IIT, Guwahati, researchers develop fluorescent sensor to detect cyanide in water, human cells

New Delhi, May 19 (PTI) Researchers at IIT, Guwahati, have developed a highly responsive fluorescent sensor that can detect cyanide in water and human cells using only an ultraviolet light source, according to officials.

The sensor is claimed to be effective in real-world samples such as river water and breast cancer cells and is suitable for testing with paper strips.

The research, published in the peer-reviewed Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal, not only facilitates rapid cyanide detection but also paves the way for advanced sensor-based smart devices using digital logic circuits.

The sensor changes colour and emits bright fluorescence in the presence of cyanide, contributing to both environmental safety and forensic investigations.

Cyanide is a highly toxic compound that is widely used in industrial processes such as manufacturing of synthetic fibres, metal cleaning, plastics, electroplating, and gold mining, according to G Krishnamoorthy, a professor at the chemistry department of Indian Institute of Technology (IIT), Guwahati.

"Improper disposal of cyanide often leads to its release into the environment, contaminating soil and water sources. Consumption of this contaminated water can disrupt oxygen supply in human body. Even a small amount can cause severe health effects or death. Therefore, there is a need to develop sensors that can detect even trace amounts of cyanide in various materials," he said.

Fluorescent chemosensors are chemicals that light up under light when they interact with specific chemicals. These sensors are popular due to their ease of use, low cost, high sensitivity and potential for use in biological systems. While many existing sensors work by dimming their light (known as a "turn-off" response) when detecting substances, a "turn-on" response -- where the signal brightens instead -- is often more effective because it avoids false negatives and improves detection clarity, he added.

The IIT, Guwahati, team has developed a "turn-on" chemosensor that emits a weak blue fluorescence under ultraviolet light. In the presence of cyanide, this fluorescence turns on and shifts to a brighter cyan colour due to a chemical change in the molecule.

"This reaction is highly specific to cyanide, especially in a carefully selected solvent system that includes water. What sets this sensor apart is its versatility. The sensor works not only in lab solutions but also in river and tapwater samples, with an accuracy of 75-93 per cent.

"It can be embedded into paper strips for portable testing and is effective in live cell imaging. In fact, the sensor was used to detect cyanide inside biological cells, showing promise for applications in environmental and forensic investigations," Krishnamoorthy said.

The research team conducted a combination of lab experiments and advanced computational calculations called Density Functional Theory (DFT) to confirm the sensing mechanism of the developed technology.

The researchers also demonstrated that this molecular sensor could function like a basic logic gate, a key element in digital electronics. This means it may have future use in developing smart, sensor-based electronic devices that can detect harmful chemicals like cyanide in real time.

"As the next step, the research group is working on developing a simple kit for testing a variety of analytes. This development opens new possibilities for easy, rapid, and reliable cyanide detection in environmental, medical, and industrial settings using a cost-effective tool and basic ultraviolet light -- making it accessible for wide use," said Bithiah Grace Jaganathan, a professor at the Department of Bioscience and Bioengineering.

The team also inlcuded research scholars Mongoli Brahma, Arup Das Kanungo, Minati Das and Sam P Mathew. PTI GJS GJS SZM SZM