Scientists find way to use teak leaves to protect human eyes from radiation | Bengaluru News

Bengaluru: Scientists from the city’s Raman Research Institute (RRI) have discovered that an extract from teak (Tectona grandis) leaves can act as a natural, biodegradable shield against high-power laser radiation. This development could lead to safer, greener alternatives for protecting delicate optical devices and human eyes in medical, military, and industrial settings.Teak leaves, often discarded as agricultural waste, are rich in anthocyanins, natural pigments responsible for their reddish-brown colour, the department of science and technology (DST) said.The current work, researchers say, not only adds value to agricultural waste but also supports the development of sustainable photonic materials. Researchers say that further studies could improve the dye’s stability and extend its use in commercial photonic devices. Potential applications include laser-resistant coatings, safety goggles, and sensor shields, contributing to the growing demand for green optical tech.Researchers at RRI found that when extracted, these pigments exhibit non-linear optical (NLO) properties, particularly reverse saturable absorption (RSA), where the material absorbs more light as the intensity increases. This makes the dye ideal for laser safety applications.“Teak leaves are a rich source of natural pigments, such as anthocyanin, which imparts a characteristic reddish-brown colour when extracted using suitable solvents,” said Beryl C, DST woman scientist at the light and matter physics theme at RRI. “We aimed to explore the potential of teak leaf extract as a non-toxic, biodegradable, eco-friendly, and economically viable alternative to synthetic dyes in the field of non-linear optics,” Beryl added.To prepare the dye, the team dried and powdered teak leaves, soaked the powder in solvents, and purified the extract using ultrasonication and centrifugation. The final product was a reddish-brown liquid tested using green laser light at both continuous and pulsed intensities. The extract adapted to the light and absorbed it more intensely at higher power levels.Using specialised methods, researchers confirmed the extract’s RSA behaviour. These results suggest that the teak-based dye could be used in optical limiters — devices that protect sensors and eyes from sudden laser bursts.“The study, published in the Journal of Photochemistry and Photobiology A: Chemistry, highlights the extract’s potential to replace synthetic materials such as graphene, fullerenes, and metal nanoparticles, which are expensive and environmentally harmful due to their complex manufacturing processes,” DST said.