New Delhi, Sep 1 : Researchers at the Indian Institute of Technology Guwahati have developed a novel sensor from milk protein and thymine that can detect mercury and antibiotic contamination in water, which can lead to cancer.

With rapid urbanisation, industrial activities, and overuse of pharmaceuticals, water contamination is becoming a pressing issue, putting ecosystems and human health at risk worldwide.

The team built the nanosensor from extremely small materials that are a few billionths of a metre in size.

The sensor uses carbon dots that glow under ultraviolet light. In the presence of harmful substances such as mercury or tetracyclines, the glow of these carbon dots dims, providing a quick and visible signal of contamination, even at low concentrations.

'Detection of pollutants such as mercury and antibiotics is important, not only in water but also in biological fluids. Mercury is highly carcinogenic. Excess antibiotics also pose adverse health consequences. This sensor can detect mercury and tetracyclines at a very low concentration,' said Prof. Lal Mohan Kundu, Professor, Department of Chemistry, IIT Guwahati.

Tetracyclines are a class of antibiotics commonly used for pneumonia and respiratory infections. If it is not disposed of properly, it can easily enter the environment, contaminating the water, which can result in antibiotic resistance and other health hazards.

Similarly, mercury, in its organic form, can cause cancer, neurological disorders, cardiovascular disease, and other life-threatening conditions. Detecting these pollutants accurately and quickly is essential to protect both water quality and public health.

For the project, published in the journal Microchimica Acta, the team synthesised the carbon dots from low-cost and biogenic precursor milk protein and thymine -- a nucleobase.

The new sensor can also be used in 'biological systems', said Kundu, adding that carbon dots were chosen 'because of their nanoscale dimensions and inherent fluorescence property. This makes it a highly sensitive technique.'

On a laboratory scale, the developed sensor demonstrated accurate results with a measurable dimming of its glow within less than 10 seconds of meeting harmful contaminants.

The sensor is extremely sensitive in mercury detection with just 5.3 nanomolar (1.7 parts per billion), which is below the safety standards set by the US Environmental Protection Agency, and 10 -13 nanomolar for Tetracycline antibiotics.

To ensure its versatile utility, the researchers also tested the sensor in a variety of environments, such as tap and river water, milk, urine, and serum samples.

Further, to enable quick and on-the-spot testing, the research team coated the developed sensor in simple paper strips, which can easily detect water contamination using an ultraviolet lamp.

The novel sensor not only provides a low-cost and highly accurate alternative to conventional water testing, but its biocompatibility also holds the potential for broader biomedical applications in the future, the team said, while also calling for further validation before rolling out for commercial application.

/IANS