The research team at the Indian Institute of Technology (IIT) Guwahati, led by Prof. G. Krishnamoorthy from the Department of Chemistry, has developed a highly responsive fluorescent sensor that can detect cyanide in water and human cells using only a UV light source.
What is cyanide?
Cyanide is a highly toxic chemical commonly used in various industrial processes such as synthetic fibre production, plastics, metal cleaning, electroplating, and gold mining.
Improper disposal of cyanide can lead to environmental contamination, polluting soil and water bodies. Even minimal exposure to cyanide can disrupt the body’s oxygen supply, causing serious health hazards or death.
Detecting even traces of cyanide is therefore beneficial in safeguarding both environmental and human health.
Also read: Google CEO Sundar Pichai responds to Microsoft CEO Satya Nadella's “dance” invite (startuppedia.in)
About the fluorescent sensor developed by IIT Guwahati
The developed sensor changes colour and emits bright fluorescence in cyanide's presence, offering a powerful tool for environmental safety, forensic investigations and medical diagnostics.
It has been successfully tested on samples including river water and breast cancer cells, and found to be compatible with portable paper strip-based testing.
The IIT Guwahati research team has developed a “turn-on” chemosensor based on a compound named 2-(4′-diethylamino-2′-hydroxyphenyl)-1H-imidazo-[4,5-b]pyridine, which emits a faint blue fluorescence under UV light. [Source: Deccan Chronicle]
In the presence of cyanide, the fluorescence deepens and changes to a cyan colour, indicating a chemical transformation in the sensor molecule. This reaction is highly specific to cyanide, especially in a carefully selected water-based solvent system.
The sensor reached a detection limit of 0.2 μM in aqueous samples, which is much lower than the World Health Organisation’s permissible limit of 1.9 μM for cyanide in drinking water and Indian cuisine.
Fluorescent chemosensors, which emit light when they interact with specific target molecules, are popular due to their simplicity, affordability, high sensitivity, and utility in biological systems.
While many existing sensors detect harmful substances by reducing fluorescence—a “turn-off” mechanism—a “turn-on” approach, where the signal brightens in the presence of a target, offers better clarity and reduces the likelihood of false negatives.
To establish the mechanism behind this detection, the researchers employed a combination of laboratory experiments and computational techniques known as Density Functional Theory (DFT) calculations.
According to Prof. Krishnamoorthy, an expert in molecular fluorescence and spectroscopy, “What sets this sensor apart is its versatility. The sensor works not only in lab-prepared solutions but also in real water samples such as river and tap water, with an accuracy of 75 to 93 per cent. It can be embedded into paper strips for easy, portable testing and has shown excellent performance in live cell imaging. In fact, we were able to detect cyanide within biological cells, demonstrating its strong potential for applications in environmental and forensic fields.”
Also read: ED arrests ex-UCO Bank chairman Subodh Goel in ₹6,210 Cr loan fraud (startuppedia.in)
/startuppedia/media/media_files/2025/05/20/nj0utl9H2OpCDzOcfYYG.jpeg)