Why in news?

• Scientists at the Raman Research Institute (RRI), Bengaluru, have developed a breakthrough technique to detect toxic molecules like Rhodamine B at extremely low concentrations using the "coffee-stain effect."
• The RRI technique uses Surface-Enhanced Raman Spectroscopy (SERS) amplified by the natural coffee-stain pattern of dried droplets containing gold nanorods.

About the RRI Rhodamine-B Detection Research

• Rhodamine B is a banned synthetic dye in food due to its toxic effects on skin, eyes, respiratory system, and its environmental persistence.
• Monitoring illegal use of Rhodamine B is difficult as it often occurs in very low concentrations undetectable by standard techniques.
• The RRI technique uses Surface-Enhanced Raman Spectroscopy (SERS) amplified by the natural coffee-stain pattern of dried droplets containing gold nanorods.
• Gold nanorods aggregate in a ring pattern during evaporation, creating hotspots that amplify the Raman signal, enabling detection of extremely low dye levels (down to 1 part per trillion).
• The technique is simple, cost-effective, and potentially applicable with portable devices for field testing.
• Beyond Rhodamine B, this approach could detect other contaminants in food, water, and the environment, aiding regulatory and public health efforts.

Health and Environmental Relevance of Rhodamine B

• Causes DNA damage and mutations, linked to cancerous growths in animal studies.
• Can provoke allergic reactions and skin pigmentation changes on prolonged exposure.
• Persistent environmental pollutant, challenging to detect in natural water bodies.

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