Using “Nanoplug” Technology to Detect Blood Glucose

Originally Published MDDI May 2003

R&D DIGEST

In a novel application of nanotechnology, researchers are producing sensors with higher sensitivity levels and specificity than current devices. The highly efficient sensors could be used, for example, to measure blood glucose in diabetic patients. Specifically, the group has succeeded in implanting a gold nanoparticle with a diameter of 1.2 nm into the enzyme glucose oxidase. The gold nanoparticle acts like a minute electrical wire connecting the enzyme to an electrode—creating a gold “nanoplug.” The research was conducted by Itamar Willner, PhD, of the Hebrew University Institute of Chemistry (Jerusalem) and scientists at Brookhaven National Laboratory (BNL; Upton, NY). 

According to Jim Hainfeld, PhD, the BNL biologist who developed the technology, the concept involves measuring electrical current as an indicator of the number of biological molecules involved in a reaction. He says, “The gold nanoparticle plays two very important roles. First, it specifically orients the binding of the enzyme to the electrode so it's a very ordered attachment, not random. Second, since gold is a conductor, it provides an electrical path for the flow of electrons.”

Describing how the biosensor measure glucose levels, Willner explains that the enzyme glucose oxidase acts as an insulator when binding to a conductive surface such as an electrode. The nanoplug technology, however, facilitates the flow of electrons to the attached electrode and the oxidation of the glucose by the enzyme. The magnitude of the current reveals the extent of glucose in the system. 

Experimental results suggest that the technology yields more sensitive and specific blood glucose measurements than has been possible with existing techniques. The researchers also found that the enzyme-nanoparticle system was not affected by the presence of other substances that can interfere with accurate glucose readings, such as oxygen and ascorbic acid. 

The biosensor's increased sensitivity and specificity could improve the next generation of glucose-monitoring sensors, particularly those that measure glucose noninvasively.

The new technique is not limited to glucose detection, however. Says Hainfield, “Many other substances could be attached to electrodes in this way and used to sensitively and easily detect other biological molecules, such as bioterrorism agents or other disease markers.” The researchers speculate that the technology could also be used in implanted biofuel cells, which could provide electrical energy from blood sugar to operate heart pacemakers, insulin pumps, or prosthetic components. 

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