Dental Tribune America

Researchers develop novel test to detect excess fluoride in water

By Dental Tribune International
December 27, 2019

EVANSTON, Ill., U.S.: Small doses of fluoride have been proven to promote oral health by strengthening tooth enamel and preventing dental caries. However, in some parts of the world, specifically across Africa, Asia and Central America, fluoride may occur naturally at levels that make it dangerous. Fluoride consumed in high amounts over long periods of time can cause skeletal fluorosis. To prevent this from happening, researchers have recently developed a test that does not require scientific expertise and can help detect dangerous levels of fluoride in drinking water.

“In the U.S., we hear about fluoride all the time because it’s in toothpaste and the municipal water supply,” said lead author Dr. Julius B. Lucks, associate professor of chemical and biological engineering at Northwestern University in Evanston. “It makes calcium fluoride, which is very hard, so it strengthens our tooth enamel. But above a certain level, fluoride also hardens joints. This mostly isn’t an issue in the U.S. But it can be a debilitating problem in other countries if not identified and addressed.”

Fluoride is a naturally occurring element that can flow out of bedrock into groundwater. It is particularly abundant in regions surrounding volcanoes and can be found in volcanic ash. The researchers tested the system both in the laboratory at the university and in the field in Costa Rica, near the Irazú volcano.

“Every test on these field samples worked,” Lucks commented. “It’s exciting that it works in the laboratory, but it’s much more important to know that it works in the field. We want it to be an easy, practical solution for people who have the greatest need. Our goal is to empower individuals to monitor the presence of fluoride in their own water.”

In the study, Lucks’ team freeze-dried the ribonucleic acid (RNA) reaction, which resembles a tiny cotton ball, and put it into a test tube with an accompanying small pipette. When placed in water, the pipette absorbs 20 µl, exactly what is needed to rehydrate the reaction. Although it currently takes 2 hours for the researchers to get the results, Lucks intends to accelerate the process in the near future.

Although the device is simple to use, the prepared test tube houses a sophisticated synthetic biology reaction. “RNA folds into a little pocket and waits for a fluoride ion. The ion can fit perfectly into that pocket. If the ion shows up, then RNA expresses a gene that turns the water yellow. If the ion doesn’t show up, then RNA changes shape and stops the process. It’s literally a switch,” he explained.

The study, titled “Point-of-use detection of environmental fluoride via a cell-free riboswitch-based biosensor,” was published online on Dec. 12, 2019, in ACS Synthetic Biology, ahead of inclusion in an issue.

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