IIT Guwahati researchers develop advanced fluorescent sensor to detect cyanide

STAFF REPORTER

GUWAHATI: A research team at the Indian Institute of Technology (IIT) Guwahati, led by Prof. G. Krishnamoorthy from the Department of Chemistry, has developed a highly sensitive fluorescent sensor capable of detecting cyanide in water and human cells using only a UV light source. The sensor changes colour and emits bright fluorescence in the presence of cyanide, offering a powerful tool for environmental safety and forensic investigations.

Cyanide, a toxic compound commonly used in industries such as synthetic fibre production, metal cleaning, and gold mining, poses serious risks to human health and the environment. Even trace amounts can be lethal, making its early detection crucial.

Unlike many existing sensors that “turn off” when detecting target chemicals, this newly developed “turn-on” fluorescent chemosensor increases its brightness, significantly reducing the risk of false negatives. The sensor is based on the compound 2-(4'-diethylamino-2'-hydroxyphenyl)-1H-imidazo-[4,5-b]pyridine, which emits weak blue fluorescence under UV light. In the presence of cyanide, the fluorescence shifts to a bright cyan colour due to a specific chemical reaction.

The sensor demonstrated a detection limit of 0.2 µM in aqueous samples—far below the World Health Organization’s permissible limit of 1.9 µM in drinking water. It performed effectively in both river and tap water, with an accuracy range of 75–93%, and can be integrated into paper strips for portable testing.

“This sensor is versatile—it works in various real-world water samples and even within live biological cells,” said Prof. Krishnamoorthy, an expert in Molecular Fluorescence and Spectroscopy. “Its ability to be used in field testing and biomedical applications highlights its potential impact.”

The study also confirmed the sensor’s detection mechanism using a combination of laboratory experiments and advanced computational methods (DFT calculations). Additionally, the research revealed that the sensor could function like a basic logic gate, suggesting its potential for integration into smart sensor-based electronic devices.

The study, published in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, was conducted in collaboration with Prof. Bithiah Grace Jaganathan from the Department of Biosciences and Bioengineering, IIT Guwahati. Research scholars Ms. Mongoli Brahma, Mr. Arup Das Kanungo, Ms. Minati Das, and Mr. Sam P. Mathew contributed to the project.

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