An inexpensive biosensor that detects glucose in saliva, tears and urine could one day replace pinpricks for diabetes testing. ”Most sensors typically measure glucose in blood,” says Jonathan Claussen, a former doctoral student at Purdue University (West Lafayette, Indiana, USA) and currently a research scientist at the US Naval Research Laboratory. “Many [sensors] in the literature weren’t able to detect glucose in tears and saliva. What’s unique is that we can sense in all four different human serums: saliva, blood, tears and urine. That has not been shown before,” Claussen explains on the Purdue University website.
A press release on the site explains how the sensor works. The device is composed of layers of nanosheets resembling tiny rose petals made of graphene, a single-atom-thick film of carbon, platinum nanoparticles, and an enzyme glucose oxidase. Each petal contains a few layers of stacked graphene. The edges of the petals have dangling, incomplete chemical bonds, defects where platinum nanoparticles can attach. Electrodes are formed by combining the nanosheet petals and platinum nanoparticles. Then the glucose oxidase attaches to the platinum nanoparticles. The enzyme converts glucose to peroxide, which generates a signal on the electrode.
The technology could be modified to test for medical conditions simply by swapping enzymes. Claussen gives the example of replacing the enzyme glucose oxidase with glutemate oxidase to test for Parkinson’s.
Claussen and Purdue doctoral student Anurag Kumar led the project, working with Timothy Fisher, a Purdue professor of mechanical engineering; D. Marshall Porterfield, a professor of agricultural and biological engineering; and other researchers at the university’s Birck Nanotechnology Center. A research paper has been published in Advanced Functional Materials.