New Sensor Can Measure Glucose in Saliva

Since patients with diabetes are required to test their glucose multiple times a day by pricking their fingers, less invasive methods for testing have long been sought out.

For this reason, researchers from Brown University have developed a new biochip sensor to measure glucose levels in saliva instead of testing levels in a patient’s blood.  
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“We have demonstrated the sensitivity needed to measure glucose concentrations typical in saliva, which are typically 100 times lower than in blood,” said Domenico Pacifici, PhD, the study’s lead researcher and assistant professor of engineering at Brown.

“Now we are able to do this with extremely high specificity, which means that we can differentiate glucose from the background components of saliva,” he said.

The sensor was created to use light, a metal surface, and a dye chemistry that changes color when exposed to glucose.

When light shines on the chip—a 1-inch-square piece of quartz coated thinly with silver etched with tiny slits and grooves on either side—a wave of free electrons in the silver are created from the grooves. Detectors measure the patterns from the interference of light and waves that pass by the grooves and slits.

Researchers then used a liquid mixture of water, salts, and enzymes—artificial saliva—on the chip to interact with the light and plasmon waves. Changes in glucose (a concentration of 0.1 micromoles per liter) were detected.

Pacifici and colleagues said that their next step will be to test their methods in human saliva and to create a portable device that allows those with diabetes to monitor their glucose levels.

Investigators note that they need to adjust for things like food and drink. A type of mouth rinse would need to be developed in order to keep saliva uncontaminated before testing occurred.

The complete study is published in the June issue of Nanophotonics. 

-Michelle Canales

References:

Siu VS, Feng J, Flanigan PW, et al. A “plasmonic cuvette”:dye chemistry coupled to plasmonic interferometry for glucose sensing. Nanophotonics. 2014 June [epub ahead of print] doi:10.1515/nanoph-2013-0057.

Brown University. Progress on detecting glucose levels in saliva [press release]. July 3, 2014. https://news.brown.edu/articles/2014/06/glucose. Accessed July14, 2014.