A team of scientists from the Institute of Nano Science and Technology (INST), an autonomous institute under the Department of Science and Technology (DST), has developed a tiny fluorescent “turn-on” sensor capable of rapidly detecting nicotine and its primary metabolite cotinine in aqueous solutions and living cells.
The innovation could enable early and efficient detection of nicotine exposure by tracking cotinine, a stable biomarker found in blood, saliva, and urine that reflects long-term nicotine presence in the body. This breakthrough holds significant potential for public health monitoring, smoking exposure assessment, and biomedical research.
Smoking and second-hand smoke exposure continue to be major global health concerns. While nicotine is highly addictive and harmful, cotinine serves as a reliable indicator of tobacco exposure. However, conventional detection methods such as GC-MS, HPLC, electrophoresis, and immunoassays are often costly, time-consuming, and require complex laboratory procedures.
To address these challenges, the researchers developed a sensor based on iron metal-organic framework (Fe-MOF) nanospheres—porous, sponge-like nanostructures composed of iron. These nanospheres were synthesized using a solvothermal process and tested for safety and effectiveness.
The porous structure allows nicotine and cotinine molecules to enter and interact with the material, triggering a fluorescence “turn-on” response that becomes brighter and shifts toward blue light. The sensor was found to be highly selective, recyclable, and easy to use in aqueous environments.
Using advanced imaging techniques such as confocal microscopy, the team observed cellular uptake of the nanospheres and confirmed their sensing behaviour inside living cells. The fluorescence enhancement is attributed to host–guest interactions and electron transfer within the material.
Published in the journal Nanoscale, the study highlights that iron-based MOFs offer advantages such as low toxicity, high biocompatibility, and suitability for biological applications. This makes them promising for non-invasive health monitoring and development of low-cost diagnostic tools.
The innovation could pave the way for rapid screening of tobacco exposure and expand fluorescent MOF-based biosensing platforms for detecting other disease-related biomarkers in the future.
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