Researchers at the Indian Institute of Technology Guwahati (IIT Guwahati) have developed a novel nanosensor using milk protein and thymine that can rapidly detect mercury and tetracycline antibiotics contamination in water. The research was led by Prof. Lal Mohan Kundu, Department of Chemistry, along with research scholars Ms. Pallabi Paul and Ms. Anushka Chakraborty.
The sensor employs carbon dots that glow under ultraviolet (UV) light. When exposed to harmful substances such as mercury or tetracyclines, the glow diminishes, providing a quick and visible signal of contamination.
Growing Threat of Water Pollution
With rapid urbanisation, industrial activities, and the overuse of pharmaceuticals, water contamination has become a pressing global issue, threatening ecosystems and human health.
- Tetracyclines, widely used to treat pneumonia and respiratory infections, often enter the environment through improper disposal. Their presence in water contributes to antibiotic resistance and other health risks.
- Mercury, especially in organic form, poses severe dangers such as cancer, neurological disorders, cardiovascular disease, and other life-threatening conditions.
Detecting these pollutants quickly and accurately is critical to protecting water quality and public health.
How the Nanosensor Works
To tackle this challenge, the IIT Guwahati team created a nanoscale sensor, made of materials just a few billionths of a meter in size. These carbon dots, derived from low-cost biogenic precursors—milk protein and thymine, emit a natural fluorescence under UV light.
In the presence of mercury or tetracyclines, the fluorescence dims within less than 10 seconds, offering a fast, sensitive, and highly visible detection method.
Prof. Kundu explained:
“Detection of pollutants such as mercury and antibiotics is vital, not only in water but also in biological fluids. Mercury is highly carcinogenic, while excess antibiotics have severe health consequences. This sensor can detect these contaminants at very low concentrations. Its nanoscale dimensions and inherent fluorescence make it an extremely sensitive technique.”
Sensitivity and Versatility
On a laboratory scale, the nanosensor has demonstrated exceptional sensitivity:
- Mercury detection at just 5.3 nanomolar (1.7 parts per billion), which is lower than the safety standards set by the U.S. Environmental Protection Agency.
- Tetracycline detection between 10–13 nanomolar, ensuring precise monitoring.
To test versatility, researchers applied the sensor in various environments, including tap water, river water, milk, urine, and serum samples. For field-friendly applications, the team coated the sensor on simple paper strips, allowing quick contamination detection with the help of a UV lamp.
Broader Impact and Future Applications
As per IIT Guhawati Press release, the findings of this study, published in the journal Microchimica Acta, highlight the sensor’s potential beyond conventional water testing. Its low cost, high sensitivity, and biocompatibility make it suitable for broader biomedical applications, offering a promising tool for protecting both environmental and human health.