Scientists from Indiana University Bloomington are reporting in J. Am. Chem. Soc. the development of a fluorescent molecular probe that can detect minuscule concentrations of cyanide in water at normal pH levels. This research can conceivably be extended into a commercialization stage to develop a simple and cheap cyanide detector:
“This is the first system that works in water at normal pH levels and can be modified at will to enhance its reactivity,” said IU Bloomington chemist Dongwhan Lee, who led the research. “We are now looking at how to make the detector more sensitive.”
Graduate student Junyong Jo is the report’s first author.
One of the reasons the detector is not ready for market, Lee says, is that its optical properties need to be improved to emit light at longer wavelengths with less interference from background signals, especially those of biological origin. Since pond or river water is likely to contain living organisms and other organic matter, Lee says the detector system must be perfected.
Another unique aspect of the detector molecule is its modular structure.
“This is an essentially three-component chemical device with an activator, a receptor, and a reporter module,” Lee said. “These three components we can change at will in the future, either to make the detector more sensitive, or have it detect an entirely different toxin by sending out signals as different colors of light. Because of the structure’s modularity, a change in one of the three components doesn’t really affect the others.”
Lee and Jo were inspired by life itself — the natural properties of proteins — when they began designing their sensor molecule. The design of this novel system takes advantage of the structure-organizing “beta turn” motif commonly found in protein structures. The detector is essentially inert, except in the presence of cyanide, with which it preferentially reacts. The addition of cyanide induces a subtle but important structural change in the detector that turns it into a pigment that absorbs ultraviolet light (currently 270 nm) and convert it to light emission at around 375 nm, a purplish color at the very edge of human beings’ normal vision range.
Cyanide is a negatively charged ion composed of one carbon and one nitrogen atom. Among its many chemical targets inside cells is the oxidative phosphorylation system, which is a crucial producer of energy. Cyanide disrupts the system, making it impossible for cells to maintain even the most basic processes, which is one reason cyanide is considered a poison.
Abstract in in J. Am. Chem. Soc.: Turn-On Fluorescence Detection of Cyanide in Water: Activation of Latent Fluorophores through Remote Hydrogen Bonds That Mimic Peptide β-Turn Motif
Full story: Designer molecule detects tiny amounts of cyanide, then glows…