Glucose-monitoring material can use saliva, tears, urine

A new material for glucose monitoring can detect minute levels from saliva, tears and urine, promising yet another way to eliminate finger pricks for diabetics.

The research from Purdue University's Birck Nanotechnology Center and the U.S. Naval Research Laboratory is published in the journal Advanced Functional Materials. Though previous ways to monitor glucose using saliva have been found, the researchers say this is the first to be able to use the four body fluids.

The new biosensor requires fewer processing steps to produce than many nanomaterials, raising the possibility that it can be manufactured at a low cost, according to an article from Purdue.

The sensor has three main parts: layers of stacked graphene that resemble rose petals, platinum nanoparticles and the enzyme glucose oxidase. There are incomplete chemical bonds at the petal edges, where the platinum nanoparticles attach to form electrodes. Then the glucose oxidase attaches to the platinum nanoparticles, converting glucose to peroxide, which generates a signal on the electrode.  

The new technology is far more sensitive than previous biosensors based on graphene or graphite, carbon nanotubes and metallic nanoparticles, according to Jonathan Claussen, one of the project leaders. And it can distinguish between glucose and other compounds that often cause interference in sensors

The technology could be used beyond diabetes testing, Claussen said.

"Because we used the enzyme glucose oxidase in this work, it's geared for diabetes," Claussen said. "But we could just swap out that enzyme with, for example, glutemate oxidase, to measure the neurotransmitter glutamate to test for Parkinson's and Alzheimer's, or ethanol oxidase to monitor alcohol levels for a breathalyzer. It's very versatile, fast and portable."

Previously, Brown University researchers reported development of a biochip that can detect glucose from saliva by measuring light waves, rather than fluids or chemical compounds.

A mobile testing kit developed at Rice University also relies on saliva to detect protein markers indicating serious conditions including cancer, heart disease and HIV.

Meanwhile, University of Washington researchers have developed contact lenses that can  detect glucose levels in the fluid around the eye.

In yet another attempt to end finger pricks, a new smartphone add-on device from Northeastern University in Boston reads the fluorescence of nanosensors--injected like a tattoo just under the skin--to monitor a patient's glucose levels.

To learn more:
- here's the abstract
- read the Purdue article

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