In a breakthrough for water safety and public health, researchers at the Indian Institute of Technology (IIT) Guwahati have developed a nanosensor made from milk protein that can instantly detect cancer-linked mercury and harmful tetracycline antibiotics in water and biological samples.

The pioneering work, led by Prof. Lal Mohan Kundu from the Department of Chemistry along with his scholars Pallabi Paul and Anushka Chakraborty, employs thymine-based carbon dots that glow under ultraviolet light. When exposed to mercury or antibiotic traces, the glow dims—signalling contamination within seconds.

Rapid urbanisation, unchecked industrialisation, and pharmaceutical misuse are accelerating toxic water contamination across the world. Mercury, even in minuscule amounts, can trigger cancer, neurological damage, and heart disease, while excessive tetracyclines in the environment not only pose health risks but also fuel antibiotic resistance.

How it works

On a nanoscale, the sensor detects pollutants in under 10 seconds—identifying mercury at 5.3 nanomolar (1.7 ppb) and tetracyclines at 10–13 nanomolar, levels well below U.S. Environmental Protection Agency safety thresholds. Researchers have successfully tested it in tap water, river water, milk, urine, and serum samples, proving its wide applicability.

To make detection accessible, the team also coated the nanosensor onto simple paper strips that can be used on-site with a basic ultraviolet lamp—an affordable solution that could revolutionise water quality monitoring.

“The sensor is highly sensitive, biocompatible, and low-cost. Its use can go beyond water safety to biomedical systems,” said Prof. Kundu, underlining the potential of the technology.

The findings, published in the journal Microchimica Acta, position this innovation as a powerful tool in safeguarding public health while tackling rising threats from environmental pollutants and drug resistance.