Costs one-twentieth of imported carbon quantum dots (CQDs).

A team of scientists in Assam has developed a chemical process that turns ‘dirty’ coal into a biomedical ‘dot’ to help detect cancer cells.

The team, led by Binoy Kumar Saikia and Tonkeswar Das, has applied for a patent for their chemical method of producing carbon quantum dots (CQDs) from cheap, abundant, low-quality and high-sulphur coals.

CQDs are carbon-based nanomaterials whose size is less than 10 nm, or nanometre.

“Carbon-based nanomaterials are used as diagnostic tools for bio-imaging, especially in detecting cancer cells, for chemical sensing and in opto-electronics. A few chemical companies in the U.S. and Japan have been manufacturing CQDs. What we have done is develop fluorescent carbon nanomaterials at one-twentieth the cost of imported CQDs,” Mr. Saikia told The Hindu on Wednesday.

He is a scientist in the Polymer Petroleum and Coal Chemistry Group of the Council of Scientific & Industrial Research-North East Institute of Science and Technology (CSIR-NEIST) in eastern Assam’s Jorhat, about 300 km from Guwahati.

The CQDs that the CSIR-NEIST team developed emit a bluish colour with “high-stability, good-conductivity, low-toxicity, environmental friendliness, and good optical properties”. The finer details have been published in their study published in the Journal of Photochemistry and Photobiology.

“Our source material is abundant, low-quality Indian coal not directly suitable for thermal electricity production. Even if the selling price is twice our cost of production of ₹50 per ml, it will be much cheaper than the imported CQDs with market price of up to ₹2,000 per ml,” he said.

Scientists said CQDs are futuristic materials whose demand in India has been increasing leading to a considerable volume of import. The CSIR-NEIST technology can produce approximately 1 litre of CQDs per day at a low cost to become an import substitute.

Other advantages of the process are the use of environment-friendly reagents and less water than methods elsewhere. The process can also be recycled with a manageable supply chain, the scientists said.

The other members of the team that developed the “blue fluorescent and biocompatible carbon dots derived from abundant low-quality coals” are H.P. Dekaboruah, Manobjyoti Bordoloi, Dipankar Neog, Jayanta J.Bora, Jiumoni Lahkar, Bardwi Narzary, Sonali Roy, and Danaboyina Ramaiah.