Institute of Advanced Study in Science and Technology (IASST), Guwahati, has developed an electrochemical sensing platform for detecting carcinogenic or mutagenic compounds N-nitrosodimethylamine (NDMA) and N-nitrosodiethanolamine (NDEA).

NDMA and NDEA are sometimes found in food items like cured meat, bacon, some cheeses, and low-fat milk.

It was achieved by developing a modified electrode by immobilising carbon nanomaterials (carbon dots) in DNA.

IASST scientists pointed out that with changing food habits of urban Indians, they are exposed to harmful chemicals belonging to the nitrosamine family in cured meats, bacon, some cheese, low-fat dry milk, and fish.

Such chemicals include carcinogenic ones like NDMA and NDEA, which may also alter the chemical composition of our DNA.

Hence, it is important to develop detection techniques to detect them.

Most of the techniques used for the detection of Nitrosamine have detection limits in ?M.

In this study, published in the journal ACS Appl. Bio Mater, IASST scientists have fabricated an electrochemical biosensor using DNA immobilised on the surface of carbon dots for sensitive and selective detection of N-nitrosamine.

The detection limit was determined to be 9.9×10?9 M and 9.6×10?9 M for NDMA and NDEA, respectively.

The electrochemical biosensor platform was developed using the ability of NDMA and NDEA to alter the DNA.

Carbon dots (CDs), a carbon-based nanomaterial, were used, which is already established as a biocompatible and environmentally friendly material.

Naturally derived chitosan (a natural biopolymer obtained from the shells of shrimp, lobster, and crabs) is an environmentally friendly, sustainable material that was used to synthesise CDs.

As this is an electrochemical sensor, the electrode was developed by depositing carbon dots (carbon nanoparticles) and then immobilising bacterial DNA on them.

This electrode system was used to measure the current peak.

Both NDMA and NDEA alter the chemical structure of DNA present in the electrode, making it more conductive, which ultimately results in the increased current peak.

The IASST scientists took advantage of the fact that out of the base pairs A, T, G, C, Guanine (G) is electrochemically active.

In the presence of NDMA, guanine is modified to 6-Omethylguanine or 7-methylguanine and with NDEA, guanine changes to 8-oxoguanine to form DNA adducts.

The DNA adducts formed are electrochemically active, which ultimately leads to an increase in peak current in the electrochemical setup, helping in the detection of the chemicals.

Some other structurally similar chemical compounds were also added to check if they can interfere with the system.

But as these chemicals cannot alter the DNA sequence, they do not affect the system.