While other fluoride sensors exist, many of them cannot differentiate between fluoride and other anions negatively charged ions that might be present in the water.
"Although they can detect fluoride, they cannot accurately measure the levels of fluoride," Saha said. "Naked-eye detection of fluoride at different concentration levels is an advantage of NDI-based sensors. Our sensor relies on an electron transfer event from a fluoride ion to the NDI receptor for generating a visible response or signal, which in this case is color change. The electron transfer process can be reversed, and the sensor can be regenerated and reused over and over again."
By designing an appropriate sensor, Saha's laboratory has achieved a remarkable "nanomolar" sensitivity for fluoride, meaning it can detect about one ten-thousandth of a milligram of fluoride in a liter of water. This makes it one of the most sensitive fluoride sensors known to date.
Water fluoridation has been widely used in the United States since about 1960. Although often a subject of controversy, Saha says it has had the effect of improving overall dental health through a very basic chemical process. When added to water systems, fluoride reacts with a naturally occurring mineral, calcium phosphate, and produces a compound called fluorapatite. Fluorapatite then bonds with humans' teeth to form a hard, protective layer that wards off corrosion. This is important for dental health.
However, excessive amounts of fluoride in water can cause a condition known as dental fluorosis, especially in young children. This results in a mottled appearance of the dental enamel, as well as possible cracking and pitting of the teeth.
Fluoride is also used in several drugs prescribed to treat the brittle-bone disease osteoporosis. Given in the proper amounts, the fluoride appears to stimulate the formation of new bone tissue. However, when excessive amounts of fluoride build up
|Contact: Sourav Saha|
Florida State University