "Because lead ions are soluble in biological fluids and can be concentrated on the tips of carbon nanotubes by electrodeposition," Yuehe said, "the sensor has great potential to detect lead poisoning." Using this technology, lead poisoning in susceptible children and industrial workers could be detected in three minutes or less. Cholesterol and nerve agents just some of the other applications Because carbon nanotubes can be easily functionalized-enzymes, DNA or antibodies for molecular biorecognition can be attached to the nanotube tips-the biosensor has many other potential uses. It can be applied to sensors for other common health concerns, such as cholesterol or alcohol as well as environmental monitoring for pesticides, nerve agents, radioactive substances and toxic metal ions. Licensing opportunities available Currently available for licensing, these biosensors based on carbon nanotubes are applicable to detecting and identifying a broad range of health and environmental hazards for immediate response and mitigation. PNNL's sensors can be mass produced with high reproducibility from one sensor to another. Combining several arrays, each tuned for a specific type of chemical or biological agent, into a single miniaturized chip allows for quick and simultaneous detection of multicomponent agents. Contacts: Walter Weimer, Process and Measurement Technology Product Line Manager, or Ed Baker, Environmental Sustainablity Lead.

Page 802 of 1045

Energy and Environment

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